Tuesday, March 10, 2020

Construction - Steel Siding and Soffets; Garage Doors

As early as mid-2015, we weighed several options for cladding and decided that steel siding would be, by far, the most sustainable.  In a previous post, I said.........

Steel siding is ...... "DIY-friendly, it's virtually maintenance-free, it lasts for plus or minus a century and it has a recyclable end-life. If there is a knock against metal siding, it is that it has fairly high embodied energy which,to some degree, is off-set by its recycled content".

In the first of two posts early in 2019, I described our adventures with buying steel roofing from Menards and followed it with a second post on its installation.  Our steel siding also came from Menards so the following discussion covers only the installation although its purchase was not without additional adventure as well.

As an aside, let me point out that installation of the steel roofing can be a one-person job, at least if it is not too windy, because gravity is an ally.  Installation of steel siding is another matter because gravity is the enemy.  Even with a trim piece at the bottom of the wall on which to stand the sheets while aligning and fastening them, tall panels are virtually unmanageable working alone.  And, for a watertight junction between panels, it is absolutely critical that the overlap between panels be fitted precisely before fastening -- something that is a little more difficult to do by one person.

Moisture Barrier
Joseph Lstiburek, in his excellent paper on vapor control, recommends using vapor retarders, such as house wrap or 15# felt, rather than vapor barriers such as plastic sheeting, bitumen-coated Kraft paper and, as often recommended by steel cladding manufacturers, 30# felt.  For a summary of Lstburek's paper, check out a previous post on vapor and air barriers.

In keeping with Lstiburek's advice to use a vapor retarder, our best choices were house wrap or 15# felt paper.  I opted for the felt paper due to atypical dimensions of our walls.  The south-facing walls that were closest to typical were riddled with windows which would mean wasting a lot of house wrap if it were installed first then the window openings cut out.  The rest of the walls were less than the height of a roll of house wrap -- some only a few feet high -- which would necessitate pre-cutting the wrap instead of merely rolling it out on the wall and fastening it.  And, because the joints in the sheathing were taped against air infiltration, there was no need to use the vapor retarder as an air barrier so using large pieces of house wrap that minimized the amount of taping was moot.

Consequently, I chose to use 15# felt paper as the vapor retarder.  It was cheaper, easier for two people to handle, was better suited for the short walls on top of the earth sheltered walls and could easily be customized to fit around the windows that were clustered together and also easily adapted to the sloping tops of rake walls.  We overlapped the courses by at least 6" to thwart moisture infiltration.  We taped the seams between courses with Tyvek tape, not so much as an air or moisture barrier, but to keep the wind from having its way with the felt before we could cover it with steel which proved to be only marginally effective.  Despite fastening the felt with roofing nails instead of stapling it, it pulled loose in a few areas, had to be re-nailed and the pull-through holes in the felt healed with Zip tape.

In retrospect, I would have sprung for the extra cost of the wider and stickier Zip tape that I used to seal the roof and wall sheathing instead of the Tyvek tape.  Not only would it have better protected the edges of the felt from the wind, it would have adhered better and prevented vapor penetration through overlapping edges the felt over the long run -- maybe overkill but why-not?

As is standard procedure, we used "J" trim at the left and right vertical edges of each section of wall into which the edges of the first and last panel fit as well as on each side of the window and door openings. Then any moisture circumventing
Steel "J" mold used at the edge of steel panels to divert
water downward that will eventually be overlapped and
covered by painted wood trim
the edges of a panel is diverted downward.  In order to make the house look less like a commercial building or rural implement shed, the "J" trim will eventually be overlapped by and hidden behind wood trim.  The top edges or panels below the windows
though not ending in J trim, will likewise be hidden behind wood trim.    Most of the trim will be fashioned from pressure treated 2 x 6s,\ and 2 x 8s, being mindful that pressure treated stock is typically stored wet at the lumber yard and, if not handled right, shrinks and warps as it drys.  I found early on with the mud sills under the walls that pressure treated lumber can be rendered dimensionally stable by drying it on stickers for several months, exactly like air-drying sawmill lumber.  In fact, at the time of this writing, I was already installing the trim.

The bottoms of most of the second story panels
Friend, Glen, is laying out the location of a row of fasteners
In this view, notice several things:  the rows of overlapping
15# felt paper taped together, the cedar trim board over-
lapping the termite shield with the bottom steel molding
 between it and the lower ends of the steel panels; the cedar
 board and the molding give a cleaner, less commercial
 look than if the steel panels simply terminated over the
 edge of the termite shield (click to enlarge for better detail).
overlapped the dormer flashing at the wall-roof junction.  For a more finished look, the bottoms of most of the first story panels rested on a trim piece called "bottom trim" in lieu of having them merely overlap the termite shield slightly as is probably more typical. On the front of the house, as an aesthetic upgrade, we overlapped the top edge of the termite shield with a 5/4 cedar board then rested the bottom trim on it.

