Construction - Standing Seam Steel Roof - Part I: Shopping, Ordering and Receiving

Two and a half years ago, I posted on two design options for steel roofing that we needed to consider, viz., standing seam with concealed fasteners and the exposed fastener type that is used for siding more often than for roofing.  The former is less likely to leak because the standing seam diverts runoff from the junction between panels and almost all of the fasteners are located and protected under the seam where leakage around them becomes moot.  The exposed fastener panels have two drawbacks.  All of the screws remain uncovered and are subject to leakage if the hex-head screws are not tightened precisely for a good seal of the elastomeric washers under their heads.  Also, the seams are relatively flat lap joints that do not divert water to the degree that standing seams do.

At the time of that posting, I was leaning towards the cheaper exposed fastener option in order to stay on budget.  Since then, reality has set in; the budget has become so distorted (grist for a future post after construction is completed) that, when it came time to order the roofing, the additional cost of the concealed fastener design was easy to justify.  Also, the roof pitches turned out to be lower than I imagined at the time of the posting to the extent that the exposed fastener design would have been too much of a gamble.


But First, Why a Steel Roof At All?
Because it is more sustainable.  It contains recycled steel initially and it can be recycled again at its end-life, unlike petroleum-based shingles that end up land-filled.  The life expectancy of a steel roof is several times that of even the most expensive asphalt shingles.  And the steel panels resist hail damage better than shingles and can be purchased in highly reflective colors to reduce solar gain for a cooler roof.  White panels, for example, are 100% reflective; the light gray that we are using is almost as reflective (upon request, Menards corporate provides information on the reflectivity of its steel roofing colors that may not be available at the store level).  The energy embodied in raw materials, manufacturing and transportation to the end-user must also be included in any assessment of sustainability.  Shingles and steel panels both require extractive sourcing but the former is a one-use product while the latter is recyclable.  A comparison of the energy embodied in their manufacture is beyond my pay grade but I suspect the recycled content of steel may tip the scales.  Energy embodied in transportation to the end-user is a case-by-case scenario.  Our steel panels from Menards came from a plant near Omaha, NE that is +/- 375 miles away which is well within the LEED standard of 500 miles maximum for the transfer of materials to the building site.  

Should a Steel Roof Be DIYed?
In my experience, the learning curve for steel roof installation is flatter the than for some other phases of home-building such as plumbing the waste system or cutting stair risers and certainly less challenging than drywalling cathedral ceilings.  Perhaps the most difficult task is cutting panels that cannot be pre-cut by the fdactory.  As I will describe in a subsequent post, even that is manageable.  Having said all of that, I must admit that, for someone my age, hanging out on roofs is a little more iffy now than it used to be. Otherwise, a steel roof is easily within the scope of a DIYer home-builder.

Placing the Order 

Crates of roofing haphazardly strewn about by Menards'
crude delivery protocol 

I compared the price, quality and color selection of several manufacturers of steel roofing and decided to buy ProSnap Steel Roofing from Menards.  Apparently, one of its subsidiaries fabricates steel cladding products which makes their purchase relatively hassle-free for consumers and DIYers.  Indeed, I found the latter to be true except for their delivery equipment that was so awkward and inefficient that the outsize containers were dropped haphazardly at the building site.  Thank goodness I had forks

The damage to the long crate at the rear in the picture
above by the time it was moved to the garage;
 fortunately only one panel was unusable

for my trackloader with which to gather them up and move them to storage in the newly-built garage.

All that is required for a quote and to place an order are reasonably accurate scaled drawings of the roof(s) and a color selection.  I found out the hard way that not all drawings are treated with the same degree of thoroughness by Menards.  When achitectual drawings are submitted in parallel with the scaled DIY drawings, the steel plant emails digital drawings to the customer for approval and a signature.  However, with only DIY drawings, there is no digital feedback from the factory -- the order is shipped without any further communication.  

The accuracy of the factory drawings is best documented by remeasuring the roof with the factory drawings in hand before signing off on them.  Special attention should be given to panel lengths for intersecting slopes on either side of a valley.  And there are a myriad components other than the panels themselves that must be vetted such as flashings of several types, roof edge protectors, vented and unvented ridge caps, and several different fasteners, moisture blockers and mastics. 

Our color selections for roofing and siding were based on reflectivity, i.e., the ability to reflect the sun's rays, in order to maximize the efficiency of wall and ceiling insulation in summer.  Accordingly, we chose highly reflective light gray for the roof and bright white for the siding instead of less reflective, but perhaps more interesting, darker colors.

