Sunday, June 26, 2016

Construction - Garage Floor; Addition of Earth Contact East Wall

The garage floor was not poured at the same time as the house floor.  One reason for the delay was to kick the cost of it down the road.  But the major reason was that it would be doubling as a part of the insulation/water umbrella and I was not ready at that time to commit mind space to its exact design.  As noted below, the garage was under-excavated simply because I had not given an umbrella-floor combination enough thought.  

Reality Check
Progress on the entire house-building project has been and will continue to be snail-paced mostly because of the limited amount of work a DIYer alone can accomplish. The agreement I had with the Building Director when applying for a permit is that, since I was responsible for the design of the house, the architectural drawings did not need to be as detailed as is typical.  The upside of this arrangement is lower architect fees but the downside is that I have more stuff to keep track of on the fly. Not committing mind space to the garage floor at the time the site was excavated is a perfect example of how difficult it is for one person to prioritize and coordinate the myriad facets of construction.  Some things have to be back-burnered until they are more pressing and some simply drop through the cracks.  

Finally, the time came when the garage floor had to be dealt with and, by delaying, I created extra labor to get it right.

The original excavation would have been pretty accurate if it were not necessary to install the insulation/watershed umbrella under the floor as that part extending eastward from the house proper.  But the excavation needed to be lowered at least by the thickness of the foam insulation board for the umbrella.  So I tried to catch the soil at just the right time after a rain that it worked easily with hand tools -- which leads into an interesting discussion about our unique bluff soil.

Factoid About Our Unique Soil
In-letting for 4" of foam insulation
Smooth sand base for the insulation
Most of the soil covering the bluffs originated in the Mississippi River flood plane where it was deposited by receding glaciers.  The finer particles in the deposit were picked up by the wind and dropped on the bluffs (which themselves were left standing by the glaciers). The fine-grained silty soil, called "wind-blown loess", is extremely rich and drains reasonably well except that, when it dries out, it is almost as dense as plaster-of-paris and hard to work with.  Underlying the loess at depths that vary greatly throughout the bluffs, is a layer of what the local soil conservation agent calls "glacial till" and what we old-timers call "hardpan".  It is a layer that, when it is dry, is almost impossible to penetrate with hand tools. It is a layer that I had to dig through with the trackloader when excavating the hillside for the house such that the loader was often over-matched.  However, both the loess and, to some extent, the hardpan are somewhat more manageable if one catches them between the mud and dry stages.  Hence, my hesitancy to start digging until after a rain.   

Insulating the Garage Floor as Part of the Umbrella
Middle section of insulation in place
The foam board insulation under the garage floor needs to be 4" thick for the first 8' from the house then 3" for the next 4" followed by 2" to complete the coverage.  I started the inletting for the foam with the first 8' next to house.  When it was reasonably accurate as to depth and levelness, I coated the soil with enough sand to be able to make a smooth bed for the foam.  I laid the insulation in place over the wide footing next to the wall, stood foam board against the leading edge of the footing then installed two layers of  2" thick XPS in the new excavation.  To stabilize the foam and protect it from the wind temporarily, I covered it with a little more sand. Eventually, more sand would have to be added before the floor could be poured; more on this later.

Final section of insulation in place
Next, I hand-excavated for and installed the middle 3" section of insulation.  The 2" section was handled in the same fashion. Finally, I added sand in lifts and hand-compacted them after soaking the sand with a lawn sprinkler to make it more compactable.  By the time Jamie Schultz and crew came to do the pour the sand had dried to the extent that I soaked it thoroughly the night before so they could compact properly with a plate compactor just before covering with plastic and pouring the concrete.

Raising the Height of the East Wall of the Garage
In retrospect, I should have designed a higher concrete east wall for the garage in order to
Rebar and door buck in place for adding four feet to the
height of the east wall; notice also the 2 x 10 forms bridging
the garage door openings
have more flexibility for contouring the final grade of the soil east of the garage. The more I tried to justify leaving most of the wall stick-built, the more it became apparent that a higher concrete wall was necessary.  Consequently, on the day that Jamie Schultz and crew came to pour the slab for the screened porch (previous post), they erected forms and poured a four-foot high wall on top of the insulated concrete foundation.  The cost was probably twice what it would have been at the time the rest of the walls were poured.