Customizing the Steel
In a previous post, I described a jig for assembling trusses for the exterior walls of the house.  Eventually, I modified it as a jig to support the steel roofing while custom cutting. Then I expanded it for cutting the wider siding steel panels.  The manufacturer warns against cutting the panels with power tools, like circular saws or grinding discs, that produce red hot fragments (sparks) that burn spots in the finish of the metal, opening the way for rust.  Instead, we found that metal blades in a cordless jig saw do cut rapidly without making sparks.  The only caveat is that, in order to control vibration, the panel has to be clamped securely to the jig while cutting .  Fine-toothed blades with 30 teeth per inch minimized vibration and still cut reasonably fast.

The extra effort going into making a jig for
The width of the jig that was used for cutting the roof
panels was modified to accommodate the wider siding
 panels; the crosspiece on the near end was used to press
 downward on the panels in order to control the vibrations
caused by the jig saw.
cutting metal panels is definitely worth the effort.  However, its rectangular shape is not ideal for cutting the angles associated with hip roofs and rake walls because the panel is better supported the short side of the cut, than the long side that overhangs the end of the table more.  We tried modifying the table with an angled extension which helped but was suitable only for angled cuts in one direction while hips and rake walls needed to be diagonalized in both directions.  We finally simplified things by using the square end of the table for all cuts.  We used a specially-designed crosspiece at the end of the table for  downward pressure to control vibration.  Sometimes we supplement it by additional clamping.

We padded the foot on the jig saw to keep it from scratching the finish on the panels but two problems caused us eventually to cut all panels upside down.  The duct tape we used for padding left smudges and occasionally the tape would wear through and scratch before we realized it.  The disadvantages of upside down cutting, though, is that the layout for angled cuts is more un-intuitive and takes more concentration and the table must be thoroughly cleared of metal fragments that might scratch the front of the panels.

Fastening the Panels
The self-threading hex-headed fasteners that matched the color of the panels came with elastomeric grommets under their heads. The challenge was to drive the fasteners just enough to compress the grommets to the proper degree.  Squashing them either too much or not enough could compromise the water-tight seal under the fasteners.

Metal Soffets
The ventilated soffets were also made of steel. 
Intersecting longitudinal perforated steel
soffets framed with recycled lumber (yet
 to be painted); notice the Rain Handler
 System (arrow) in lieu of a conventional 
gutter and downspout system.
(Click on picture to enlarge for details.)
Instead of short multiple pieces running cross-ways between the fascia and the wall as is typical for most soffets today, the steel comes in long lengths that are 16" wide.  Since the soffets are 24" wide on the house and 36" wide on the porch, it was necessary to frame the metal panels with wood -- wood that, in a former life, was fir roof sheathing on a house that I salvaged previously .  By rabbeting one edge of the wood, the edges of the panels could be tucked under the framing and, 
for a better seal against insects, caulked where necessary.

Rain Handler System
In order merely to disperse the runoff from the roof instead of directing it to a few places using a gutter and downspout system, we used the Rain Handler System.  With a 2" overhang of the steel roof panels, the water falls onto the perforations in the Rain Handler and, essentially, becomes rain drops again before falling to the ground.  The dispersal adds moisture to the shallow backfill over the insulation/watershed umbrella that, because of its lack of volume, stores less moisture to nourish plant life and can use the extra water collected by the roof.  The two places where we did use conventional gutters was a short section over the front entry and another on the side of the porch under a roof valley where the amount of water often overshot the Rain Handler and eroded the soil below.

Garage Doors
Installation of the garage doors was a new experience for me but the manufacturer's detailed instructions made it relatively easy.  I will focus here only on the extra carpentry that was necessary to provide support for the ends of the tracks and the garage door openers in the presence of a vaulted ceiling.

We used a couple of long 2 x 4s that were
Boxes appended to the beam for supporting the closures
(green arrows); notice the one large window instead of
smaller windows within the doors. (Click to enlarge)
(salvaged from a pallet on which steel roofing was shipped) nailed together to form a beam spanning the width of the garage and positioned to be +/-10" above the top of the door openers and aligned with the ends of the door tracks.  It is supported in the middle by a nailer dropped from a roof truss.  Boxes were added to it over where the closures would be located so that the closures could be hung with short lengths of perforated angle iron as would be typical with a conventional 8' ceiling.
 After going the extra mile to insulate the garage walls, floor and ceiling and to use insulated doors, it made sense to minimize the number of potential air-leaking penetrations through the ceiling drywall.  Using the beam meant that there would be only three penetrations as opposed to the 15-20 that would be necessary with individual angle iron supports for the rails and closures.  And the aesthetic difference is a nice plus.

We elected to forego windows in the overhead doors and go with a large window above them.  Doing so eliminates the weight of the glass in the doors and provides more privacy.  And the large window, to my eye, is not only more interesting architecturally, but seems to provide more useful solar gain in winter.

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