Staging the Components
The first step in the installation process is to unpack the delivery crates and organize the contents so as to verify that all the components have been received in good condition and to get a leg up on finding them as needed during installation. The latter was particularly important in our situation because three roofs of different sizes were involved, one of which was a hip roof for which the panels varied in length.  Also, as a DIYer, it was important to familiarize myself with the ancillary components that were specified by the factory as add-ons after the order was placed.

In our case, there were two glitzes, one minor and one extremely major. 

The minor one was a panel having localized damage -- denting and abrasion of a small area --  that rendered it unusable but for which Menards readily issued credit.  The bigger problem stemmed from the fact that the measurement I gave Menards for the length of the panels for the garage roof was 10" too short due to a transposition.  The steel for the garage roof had been a last-minute add-on to the original order and, after reviewing the paperwork, I realized that I had not received a digital drawing of the garage roof from the manufacturing plant for dimension verification and a signature before the order was processed.  In the absence of architectural drawings, the cost of the mistake was entirely on me as far as Menards was concerned at a cost of about $1,000.  The reality message here is that a DIY home builder accumulates a lot of knowledge and skills, sometimes the hard way, that have limited or no future value, especially for someone my age.  But that doesn't diminish the joy of the onetime  journey.

The next post covers the installation of the roofing.

Construction - Porch , Solar Overhang, Soffets and More

My blog posts over the past several months have had more to do with dirt work than with carpentry.  While there is still some dirt work to do, mainly installation of the insulation/watershed umbrella west of the house, it is good to get in some carpentry for a change.

Framing for the Screened Porch
Glen, a journeyman carpenter friend, and I took advantage of some warm and dry weather in January to do most of the framing for the porch

Framing for the hip-roofed screen porch

but we were not able to carry it to the sheathing stage until mid-summer because of rainy spring weather and the fact that I needed time off from carpentry to finish the dirt work that I described in recent posts. The hip roof for the porch was well beyond my expertise so it made sense to stand aside and let Glen lead rather than learning its complicated construction for a one-time situation.  In order to save money and to be able to design as we worked, we stick-built it in lieu of trusses.  The framing included ceilings for both the porch and the walk overhang to make them cooler and have a more finished look.

Covered Walkway
We framed and sheathed a roof for the walkway that runs between the porch and the front door of the house.  Since it even extends slightly over the nearest garage door, we will be able to navigate undercover from the kitchen/porch door to the front entry or garage door.  The walk overhang is a continuation of, and blends in with,

This photo shows partial framing and sheathing of the
overhang for the second story clerestory windows as well
as the covering for the walkway between the screened
porch and the front entry; also visible is the beginnings
 of the temporary second story scaffolding against the
south wall

the porch roof.  It is carried by a double 2 x 12 beam running from the porch to the house without intervening post support.  Since the overhang is wider than the walk, a post would have required unwanted penetrations through the insulation/watershed umbrella (the installation of which was covered in a prior post).

Clerestory Window Overhang
All that is needed to keep unwanted midsummer sunshine off of the second story clerestory windows an dedicated overhang extending about two feet outward from the house just above the top trim for the windows.  Here pre-made trusses did make sense for saving time and money.  Closed cornices at each end of the overhang handle the transitions between the facia of the steeply sloped overhang and the facia of the low-slope second story roof.  The one at the west end could be built from a ladder standing on the first story roof but the one on the east was 25 ft above the ground and its complexity would require an impossible number of trips up and down a ladder. 

Po Man's "Cherry Picker"

Second stage scaffold

Construction of the east end of the overhang was a perfect example of the extraordinary measures one uses when working alone with a tight budget.  A contractor would probably have called in cherry-picker-like equipment for the job or set up steel scaffolding whereas I knew that working alone would take sufficient time to make rental fees for either approach off budget.  I constructed instead a substantial temporary scaffold from which to work safely.

The scaffold, that was anchored to the floor and ceiling inside the house and cantilevered through the wall, was done in two stages.  The first was adjacent to the south-facing wall for the purpose of framing, sheathing and roofing

Anchoring design for the cantilevered scaffold

the overhang as well as installing the facia and soffet.  The second stage was added later at a right angle to the first and wrapped around the corner of the house for the sole purpose of building and painting the closed cornice at the junction of the overhang roof and the second story rake roof and the associated soffets. The second scaffold, though, was in the way of installing the garage roof so it gave way to a successor that I will describe in a future post.  The south scaffold stayed in place until the metal roof and the soffet for the overhang were completed but will be in the way and have to be removed before installing the first story metal roof, the clerestory windows and the second story metal siding.

Soffet / Cornice Construction
The framing for the underside of any roof overhang comprises either rafter tails on the eave side or their equivalent called lookouts, on the rake side.  The tails and lookouts can be left exposed for a rustic look or can be veneered on the

Wedges added to the rafter tails (green);
notice the use of the Rainhandler instead
of a conventional gutter

bottom with a soffet, which means that, on the rake side, the soffet follows the slope of the roofin one direction and is horizontal in the other while, on the eave side, the soffet simply follows the slope of the roof.  The transition of the facia at the corner between the eave and the rake is uncomplicated whether there is a soffet or not.

