Odds 'N Ends - Carbon-Phobic Homes Come In Many Stripes

The "Energy" Component in Green Building

The best summary I have seen on levels of energy independence is found in the introduction to Johnson and Gibson's "Toward a Zero Energy Home - a Complete Guide to Energy Self-Sufficiency at Home". The book is a good read for anyone interested in sustainability--it is full of success stories for both new construction and remodeling.  They differentiate between net zero energy homes, off-the-grid homes and carbon neutral homes. 

Net Zero Energy Homes

These homes produce as much energy as they consume.  They are tied to the utility grid with net-metering, have photovoltaic arrays or wind turbines and store any excess production on the grid rather than in batteries.  The utility typically pays a fair price for the energy it gets when the house is producing more than it is using.  However, some utilities drop the price to a pittance once net-metering reaches zero.

Off-the-Grid Homes

These homes live on an energy budget.  When production exceeds usage, the excess goes into on-site batteries that have a limited storage capacity.  If the sun isn't shining or the wind isn't blowing and the batteries are running low, there's a problem.  The solution is lifestyle adaptations that ration or manage energy usage.  Toasting bread for breakfast and taking a hot shower simultaneously might not be possible.

Carbon Neutral Homes

A carbon neutral home carries zero energy to another level.  It produces enough energy, not just to handle its daily needs, but to cover the costs of building the home in the first place.  This means covering the embodied energy in extracting, manufacturing and transporting the building materials to the home site (which, according to Johnson and Gibson, is 8% of the home's energy use).  Only the most principled and ethical home owners go there (which is hard to do anyway if the utility refuses to pay a fair price after net-metering reaches zero).

Passive House Movement

According to the authors, the Passive House Movement began in Germany in 1990 based upon passive solar research in the '70's by the U S Dept of Energy, spread rapidly across Europe and finally made its way back to this country in '03.  The first net zero energy Passive House was built in Urbana, IL where the Passive House Institute U.S. is located. According to the Institute, the standards for Passive Houses are as follows:

• Use of the Passive House Institute software to model the house
• Super-insulate
• Eliminate thermal bridges
• Make the house airtight
• Use heat-recovery ventilation
• Optimize passive solar design
• Use high-performance windows and doors
• Use internal heat gain (people, appliances, electronic equipment)
• Zero out energy needs with renewable energy (my addendum, based on the authors' discussion following the list in the text)

Can We Call Our Project "Net Zero"?
With exception of the first standard listed above (we did a DIY design without software), our home will exceed the Passive Home standards......so I guess it's safe to use the term "net zero" energy, or at least "near zero" energy to describe it once it's finished and the photovoltaics have been added.  And we will take great pride in achieving net-zero at a fraction of the cost of typical new construction -- green or otherwise.

Design - Footing and Foundation

Footings and Foundation Walls

The footings are not negotiable when pricing construction costs; they are whatever the construction engineer signs off on.  The foundation wall, on top of the footings and under the stick-built walls, is another matter.  In an attempt to cut costs, I costed out several scenarios.  But first, how deep do the footings need to be?

In order to meet code for frost protection in our neck of the woods, the bottom of the footings should be at least 30" from the finished grade.  Under a wood wall, then, the foundation would have to be 30" minus the height of the footing, usually 8".  Then 8" has to be allowed between the grade and the wood members for termite protection.  The minimum height then would have to be 30" - 8" + 8" = 30".

Design similar to ours (minus footings)

Frost Protected Shallow Foundation

However, there is a green alternative called "frost protected shallow foundation" (frost protected shallow foundations).  At least 2" of solid foam insulation is attached to the exterior vertical concrete then more is laid horizontally outward from the wall a few feet.   The horizontal insulation rests on top of the footing (a footing is not shown in the nearby drawing but can be seen in the Amvic pic) and is covered with soil up to a depth allowable for termite protection.  This means that the height of our wall, instead of being 30", can be as short as 20" as follows:  8" for termite protection, 10" for backfill over the insulation and 2" for horizontal insulation.