Pouring the Garage Floor
The floor was designed to be 1 1/2" lower than the house floor at the back of the garage and 3" below at the front.  I snapped chalk
The new east wall uncovered (in the background);
the slab pour underway
lines on the back wall and along the side foundation walls to mark the height of the pour. Across the openings in the insulated concrete forms underlying the garage door locations, I installed 2 x 10 forms to confine the concrete and for screeding at the 3" level.  

When Jamie and crew arrived, they removed the wall forms and, while waiting for the ready-mix truck, plate-compacted the sand that I had soaked the night before and installed 6 mil plastic sheeting.  The day was warm so the pour cured rather fast and could be finished by early afternoon.

Handling the Cold Joint Between the Wall Addition and the Foundation
My design and management of the east wall of the garage was driven too much by cost.
There are three deadmen in the middle of the north wall;
the fourth and fifth are affected by turning the corners
and involving the east and west walls
We turned the north wall southward into a short section of east wall in order for it function as one of the critical deadmen for the long north wall that was to be backfilled without internal support.  I should have had the entire east wall of the garage poured in concrete by at least half way up in order to have more flexibility for managing the grade east of the house.

The disadvantage of retrofitting the east wall is that a cold joint is formed between the concrete of the insulated concrete form foundation and the new wall.  My concern was that the joint would leak water into the garage.  So how to fix it?

One possibility was to gunk up the joint on the exterior with tar-like materials and hope that
they would not lose their effectiveness with age, assuming they adequately sealed the joint in the first place, given the contamination of the surfaces by deposited dirt. The other possibility was to install a proper French drain opposite the joint to siphon water away before it could infiltrate the joint.  I oped for the latter.

Typical French Drain Installation
So I more or less followed the typical protocol for French drains albeit with some customizing in order to use up some left-over materials. After the ditch for the drain was dug, I threw in a few inches of sand to level the ditch and to deepen the drainage plane below the drain (first photo). Then instead of buying pre-perforated corrugated pipe with a geo-textile sock already on it, I used some pipe left over from the solar collector conduits and geo-textile material left over from the French drains that under-gird the house.  I used the same technique for perforating the pipe that I had used early on for converting culverts to French drains (DIY French drains made from culverts).  I also used the same technique for attaching the material to the pipe as I used with the culverts. 

There was already a footing-level French drain so it was a matter of  uncovering it and inserting a wye for the new drain (first photo).  I then lined the ditch with left-over geo-textile fabric and fastened it to the wall temporarily (second photo).  As is typical with French drains, I covered the bottom of the fabric with a couple of inches of  3/4" clean rock before laying in the pipe and connecting it to the wye (third photo). More rock was added to cover the pipe.  The edges of the fabric were overlapped to cover the rock and secured with hog rings (third photo).

The drain was left exposed instead of backfilling immediately because the outside of the garage wall will have to be insulated before the soil is added.  It will be insulated in the manner that was described in an earlier post .  As soon as the wall is insulated and covered with stucco, I will backfill nearly to the top of the wall at the back and sloped towards the bottom of the wall at the front.

The footing French drain for the west and north concrete walls, as well as the east wall into which I tapped for the new drain, was not as carefully done because it will be covered by the insulation/watershed umbrella and the backfill sloped so severely away from the house that it is unlikely that it will ever see water once the umbrella is in place.  It's function, besides meeting code, is to siphon off enough water to eliminate hydrostatic pressure on the walls while the uncompacted backfill settles on its own before the umbrella goes in. 

Consequently, I used home center perforated pipe with a sock, no fabric lining for the ditch and sand instead of rock for the drainage plane.  If there were to be no umbrella, I would have bought perforated pipe and covered it myself with the geo-textile material shown here that has been scientifically designed for fine silt soil like we have.  The store-bought fabric that I did use instead of the special fabric can be expected, in the absence of an umbrella, to admit enough silt to clog the pipe and render the drain useless eventually.  The same would be true for lining the ditch with local store-bought material -- it would not filter the silt sufficiently to keep the gravel bed clean and unclogged indefinitely.