However, the eave side is often modified to give a more finished look by making the soffet horizontal with special framing or by using
proprietary soffet materials like vinyl or metal to effect horizontal-ness without the benefit of framing.  But doing so creates an awkward transition of the facia and the soffet at the corner between the eave and rake that has to be reconciled by what is called a cornice return.

Our design called for a horizontal soffets and cornice returns for all overhangs.  Since the pitch for all of our roofs is low, it was easier to add 2-by wedges, to the bottom of the rafter tails than to frame horizontally or use proprietary materials.  The cornice returns were relatively simple except for the abrupt change from the second story overhang and the low-pitch second story roof.

Using a jig on the table saw for cutting the wedges

Steel Soffets
Modern soffets are usually not framed in.  Instead they are created with short pieces of vented vinyl or aluminum, and occasionally steel, running perpendicular to the wall of the house.  I opted for steel soffet material that can be purchased in convenient 12' lengths that run parallel to the wall.  The way I used them was to frame (as in picture frame, not structural frame) the periphery of the soffet with salvaged 1x lumber that I rabbeted underneath to accept and hide the edges of the vented steel panels.  Once the panels were tucked under the frame, I screwed them to the bottom of the wedge-added rafters and the rafter tails.

Metal Roofing and Siding At Last!
The roof sheathing has been protected by either 6 mil plastic sheeting or 30 lb felt paper, or both, for many months while awaiting the day the steel roofing could be installed (prior post on temporary protection).  Finally, the completion of the porch and the overhangs made it possible to measure and order both the roofing and the steel siding.  (For a discussion of and the rationale for standing seam steel roofing, go to the post on roof design and for steel siding, go to the post on wall cladding.)

All that was needed for estimates on roofing and siding was to produce homemade scaled drawings that provided the information the manufacturer needed for both the steel panels and associated steel trim pieces. The manufacturer countered with two things:  (a) a list of components for careful vetting and (b) digital drawings that could be taken back to the building for dimension verification before finalizing the order.  In order to reduce the cooling load, we ordered roofing and siding with color shades that had a high solar reflectance -- light gray for the roof and white for the siding.

The next task is to get the garage undercover in order to have dry storage for the steel cladding.

Odds 'N Ends - Experience with Bare-Rooted Tree Seedlings

The economical way to have shrubs and trees in quantity is to start with bare-rooted seedlings that we here in the Midwest can order from our state conservation departments for less than a dollar each.  However, seedlings require a lot of TLC until they become established during the first growing season.  For what it's worth, I would like to share our experience with them on two occasions.

Reminder:  click on any photo to enlarge it for better viewing.

Current Project
Last fall, we placed an order with the state conservation

department for 80 bare-rooted seedlings to be delivered in the first week of April.  I thought that we would be finished with the dirt work behind the house by early spring and could start a woods behind the house using species of hardwood trees that are recommended by Doug Tallamy in his quintessential book on native landscaping as being the  most beneficial to wildlife.  "Wildlife" not only means the kind with four legs or two wings but also, and perhaps more importantly, a host of insects like pollinators that depend on trees for part of their life cycles.

By the time I finished the final grading behind the house, the exposed soil in many areas was hardpan (glacial till) through which tree roots do not penetrate and the thin layer of topsoil that I deposited would support at best only shallow-rooted nuisance grasses like crabgrass. The bare-rooted seedings would have to be planted somewhere else.  Fortunately, the acre lot on which we live next door to the construction site combined with that part of the building site that could support trees would provide ample spacing for the seedlings.

Temporary "Planting"
The delay between arrival and planting of the seedlings required that they be temporarily "planted" to keep the roots happy.   Dorothy and a friend dug shallow trenches in Dottie's fenced garden, laid the plants on the ground with their roots in the trenches and covered the roots with a shallow layer of soil, a maneuver called "heeling in".  After watering the protective soil, they covered it with cardboard and old carpet to hold in the moisture.  Then as needed, Dottie kept the plants watered until ready for planting.  However, holding them in this fashion for two months does not bode well for success; more of the seedlings did not survive than would have been the case if they had gone into the ground either when received or shortly after.  Mostly it was nearly ten of the black oaks that suffered due to spindly root structure compared to the other varieties -- white oak, burr oak, shumac oak, pin oak, hackberry and black cherry.