Amvic Building Systems ICF Technical & Installation Manual

Insulated Concrete Forms

The 10" difference in wall height for the foundation may not seem like much but on a tight budget it is significant.  We will be using insulated concrete forms (ICFs) (our likely choice for ICFs).  They are are stacked in interlocking fashion as a form for pouring the concrete then left in place after the pour to provide 2" of permanent insulation on both sides of the wall.  The cost savings for a 20" wall versus a 30" wall is one third, or $950, for a 163 linear foot wall like ours.  That's 1.31% of the total budget that can be used for something else. And concrete and Styrofoam are not exactly sustainable materials so using less is a green alternative.

Parenthetically, the insulation, watershed umbrella for the AGS system (last of three posts on AGS) lies tight against the ICF on top of the footing and therefore satisfies the requirements for the exterior horizontal component of a frost protected shallow foundation. 

Other Options

I looked at other foundation options in an effort to pinch costs even more but came up empty.  Complete Blocks (Complete Block Company), though tempting, were too expensive despite an offer from the owner for free installation.  Dry-stacked cinder blocks or concrete poured in rented conventional forms were in the ballpark with ICFs but less DIY friendly and, to achieve a thermal performance comparable to the ICF's, an insulation design would have to be improvised, would be labor intensive and would have an outcome very likely to be inferior to that of the proven ICFs.

North Wall
The north (back) wall, which is critical for the AGS system,  will be in contact with the earth to a height of 12' and, because of an interior wall design that accommodates a storage room next to the wall, it will not be well braced against backfilling--essentially mimicking a long straight retaining wall.  Unless something can be worked out with Complete Blocks, there were no sensible alternatives to a 12" thick conventionally-poured concrete wall seriously-laced with rebar and resting on out-sized footings.

Timeline - Gathering Sustainable Materials (Cont'd)

 Three Years Ago

Left-over timbers

Limestone Foundation Stones

The barn that step-son, Keith, and I finished salvaging provided a few good timbers to do what he wanted to do in his house.  The few that were left over have weathered too long to be structurally useful but may offer possibilities for re-sawing.

However, the limestone foundation under the barn was invaluable (similar stones are sold by the pound by landscape material dealers).  The foundation went deep enough to be below the 

Unearthing the foundation stores

frost line and was dry-stacked rather than mortared.  A vendor with a mini-excavator and a track loader dug up and piled the stones then used his loader to load dump trucks.  In all, there were four tandem loads estimated to be 65 tons total.  As you may have seen in a previous post, Gathering Sustainable Materials, many have already been put to good use weighting down the barn "tin" covering the stacks of salvaged lumber.

Second of four tandem loads

Retaining Walls and Pervious Pavers

Eventually, the large stones will be used for retaining walls and the smaller stones to pave the driveway.  However, Collinsville recently passed an ill-advised (from a sustainable standpoint) ordinance specifying concrete or asphalt for all new driveways.  The justification for it was "to control dust", according to a recent conversation with the City Manager, (yeah, right, people race and do wheelies on their driveways).  I am determined to get permission to create a pervious drive with stones interspersed with a soil-sand-gravel mix that will sustain native grass that is durable enough to drive over (and control dust (heh, heh)).  The pervious drive will bisect at least two rain gardens that will also be planted with natives.

Working with Big Stones is Hard Work, But........

I don't exactly look forward to working with big stones, some of which are at least 200 pounds, but I am intimidated by what the farmers must have gone through to assemble the original foundation for the barn.  They would have had to dig by hand, or with a horse-drawn bucket, a trench wide enough to work in and about three feet deep.  They would have had to haul 65 tons of limestone with horse-drawn wagons from a quarry located somewhere in the Mississippi River bluffs ten miles away.  And think about the difficulty of unloading the stones and dry-stacking them in a deep ditch in such a way as to support  a barn.   I have a hard time imagining how strenuous it must have been and how long it must have taken.