Sunday, June 19, 2016

Construction - Screened Porch Floor

This post focuses on the next-to-last phase of the concrete work, viz., the screened porch in front of the house.  Remember that you can click on any photo to enlarge it for a closer inspection.

Footings and Foundation
I over-excavated the soil next to the house to the level of the foundation footing and then sloped it downhill in order that the insulation/watershed umbrella can installed on top of the footing and sloped downhill enough to drain well.  In the process, the soil under what will be the concrete floor for the 14' x 16' screened porch on the front of the house was also over-excavated.  In order to compensate for the over-excavation, the footing for the porch foundation was much taller than it was wide on the downhill side which complicated forming it up for the pour.

I mimicked the forms we used for the 8" tall footings under the house foundation by using
Forms for the footings
some of the same salvaged 1 x 8s and the same lightweight braces. As a result, 
we almost had a blowout because the bracing and the 1 x boards were too weak and barely able to hold the weight of so much concrete on the tall downhill side.  Consequently, the footing after the forms were removed looked pretty amateurish. 
Poured footing; notice the bulge just beyond
the corner due to a near blow-out

I thought I had learned my lesson and made sure the forms for the short foundation wall on top of the footing would be, if anything, over-engineered.  Wrong! Despite robust 2 x 4 framing for the plywood form walls, we almost had another blowout.  As soon as we started the pour, a wall started bulging due to weakness of the spreaders that tie the two sides of the form together across the top.  Instead of using 1 x 4s and two 6d nails on each side, I used 1 x 2s and one 16 ga 2" nails from a nail gun. We had to stop the pour while I  added several 1 x 4s in the most susceptible areas and re-nailed the existing 1 x 2s with 6d nails.   If I were to do it again, I would use 1 x 4s and regular nails for the spreaders throughout and 2 x 4 stakes for all of the braces because they can be driven with a sledge hammer to a greater depth than the 2 x 2 stakes that I drove with a heavy hand mallet.  Fortunately, the wall did turn out to show a little less amateurism than the footing.

Poured foundation 

Before the slab can be poured, the backfilling must be continued until the cavity inside the footing and foundation is filled
Backfilled with sand to the height of the footing prior to
installing insulation
to within 5" of the finished floor level in order to support a 5" thick slab.  Also the foundation wall must be insulated in order for it to function as a shallow frost-protected foundation. Then insulation must be used horizontally under the floor as part of the watershed/insulation umbrella.
Accordingly, I used sand to fill the cavity to the top of the footings in lifts (layers).  The sand was not wet enough for proper condensation so I hosed it down before condensing it with a manual compactor.  A good overnight rain finished the compaction.  In retrospect, I should have borrowed a friend's plate compactor for better compaction with less effort.

Insulation As Part of the Insulation/Watershed Umbrella
Over the sand, I layered mostly EPS but some XPS foam board following the
Horizontal and vertical insulation starting at the level
 of the top of footing
recommendations of Hiat, i.e., 4" thick for the first 8' out from the house then 3" thick for the next 4' followed by 2" thick. This 4-3-2 pattern was also used for the garage floor as described in the next post. For the rest of the subgrade umbrella on all sides of the house, the pattern changes to 4-3-2-1 in order to reach out a full 20' from the house. 

In order to satisfy the requirements for a shallow frost-protected foundation, the porch foundation must be insulated on both sides.  Inside, I merely stood EPS against the wall. For the outside, I will eventually install expanded polystyrene insulation board 2 1/2" thick supported by metal drywall track and covered with
Form for cantilevering the slab outward
with rebar to support the edge
parged cement board.  (This process was previously discussed in the recent post on the first retaining wall.) For a finished look, the slab will will be cantilevered out over the concrete of the foundation by at least 3" in order to cover the insulation and parged cladding. To this end, I built a peripheral form that would allow the slab to overhang the wall by the width of a 2 x 4 and controlled for height of the slab by way of  2 x 8 sideboards.  In order for the floor to drain southward, the sideboards were installed at the same height as the house floor next to the house then angled slightly downward such that the floor will fall 

1 1/2" over a distance of 15'.