 Planting the Seedlings
Nothing needs to be said about digging a hole big enough for root cluster and refilling it while holding plant in the correct position to have the root-trunk junction at the right level.  I would mention, though, that for easy digging, I used a clam-type posthole digger then, for the tree seedlings having tap roots, such as the oaks and black cherry, I used a soil auger in a cordless drill to deepen the center part of the hole.  I made no attempt to amend the soil beyond using only topsoil for backfilling.

Ideally, the trees should be planted randomly so as to mimic a natural forest.  But, in order to make mowing with a lawn tractor easier, I held my nose and planted them in a grid pattern, allowing about 20' between trees.

Protecting the Seedlings from Critters
The topography here in the Mississippi River bluffs is sufficiently rough to provide numerous timbered gullies that are rugged enough to stay undeveloped.  As a result, our town supports a lot of closeup and personal wildlife.  A friend gave us some oak seedlings last summer that we planted without protecting immediately.  Within a day or two they had been eaten, probably by deer but maybe rabbits.  This time we didn't let the the seedlings go unprotected even for one night.

A quick Google search reveals myriad choices for cylinders in which to grow trees until they become established, usually called "grow tubes".  They range from solid plastic tubes with various hues to tubes that are like stiff netting.  Most are supported by small diameter bamboo sticks that are pushed into the soil.  We chose the netting type seedling protection tubes that are used with reforesting after clear-cuts in northwest USA because they are much cheaper than the "mini-greenhouses" that the solid variety comprise.  Mating the netting with the bamboo stick was a simple matter of of weaving the bamboo through the netting in a few places.

Initially, we used mulch around the seedlings to hold moisture and to keep grass at bay.  In order to do the latter effectively, though, the mulch area would have to be substantial.  Instead, we opted for a small amount of mulch initially to cover the soil that was denuded during planting with the intention of letting the grass grow up to the seedling eventually -- kinda.

Protecting the Seedlings from Mowing
If grass encroaches on the seedling, how do you mow it? 

4" PVC pipe +/-8" long cut
 partway through on one
side and completely through
 on the other

 Before placing the grow tube over a seedling, we slipped a 8" section of 4" PVC pipe that had been modified for easy removal (next paragraph) when the tree trunk got too big for the pipe.  Then we slipped the grow tube part-way over the pipe then forced the bamboo into the ground.  The bamboo supports both the pipe and the grow tube.

In order to facilitate removal of the pipes, they were run through the table saw twice.  For the cut on one side, the blade was adjusted so as to cut only about two thirds of the way through the wall thickness.  The second cut on the other side went completely through the wall of the pipe.  At the time of removal, it will be a simple matter of using a flat tool to pry the cut side of the pipe apart until the partially-cut side breaks apart.

In the meantime, I will be able to string-trim the grass

A drip hole of 1/16" drains the
2.5 gal container in +/-2 hours

up to the pipe without damaging the grow tube or the seeding.  Eventually, after removal of the tubes and pipes, mulching out a ways from the trees in a more typical manner will be necessary until the trees grow into a proper woodland whereby the shade, leaf litter and forest-specific undergrowth will eliminate mowing. 

Drip Irrigation During the First Season
The closest thing we have had to a genuine drought was in 2012, the year we raised about 60 bare-rooted seedlings in anticipation of having them reach a transplantable age by the time we needed them for landscaping around the new house.  Lo, six years later when we are finally at the landscaping stage, the seedlings were way past transplanting.  However, despite the drought that year, all but a handful of seedlings survived thanks to the drip irrigation system that was suggested by the farmer in our family who also provided the containers for it.  And, in retrospect, our success was also due to growing them only a few feet apart in an enclosure
that kept the deer at bay for a couple of years until large enough for the deer to reach them over the fence.  By that time though, a little pruning did not matter.

Any decent-sized container -- round, square, rectangular -- can be modified for drip irrigation.  The 2 1/2 gallon containers we obtained from brother-in-law, Ron, originally held a surfectant that is used to enhance the effectiveness of sprayed weed killers.  Thorough rinsing with tap water is all that is needed to make them safe for watering plants.  By trial and error, I found that a 1/16" diameter drip hole as close to the bottom as possible will mean that the container will drain in about two hours.  Rather than hassling with the lids for the containers at each fill-up, we left them off.  Some debris does find its way through the opening, mostly grass clippings from mowing nearby, but it is largely flushed out by overfilling the container with water each time.

As ballast against the wind, I add enough pea

Pea gravel after washing; a quart in each container is
ballast enough against most winds and keeps mosquitoes
 from breeding in any water standing after draining 

gravel to each container to cover the bottom -- about a quart for our containers.  In addition to keeping the containers anchored, the gravel covers any water still standing after the drip stops, making it inaccessible to mosquitoes.  And, being a bit anal, I try to position the containers on the north side of the seedling so as not to block the sun.