Gotta Be Creative

There is a good chance that the track-loader will have been sold by the time some of the retaining walls and drive are done.  We may therefore have to improvise some way of getting the stones from the stone pile to where they are needed.  This is step-son, Keith's forte--I am sure that, with his help, something creative will happen.  It may be a mini-derrick on bicycle wheels or a drag line off of a wheelchair (similar to the one he made for handling logs) or god knows what.

Enough  bricks remained for our entryway floor.

Salvaged Brick
The fly-by-nighter who left the barn timbers to weather away also took most of the antique soft bricks from the farm house (he cherry-picked the barn tin, the barn wood and the antique bricks, leaving the rest for someone else to clean up). Fortunately, we were able to salvage enough bricks for "tiling" the entry way/air-lock to our house. 

Recent update:  The brick floor for the entry was scrapped because the concrete floor in the area would have to be at a different level than the rest of the house in order to accomodate the bricks and doing so would up the contractor's price for pouring the concrete.  We may now use the bricks for a half-wall in the living room.

Timeline - Gathering Sustainable Materials

Beginning Four Years Ago

We will be buying very few lumberyard materials for the house; most will be either salvaged or fresh-sawed hardwoods.  It will be this in combination with DIY labor that will contribute the most towards meeting our tight budget (budget and estimate).

First house; the owner had already begun the tear-down 

Salvaged

Beginning four years ago, I have dismantled board-by-board three old houses, two garages and several farm out-buildings.  The boards have been de-nailed and stacked under cover.  As an example of the size of the cache, there are over 400 2 x 4s seven feet or longer plus hundreds shorter than seven feet. There 

Second tear-down owned by the City of Collinsville

are all of the 2 x 6s we think we will need. There are 2 x 8s, 2 x 10s and 2 x 12s.  There will be enough one-bys to sheath the exterior walls and enough fir flooring for one upstairs room, not to mention a bunch of old-fashion stained (not painted) wainscot.  And I have picked up a few free lots of lumber from Craigslist.  

My step-son, Keith, and I finished salvaging the timbers from a 19th century barn after a fly-by-nighter knocked it down for its barnwood and tin roof then left the timbers unprotected.  We were able to use some of the better timbers for the house we built recently for Keith and Dawn.  Few of the rest may be salvageable for re sawing. Next spring, we will obtain, for the price of freight for a few miles, up to twenty timbers that support the floor of early 20th century house that our friend is tearing-down.

Third tear-down -- a combination of house, garage and out-buildings

Sawmill lumber

When we were interring my son's ashes in the family plot in my hometown Walnut Ridge Cemetery in 2011, I noticed that a huge nearby walnut tree (probably dating from the mid-1800s and probably helped to give the cemetery its name) was sickly.  I inquired about it, found that it had been struck by lightning and needed to come down.  The cemetery board said it was mine if I paid to have it removed.  The timber guy was happy with $200 to fell it and haul it to the saw mill.  The mill guy was happy with $250 and let me guide the custom sawing of the big logs.  Step-

Half of the main walnut log on the sawmill

son, Keith, and I used his smaller mill to saw up the limbs, some of which were as thick as many saw logs.  The outcome was over a thousand board feet of choice walnut that has been air-dried and stored under cover.  The walnut is destined for kitchen cabinets, dining room furniture, built-ins and we don't know what else yet.

During the winter of 2013, I purchased and helped saw up about the same amount of red oak.  It is "stickered" (stacked for air-drying with tiny boards separating the layers of lumber) and stored under cover.  The oak will be used for all interior woodwork, doors and stairway -- at a cost of about $3,000.

Red oak "stickered" for air-drying

Legal Concerns

There are liability issues associated with doing a potentially dangerous tear-down on private property.  The second house I dismantled was for the City of Collinsville whose City Attorney drafted a document that absolved the City of liability.  It also spelled out respective responsibilities as to deadlines, ownership of salvage, dumpster rental, disconnecting utilities and filling the basement afterwards.  I used the City's document as the template for a generic document suitable for the other properties I salvaged. 

