Radiant floor heating system

Foundation insulation and waterproofing

Truckload of insulation

Fill 'er up

Installing rebar

Foundations are done

The foundations were poured last Friday without incident.  We used a concrete mix design with a high percentage of fly ash.  This power plant waste product acts as a lubricant to make concrete slipperier when poured into the forms.  The technology has been around since ancient Rome (volcanic ash); however fly ash has recently been determined to be toxic.  Fly ash is not a problem as long as it remains in place, but if the home is ever torn down, it may require remediation efforts. 

The insulation that arrived was a little the worse for wear.  We received a 53’ semi-trailer with 12 pallets of 1” insulation stacked about 8’ high.  It took three of us an hour to unload and stack the material, consuming a large portion of the site.  About 10% of the material was unevenly extruded, or not cut to exact widths or lengths.  We used this material in areas where it made the least difference, saving the better material where performance and appearance are more critical.  Much of it could be cut off to fit as needed, but clearly additional labor is required for this option.  There is a significant first cost savings if you have the sweat equity to invest in cutting and fitting.

The plumbers and HVAC contractors got their sleeves in the wall.  We installed the footing drains, sump crock, and most of the waterproofing.  Reality struck when we attempted to use the rubber roofing for the waterproofing that I speculated on last week.  The rubber EPDM membrane was extremely heavy, the age was indeterminate, holes were not detectable, and we only have one opportunity to get the waterproofing on the foundation walls right.    We will be using the used membrane roofing for the rainwater harvesting system which is easily accessible, and minor leakage poses no risk.  

We opted instead to install a rubberized membrane with self adhesive properties.  This over an additional two inches of insulation that we fastened to the ICF forms with 4” screws and fender washers.  We will install another one inch of insulation over the top of the waterproofing to act as a protection board against damage from backfilling the basement.  This will provide us with the total R value of 38 that our energy model requires. 

We installed a 10 mill plastic vapor barrier on the basement floor that will also act as a radon barrier.  The 10 mil plastic is also reputed to last longer than the standard 6 mil vapor barrier.  Our energy model showed us that we need 8” of rigid insulation under the slab in the basement.  The 8” of insulation went on top of the plastic, and we stapled a 5/8” Pex (plastic) pipe on top of the insulation for our radiant floor heating system.  We should be able to finish installing the basement insulation and radiant floor heating in time to pour the concrete slab on Monday.