While filling a container with water, it is a good idea visually to check the drip hole to be sure it is flowing freely.  I carry a 4d finish nail for reaming any sluggish holes.  Also, during dry spells, I jump-start the watering by filling the PVC pipes with water either before or after filling the containers.  It slowly leaks out through the sawcut but the soil around the plant is nevertheless thoroughly saturated.

At the end of the growing season, it is advisable to be sure the containers are dry and stored where they cannot collect water that could freeze and burst a container.  When reusing the containers, it is best from the standpoint of preventing clogged

drip holes to empty the gravel into a wash tub or some other large vessel filled with water.  Then, stir the gravel until vegetative debris floats to the surface and goes away when the water is poured off.  Rinse the containers clean, add back the gravel, prophylacticly ream the drip holes and

start watering.

Seedlings planted between new house and our residence

The nearby photo shows the configuration of the protective PVC pipe, the protective grow tube with a bamboo support stick and the drip irrigation container.  Notice that the container is tilted away from the plant, which is not always avoidable, meaning that the container will not drain entirely. The layer of pea gravel in the bottom covers any standing water sufficiently that mosquitoes cannot breed in it.  The black cherry seedling is already growing through the tube netting but, our experience is that deer browse will not harm the tree at this early stage as long as there is plenty of growth within the tube.  

A garden hose works best for filling the containers either directly from a silcock or indirectly from a mobile tank.  Since most of our seedlings cannot be reached with a hose from the house, we temporarily re-purposed our rain barrel for this job. It has a hose bib at the bottom for a garden hose and a hole on top for filling.  When lashed to my truck bed, there is enough gravity flow to fill a container in just a few minutes.

Seedlings on our residence property; beginning in August, apple-loving
deer are regular visitors at dusk and through the night eating directly
off of the trees in the background and picking up fallen apples

*  *  *  *  *       
Update
Several of the grow tubes and PVC pipes have been "vandalized with the bamboo poles broken off at the ground and the netting and PVC pipes strewn across the lawn as well as few leaves left on the seedlings.  About a dozen seedlings were bothered.  Our vintage apple trees are magnets for deer; deer congregate starting even before dusk and can be seen all night.  Undoubtedly the damage to the seedlings was deer-centric, probably by bucks trying out their new antlers and finding tasty snacks in the process.  Based on the severity of the damage, I am not sure that sturdier tubes and support poles would withstand the abuse any better than the netting and bamboo.

Construction - Interior Framing, Air Sealing and More

The temporary protection for the shell of the building, as described in detail in a prior post, gave me the opportunity to proceed with the interior partitioning before the roof was in place.  I was able to get almost all of it done when it was too inclement to work outside -- cold during the winter months and wet during the spring -- and before having finally to postpone inside work in favor of the dirt work and landscaping described in the several posts preceding this one. 

(The original pictures below can be enlarged merely by clicking on them but, unfortunately, the downloaded pictures are not enlargeable.)

T-wall with door opening.  Single 2 x 4
header (blue); blocking to support T-wall
(red); carefully fitted OSB behind T-wall
stud for gluing drywall for a tight air seal.

Interior Partitions
While the exterior walls are anything but typical, the interior walls are more conventional.  What makes them somewhat different is the use of as much advanced framing as possible and building most of them in place in order to fit the slope of the cathedral ceilings more accurately. Advanced framing, as opposed to traditional framing saves material (and its embodied energy) without compromising structural integrity. I was able to use it to support T-walls with horizontal blocking and single 2 x 4s for headers above doors in non-bearing walls.  Anticipating the need for more rigidity to carry heavy 36" solid oak doors, I did however stay with tradition by using jack studs at door openings.  Even at that, the open floor design with its fewer doors required only 12 additional door-height 2 x 4s for the jacks.


Exterior Partitions
By contrast, the truss-built exterior walls required twice as much lumber as traditional 2 x 4 walls but I can easily live with it since all of the lumber was recycled and the energy savings from the thick

walls will soon compensate for any higher inputs.  In retrospect, I would probably have used the advanced framing technique of metal plating to join single top plates rather than using overlapping double top plates, particularly since there are two courses or tandem 2 x 6 double top plates on top of walls that were already so wide as to stand unsupported when raised.  Using half as many top plates not only would have saved lumber but would have made the wall marginally more energy efficient by removing half of the potential for thermal bridging through the top plates.  I say, "marginally" because the tandem top plates will be separated by 4 1/2" of insulation as a thermal break.


Advanced framing for outside corners in 2 x 4 and 2 x 6 exterior walls have just two studs instead of the traditional four (see drawings). The abbreviated design not only saves material but also accomodates more insulation in the corner. 