Salvaged lumber stored for proper air circulation -- off the ground, leveled, covered with metal and stickered between alternate layers.  The stack to the left with the ends painted white is the walnut stickered for air-drying.  Click on the image for a closer look.

Proper Storage of Lumber

We naively started out storing the denailed boards close to the ground on 4 x 4s, 6x6s and railroad ties under tarps.  Not good!  Fortunately, we found the termites while they were only eating the scrappy 2 x 4s and reconfigured our storage methods. Four years later, I can recommend the following storage technique.

1.  Spread ground cloth -- geo-textile fabric or old carpet, carpet pads or tarps -- to control weeds and discourage varmints and insects

2.  Use concrete blocks (ours were salvaged from the tear-downs) to support 2x cross-members on which to rest the lumber;  space them about three feet apart across the stack and four feet apart longitudinally 

3.  Use a long straight edge and plenty of wedges to make sure the supporting 2xs are level longitudinally (level across the stack is not important except for sheet goods)

4.  Use stickers (1 x 2s or narrower) about 2' apart between every other layer and lay in the boards so that there is at least a half-inch gap between adjacent boards, thereby assuring that each board has at least three sides exposed to the air (for air-drying sawmill lumber, the stickers go between every layer and are closer together)

5.  Cover the stack with salvaged metal roofing panels or the equivalent rather than wrapping the stack with plastic sheeting or tarps, again so that air can circulate freely through the stack; a certain amount of water infiltrating the edges and ends of the stack when it rains horizontally is tolerable as long as there is exposure to the air

6.  Weight the metal down with heavy stones or concrete blocks; use plenty, don't underestimate the heft of a 50 mph wind.  As an insurance policy against tornadoes, consider running heavy gauge wire around the stacks in several places and tensioning it enough to secure the stack (since tornadoes are unpredictable, it might also be a good idea to offer alms to the gods, if not your firstborn).
7.  If space permits, position the stacks wide enough apart to accomodate your lawn mower so as to minimize weed-eating.

Recent update:  As of the end of 2016, most of the dimension lumber had been used up and I can report that the suggestions offered above proved valid.  There were a couple of instances of carpenter ants ruining a few boards but I have yet to see any termites.  If I were to do it over again, I would take the time to use stickers for every layer instead of every other layer to minimize trapped moisture between boards that could foster mold alnd encourage ants.  Although it was not a big problem, I did end up saturating some boards with undiluted vinegar to kill mold before using them.  And there were a few instances, when it was just easier to ditch a board than to disinfect it.

Design - Trenching and Back-filling

This post was written at an early planning stage whereby I intended to minimize cost by doing most of the work myself.  When it came time actually to do the trenches for the French drains and the AGS conduits, we were in the midst of the rainiest Spring in history. It became necessary to get as much work done as possible between rains so we enlisted professional help for the trenching as well as for grading for the slab floor.   It took several posts to cover the installation of the French drains and AGS conduits. Here are links to those posts:  First post on French drains, Second post on French drains, Last post on French drains,  First post on AGS system.

Despite their irrelevancy, I am keeping the following paragraphs posted to demonstrated how ridiculously naive a DIYer can be when venturing into new areas.  

Safe Trench Work 
Nothing has kept me awake more than vacillating over the best way to dig the trenches for AGS conduits and the French drains then backfill back to floor level with enough compaction to support the house.  The French drains ideally should be about 10' below floor level in order to make sure the soil around the AGS conduits, at three to five feet below floor level, stays dry at all times.  

According to OSHA (A guide to OSHA Excavation Standard), it is not safe to work in a trench deeper than four or five feet even if it is pretty wide.  Above five feet, special precautions have to be taken that do not fit our budget.  The type and water content of the soil, the weight of nearby dirt piles and the use of heavy equipment in the vicinity are some of the variables that go into safe trench work.  To me as an amateur, this means that, if we intend to enter the trench, it should be no deeper than five feet, wider than is intuitive and vacated after heavy rains until the soil drys out. Or the trench could simply be used without entering it, which seems to be the best choice for the several reasons discussed below.