Final backfilling, ready for 6 mil plastic and concrete pour
Slab Floor
After the insulation was in place, I covered it with a thin layer of sand to isolate it from the wind and to buy some time while another rainy period passed.   When the weather permitted, more sand was added in lifts and each lift hand-compacted until nearly flush with the foundation wall, thus leaving space for a 5" thick slab.

Completed slab for screened porch with cantilevered edge
Six mil plastic sheeting was fitted over the sand on the day of the pour. Jamie Schulte, the contractor that had previously poured the wide footing for the tall concrete north and west walls, the walls themselves and the slab for the house, returned to pour the porch floor first then to pour the forms for raising the height of the east wall of the garage.   The next day he came back to pour the garage floor.  The garage pours are the subject of the next and last post on the concrete phase of construction.

Wednesday, June 1, 2016

Construction - Pre-made Exterior Window-Housing Wall Sections

After considerable research on windows and doors, I decided in favor of Pella fiberglass casement windows and fiberglass doors. (For more details on window selection, see a previous post on window design.) The building code specifies that the total window area be at least 8% of the livable floor area.  Furthermore, 4% of the windows must be operable plus egress-friendly in rooms, such as bedrooms, that do not otherwise have direct access to the exterior.  Our passive solar design that situates all but one small east window in the south wall meant that, to meet code, the windows would have to be large and bunched together.  We meet code by utilizing 9 pairs of windows plus one unit of three windows with each window 3' wide and either 5' or 6' tall.  The size of the windows automatically render moot the egress requirement.

The Pella rep was somewhat taken aback when I specified individual windows instead of enjoying the advantage of pairs of windows being joined at the factory with fiberglass mullions as is typical. There are a couple of reasons for keeping them separate.  First, it would be impossible for me, working alone, to install two heavy windows in one piece -- even the individual windows will be a challenge. Second, cost is reduced by about 10%.   

So let me share how I went about using mostly downtime caused by bad weather to assemble in the shop the wall sections that will house the windows.  Eventually, the sections will in interspersed with individual trusses for a wall thickness of 15" insulated with rice hulls to an R-50.

Jigs To Standardize the Wall Sections
Fortunately, there was enough room on all sides of the table saw to use it to support a jig of about 7' x 8' in size.  I would have preferred to use salvaged lumber for the jig but quickly learned that it was too non-standard. Therefore, I used new lumber to insure that all wall sections would be identical -- square, plumb and level.  And I found out by trial and error that it would take mostly new lumber to standardize the wall sections as well.

It took two jigs to make a wall section.  The first one on the saw (top photo) was used to cut and fit the side of the assembly facing the interior of the house then the cut pieces were disassembled and set aside. Then the same jig was used to cut and fit the side facing the exterior which varied with the interior assembly only in the window sill area.  

The next task was to join the interior and exterior assemblies.  This was done by removing from the saw-top jig the 2 x 4 on the left side of the exterior assembly and matching it with
the left 2 x 4 for the interior assembly that had been set aside earlier. They were transferred to the truss jig that was described in detail in a prior post on wall trusses (second photo).  The left interior and exterior 2 x 4s were nailed together to form a truss then the truss was moved  back to the saw-table jig. The right interior and exterior 2 x 4s were similarly nailed together in the truss jig and returned to the saw-top jig. The final step was to fasten all of the individual pieces together in the saw-t jig to make a three dimensional wall section.

The wall sections will not be needed for a couple of months so it became imperative to protect them from the elements, particularly since some of the gussets for the trusses were OSB.  I tried first to wrap them in stretch wrap but soon realized that was folly -- it was hard to accomplish and it leaked even in light rain. Instead we moved all of the sections onto the house floor and thoroughly enclosed them with plastic and battened-down tarps.  

The OSB pieces that will line the window openings were cut and stored separately with the intention of adding them later after the walls are raised, thereby reducing the weight of the sections for easier handling and delaying their exposure to the elements as long as possible.  In the same vein, I am erecting the weight-bearing interior walls before assembling the exterior truss walls so as to be able to get the exterior walls under cover as soon as possible after they are in place.