Our truss walls carry the latter concept 

A single 2 x 4 in an outside corner; also notice the
rough window units to the left before being covered
 over with sheathing and boxed in as described below

to a new level -- there is only one stud in the corner and the cavity for the insulation continues around the corner totally uninterrupted.

Wall-Roof Interface

Without raised heels, the rafters would be resting directly
 on the double top plates; the heels raise the rafters out
 of the way so the insulation can be piled higher

The nearby photo shows raised heel trusses for a conventional ceiling whereby the rafters are a good distance above the top plates in order to provide space for insulation that is only slightly shallower near the exterior sheathing than at the drywall side of the wall.  Raised heels that rest on the inside top plates are especially beneficial for our cathedral ceilings.  The arrangement means that the space for the insulation is at least the same thickness on top of the wall as it is throughout the entire truss bay.  Another advantage is that the wall sheathing continues upward onto the trusses to help brace and anchor them. 

View from within a truss bay.  Raised heels (red) resting
 on double top plates (blue);  blocking to support the
junction between wall and roof sheathing (yellow);  
"L" shaped blocking (between the heels) for gluing the
 wall and ceiling drywall for optimal air sealing

The top cords for our roof trusses did not extend past the plane of the wall and therefore did not help form the soffet (overhang) as shown in the photo above for a traditional roof.  A previous post on the ventilated cathedral ceiling describes how the junction between the wall sheathing and the roof sheathing was blocked on the inside and taped on the outside for maximum  air sealing, then a "mini-attic" or "cool roof" was built on top of the first layer of sheathing,  In the process, the rafters for the secondary roof extended outward to form a soffet with a 2' overhang.

Blocking for Air Sealing
The junction between the wall drywall and the ceiling drywall throughout the house is backed up by blocking so that the edges of the drywall can be glued or at least caulked (presently I can't decide which is best) to give a better air seal than is typically possible with conventional construction.  Also, as shown in the top photo, OSB blocking behind the T-wall studs makes sure that the vertical edges of the drywall on the exterior walls are also

Example of "L" shaped blocking
that was cut from a 2 x 4
(depicted by the green arrow in
 the photo above and the left
red arrow below)

 sealable.  The goal for air sealing is to have the edges of all drywall lining the envelope of the building backed up so they are not only positively fastened with screws but are either glued or caulked as well.


Window and Door "Framing"
I am using this section to describe the unique construction of the window openings in the walls.  But, since the windows will be deeply recessed, I am also veering away from construction long enough to discuss the role of the recessed window design in enhancing thermal performance. 

The "framing" for the doors and windows in the thick exterior walls was a time-consuming challenge.  (The quotes around framing acknowledge 

that the process was more about using OSB to create a box within the wall to house a window or door than using dimension lumber to "frame" the opening in a typical fashion.)

As covered in a prior post, the dimension lumber part of the framing the for windows was done in jigs many months ahead of time then the pre-built units were set into the walls as they were raised.  Each pre-made window unit had horizontal supports under the window, spanning the width of the 

Continuation of air seal blocking around the corner of the
ceiling (red arrows); wall trusses (yellow); roof trusses
(blue); tandem double top plates (green)

wall, that positioned the window 3 1/4" closer to the inside surface of the wall than to the outside surface.  The outside sheathing and the inside drywall plus the decorative framing around the window on both the sides of the wall will make the total wall thickness around the window about 18".

With the window offset 3 1/4" towards the inside, the jam on the outside of the window will be about 8' wide plus another 1 1/2" for the frame.  Consequently, the surface of the glass will be recessed by almost 10" from exterior plane of the wall which, from an energy standpoint, has two advantages .  

First, the shadow box effect will block the summer sun in the early morning and in the late afternoon when it is low enough to shine under the overhang above the windows.  This configuration will be especially advantageous in September and early October when the sun's trajectory moves sufficiently southward to shine under the overhang a little longer each day. Blocking sunshine at this time of year is a plus because it is not yet needed for passive solar heating and could make the temperature in the house uncomfortable.  

Boxing in the second floor clerestory window openings. 
The raw pre-built window units are in the foreground and
 the boxed-in units appear in the distance.  The mullion for
 the partially boxed middle pair of windows has been 
insulated with EPS around the two horizontal 2 x 4s that 
support the sides of the windows 

Wind Washing
Another advantage to the shadow box configuration for the windows is that it ameliorates "wind washing". In one of its iterations, the term describes the movement of heat through window glass in cold weather.  The story goes like this.  Heat seeks cold so it conducts through the glass.  The conducted heat 

Windows installed with nailing flanges are nearly flush
with the plane of the wall

warms the air next to the glass such that the heated air lingers on the surface of the glass and slows the transfer of more heat through the glass.  The ability of the warm air to linger and "insulate" the glass depends on wind action.  On windy days, the heated layer lingers less.  The faster it "washes" away, the faster heat is lost through the glass.  New construction windows with nailing flanges have the thermal advantage of excellent air sealing between the rough opening and the installed window but are more susceptible to wind washing because the plane of the glass is virtually flush with the plane of the wall.  Our shadow box windows will not only reduce wind washing per se but, by facing south, will also be in better position to shield the glass from the north and west winter winds.

