Progress this week has been steady. Contrary to our expectations we found the soils to be coarse sand with no moisture at the bottom of the excavation. We formed and poured the footings, and have set the Insulated Concrete Forms (ICF) for the foundation walls in preparation for a pour tomorrow. The plumber, well contractor, and HVAC contractor have installed sleeves in the wall for sanitary and water supply lines. A basement egress window is framed in the foam.
The foam walls have an R value (the ability to Resist the transfer of heat) of 24. We will be adding another three inches of foam to provide a total R value of 38 for the wall assembly. The ICF form is an 8’ long by 18” deep collapsible form which gets good production, low shipping costs. The form is reversible, and scrap pieces as small as 2” can be used to minimize waste which is recyclable.
For reinforcing steel there are two #5 bars in the footing and a 2’ x 4’ grid of reinforcing steel in the walls. These are locked into the ICF forms in clips provided in the form design.
We were fortunate to discover a company by the name of The Insulation Depot (insulationdepot.com) which recovers insulation from roofing tear-offs and manufacturer end runs. They have about 50 warehouses around the county where they capture, store, resell, and ship the material at about half retail cost. The material is slightly damaged, but any imperfections can be filled with spray foam.
Insulation Depot never knows what their inventory will be from one day to the next. Our project would have been best served with 2” high density extruded polystyrene (XPS), but they had a manufacturer’s end run of 1” tongue and grove which will require a little extra handling.
We are planning to install cement stucco on the perimeter of the home. As this is an expensive and labor intensive operation, we are planning to contribute a little sweat equity. We will be taking the opportunity over the next couple of weeks before we backfill the foundation to develop our stucco skills on the foundation walls. I will write more about the stucco materials and process in a later issue.
With the very permeable soils, we are not concerned with water infiltration and have modified the foundation waterproofing specifications. Originally we intended to install a peel and stick membrane. With the low probability of any problem, we will experiment with installing used EPDM rubber roofing membrane. In addition to being used and in need of attention, there are two drawbacks to EPDM roofing material. First is that EPDM is vapor permeable, but if it directs water to the footing drains instead of through the basement wall we can live with that. The second issue with EPDM is UV degradation from sunlight which will not be a problem in this application.
A couple of our local commercial roofing contractors retain roof membrane from re-roofing projects and give it away to anyone who is interested. People use it to roof their hunting cabins, or as liners in landscaping ponds. We had already planned on using this material for the stormwater collection system, and this fits in very nicely with the materials re-use ethic.
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