Back-filling
After the trenches are dug, they have to be back-filled and compacted enough to support the house.  The soil is clayey silt left behind by the glaciers.  It reliably supports structures only when left undisturbed, which is quite impossible with the amount of trenching we need to do.  Once disturbed, silt is difficult to compact even with proper equipment and ideal moisture content (US Military Field Manual FM 410, Chapter 8 in which Table 8-3 unequivocally recommends against our type of soil as back-fill under weight bearing structures).

Trenching Plan
Coming up with a plan for trenching and back-filling has involved a lot of online research, calls to equipment rental companies and consultations with a backhoe professional and a civil engineer friend (our soil engineer died before we had consulted him fully).  The outcome is that we will modify the original plan that was elaborated in Excavation and Excavation (Cont'd).  

Instead of using the track loader to cut trenches 5' wide and up to five feet deep for the AGS conduits, the trenches will be 8' wide.  Then 

DIY-friendly mini-excavator

the trenches for the French drains can be dug in the middle of the wider trenches with a rented mini-track-hoe.   The 8' wide trenches will serve three purposes:  (a) Provide plenty of space for the mini-track-loader, (b) allow placement of an AGS conduit at each edge of a trench thereby separating them by 8' or so and (c) allow French drain depth of no more than 5' but still positioned 10' below floor level.
However, we have decided on a radical departure from the typical design for French drains discussed in an early post Excavation (Cont'd) in order to be able to use a narrow trench safely and to minimize as much as possible the amount of backfilling with clayey silt.  

The typical drain is about a foot in cross-section, filled with gravel, a 4" perforated pipe with a geo-textile 'sock' running through it and wrapped on the outside with more geo-textile fabric. Therefore, the entire assembly can be visualized as nothing more than a crude 12" "tube" protected by fabric.

Customized French Drains

Second load of culverts

Accordingly, we have decided to use, as French drains, 8" ID corrugated plastic culverts wrapped in geo-textile fabric -- no gravel, no 4" pipe.  They will be pre-assembled by perforating the sides of the culverts, joining the 20' sections with couplers and wrapping the entire assemblies with fabric before lowering them onto a shallow beds of sand in the narrow trenches using ropes from above. The sand will allow us to use rakes from above to finesse the 1% fall for proper drainage (How to Slope a French Drain).  We will use hog rings to clamp the fabric.together after wrapping it around the culverts and before adding the ropes. Each of the seven drains will be at least 70' long.

Geo-textile Fabric Designed for Silt

A comment by the soil engineer (before he died expectantly) to the effect that our French drains would clog eventually with silt, despite the use of filter fabric around the pipes as well as around  the gravel, caused me to investigate geo-textiles online. Fortunately there was one excellent study (Research on geo-textile fabrics) that shed light on fabrics used with silt, which is the type of soil we are dealing with.  As a result, we ordered from Carthage Mills the fabric that tested best for use with silt, viz., woven fabric - 30% open area, pictured nearby as it arrived on the pallet.

Back-fill Plan
Footings and a slab floor should rest on undisturbed soil.  Unfortunately, there will not be much undisturbed soil left after excavating for the French drains and the AGS conduits.  Rather than do all of the back-filling with the excavated soil, the plan is to fill only the narrow French drain trenches with soil and, if it is too dry, attenuate it with limestone dust to draw moisture out of the air and make the soil more compactible.  The French drain fill will be compacted in "lifts" of no more than 8" using a borrowed plate compactor.  Alternatively, we may decide to backfill the narrow trenches with rock as described below for the wider trenches.

Rather than back-filling the wider trenches with the original soil and risking inadequate compaction for supporting the house, we plan to utilize the type of gravel, recycled from concrete that is used as a base under concrete highways.  It is cheaper than quarry gravel and a greener alternative.The fill will have to be built up in lifts of +/-6" and compacted with rented equipment, either a self-propelled steel roller vibratory compactor or a remote controlled roller.  Back-filling will stop at about the level of the soil that was left between the trenches initially.  Then the entire excavation will have to be prepared for the slab which is the subject of subsequent post.