Mullion Insulation 
In most instances, our windows are to be paired but, instead of ordering the mullions between the windows factory-installed by Pella, I requested individual windows so they would be easier to handle while working alone.  Doing so meant that a mullion the width of a 2 x 4 had to be built into the window units initially.  Then, when boxing in the window openings, I added 3 horizontal 2 x 4s to the mullions for secure fastening of the sides of the windows.  As shown in the photo above, this arrangement created compartments in the mullion that would be inaccessible when the rest of the wall was insulated with rice hulls that I filled with rigid Styrofoam board.  As a result, the mullions should be warmer than would have been the case with factory mullions.

Construction - The Next-to-Last Major Section of the Insulation/Watershed Umbrella

For once Mother Nature cooperated despite it is the rainy season.  With help from a few volunteers we were just able to carry the installation of the umbrella behind the house near enough to completion that a pair of spring rains did not affect it.  A few days later, we completed it and moved on to final backfilling, grading and planting.  (Reminder:  clicking on any picture enlarges it for better viewing.)

Water Control
There are two considerations for water control behind the house -- surface water and water that soaks through the soil to reach the level of the umbrella.  The former would comprise most of the water from rainfall were the grade sloped enough to encourage quick runoff.  But the fall of the final grade northward from the house will be only 2 - 3' over a distance of about 100' -- a very gradual slope that will nicely handle runoff without erosion but one that will give the runoff more time to soak into the soil.  At a distance from the house, the quicker soak time will be less consequential but, over the umbrella, it means that the surface of the umbrella will handle more water.

Hiat's Design
The umbrella in front of the house sloped much less than 

the one behind the house. The rain that soaks through the soil overlying it slowly finds its way off the umbrella and down the hill away from the house.  By contrast, the rain that will soak through the soil covering the umbrella in back of the house needed to be handled by a French drain so as to direct it down-slope around the east and west sides of the house instead of flowing northward away from the house where it might pivot and undermine the umbrella.  Therefore, the umbrella slopes more severely and has a French drain at its periphery as Hiat describes in his book, Passive Annual Heat Storage.*  The idea is get the water away from the house before it can soak into the soil beyond the umbrella and flow back under the umbrella (which was its natural tendency before the lot was excavated).

As for the composition of the umbrella, it is exactly the same as described in a prior post for the front umbrella except that it was complicated by the conduits for the AGS system sticking out of the ground.  As in previous sections of the umbrella, the extruded polystyrene foam board insulation is thicker near the house and thinner towards the periphery of the umbrella.  For the first 8' from the house, the thickness is 4" (R-20); for the next 4' the thickness is 3" (R-15) and for the last 8' it is 2" (R-10).

Installation
The umbrella is bracketed on the east and west sides by

West retaining wall underway thanks to several volunteers

substantial retaining walls made from recycled limestone foundation stones.  The east wall was installed last fall; the west wall had to be done before work on the umbrella behind the house could begin. 

In addition to the layer of insulation, there were three layers of 6 mil plastic sheeting.  Our initial experience with the first layer and the foam board over it taught us that both the sheeting and foam board slid away from the house as we worked.  So, special precautions were necessary to anchor all layers until anchored with backfill.  We used a couple of dozen of 12" galvanized spike nails driven through the foam and into the ground in

First layer of plastic and the insulation in place with layers
of sand to serve as a drainage plane in case water leaks
through the top two layers of sheet plastic

strategic locations to hold the insulation tight against the house.  Of course, this meant poking holes in the plastic sheeting under the foam but, since it will be protected by two additional layers of plastic, the holes were a good trade-off for stable and tight insulation.  

In order to keep the two top sheets of plastic from creeping down-slope during installation, we turned their edges upwards at the wall and attached them to the bottom edge of the wall sheathing using batten boards.  Also we spread a layer of sand between the sheets so it served as a counterweight against the wind for the first sheet until the second

Recycled carpet in place; sand had not yet been added
to the edges of all of the carpets (as seen in the
background for some)

sheet could be installed and more sand on top of it held it down until the recycled carpet could be laid over it.  The primary reason for the sand, however, was to provide a drainage plane for any water that makes its way into the lower layers of the umbrella.  Despite all of the effort, varying amounts of space existed between the horizontal foam and the wall that we discovered after it was too late to fix.  If I were to do it over again, I would anchor the foam boards with twice as many spikes before covering them with plastic rather than after the sheeting had been attached to house then bunched up against the house to get it out of the way of anchoring the foam after the fact. The plastic prevented us from knowing for sure that the foam was tight against the wall when spiked.

Sealing the Pipe Holes
We had to cut holes through all three layers

of plastic sheeting and through the 2" thick portion of the insulation to fit around the conduits.  Those in the sheeting were invariably stretched when the plastic was lifted and slid down over the pipes, such that they did not even come close to sealing out water.  So, just before installation of the carpet, each conduit was fitted with a thermoplastic roof vent flashing for 4" pipes.  The space under each flashing was made as smooth and clean as possible so that the weight of the backfill would press the rubber-like flashing tight against the sheeting to keep out water.  The holes in the carpet were cut with a hole saw turning backwards on a cutting board that had a hole in it to accommodate the centering twist drill. 

French Drain
The depression for the French drain at the northern periphery of the umbrella was a V-shaped ditch that drained both ways from the

Final grade for the umbrella including the ditch for the
French drain

center, i.e., it was deeper at the ends than in the middle.  The bottom layer of sheet plastic completely lined the ditch and its loose edge was pinned to the soil beyond the ditch so that water will be confined in it until it can find and escape via the drain.  Unfortunately, the ditch undermined the last course of foam board to varying degrees.

The design of the French drain itself was similar to that described in a prior post on French drain fabrication for the drains we installed early on 10' below the floor of the house.  Luckily, I still had a roll of the geotextile material used for the original drains, one that is unique in filtering out the kind of fine

Perforated pipe laying on geotextile material and partially
embedded in sand ready for closure

silt characteristic of  the wind-blown loess here in the bluffs of the Mississippi River.  We rolled it out along the length of the ditch and laid a 4" perforated drain pipe on top of it.  We then shoveled sand alongside the pipe, pulled the edges of the fabric together, rolled them three times and clipped them together with hog rings as described in detail in a prior post. In doing so, we made sure that the pipe was tight against the ground side of the fabric and the sand loosely filled the space on either side and on top of the pipe.

Since the last course of foam board partially bridged over the ditch, it had to be supported somehow before it could be covered.  Accordingly, we filled the ditch with

French drain closed with hog rings

sand to the level necessary to support the foam's cantilevered edges, which, at the same time, improved the permeability of the medium around the fabric-covered French drain.  With the foam supported, we could extend the sheet plastic over the insulation, add the carpet and begin backfilling in earnest.  In order to be sure any water coming off the umbrella found the sand around the drain before it could be dammed or slowed down by the backfill soil, we made sure the edges of both the plastic sheeting and the recycled carpet (that forms the top layer of the umbrella) were amply covered with sand.

Unique Insulation Design
The prior to the AGS concept, insulation for earth contact homes was fastened to the concrete wall.  Hiat was the first to suggest taking it off of the wall and laying it horizontally in order to create a much bigger conditioned thermal mass for the house.  He was a purist to the extend that the roof of the house would be earth sheltered and the umbrella would be merely an outward extension of the insulation on the roof.  In our instance, the roof is conventional so the relationship of the wall insulation and the umbrella had be handled differently.

Accordingly, as detailed in a prior post, the top 30" of the concrete wall situated under the stick-built portion of the wall is insulated to an R-14.  (In time, the top 30" inside will be similarly insulated.)  The insulation in the umbrella (R-20) butts up against the wall insulation (eventually R-28) at about midway of the latter's vertical dimension, such that about half of the wall insulation lies above the umbrella and about half lies below. 

Ideally perhaps, the umbrella insulation should 

Spreading topsoil

be R-30 near the wall instead of R-20 but I accepted Hiat's word that any additional loss of heat through the umbrella next to the wall will be offset by the heat saved by extending the umbrella a full 20' out from the wall. 

Planting
 As soon as the final grading was done for the large area north of the house, topsoil was distributed and planted with grass seed as a means of controlling erosion in the short run. The original intention was to plant several dozen bare-rooted hardwood tree seedlings in the newly graded area but the subsoil under the topsoil ended up being largely hardpan (glacial till) in which trees do not grow well.  The turf grass will control erosion until it can be replaced with native prairie species that are not at all picky about soil quality.  Gradually the turf over most of the rest of the property will also be natively landscaped in the manner that Doug Tallemy crusades for in his book, Bringing Nature Home; How You Can Sustain Nature with Native Plants, which I referenced in an earlier post on native gardening.  
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*  Hiat's book is out of print but a few copies are still available on online.  For an understanding of his design for the umbrella, go to my prior post that discusses it in detail.  The same post is part of the trilogy on Annualized GeoSolar conditioning that can also be accessed indirectly by clicking on the "Featured Post" in the left column above.