Katrin Klingenberg Visits the Site
Posted from: MD, USA
We have accomplished a lot since our last post.
First, we laid a 6” gravel bed down over the soil. This provides a capillary break between the concrete and the soil, preventing the slab (basically a big sponge) from sucking up moisture from the soil below. Standard good construction practice.
After the gravel was tamped level and compact, we placed 4” of EPS Geofoam over it. The EPS boards were laid tight together, with no gaps. One of the photos is taken just as the vapor barrier was about to be laid. You can see the foam is held back to allow the concrete slab turn down and rest directly on the concrete footing at its perimeter. Another picture shows the basement grinder pump set in its insulation bed. Mid Atlantic Foam took the crock and the radon crock to their shop and fabricated foam cradles for them. Bartley Concrete then simply made a depression in the gravel, and set set the cradles with their tops flush with the top of the rest of the foam, and dropped in the equipment.
While the foam was being put down Bartley was also applying the waterproofing membrane to the exterior of the sub-grade foundation wall. In one of the photos you can see the membrane going down to the top of the footing. The temporary foam form has not yet been removed. When it is, they will apply the waterproofing with a roller all the way down the sides of the footings as well. Friday the 3rd was a big day. After all the sub-slab foam was in place, Bartley installed and taped the vapor barrier. We also had a surprise visit from Katrin Klingenberg, Director of the Passive House Institute U.S!
The pictures show the 15 mil Stego polyethelene vapor barrier (http://www.stegoindustries.com/technical_info/_stego_wrap_15-mil_vapor_barrier.html) all laid out and taped up. We chose the StegoWrap over the standard 6 mil barriers because you have to really want to cut it or tear it in order to do so. Draping it down under the footings and up the wall, we wanted to be sure nothing inadvertently punched holes in it. All joints were taped continuously, and as you can see in the photos, all penetrations were fully double-taped as well. We temporarily tacked the edges up along the foundation walls until the slab is poured. Bartley will then come back and anchor a continuous metal termination bar along the top, mechanically fastening the barrier to the concrete. Katrin was in DC doing a training course for Passive House consultants. (http://www.passivehouse.us/passiveHouse/PHIUSConsultantsTraining.html) Of all days Katrin could have come, this was the best. It was a first for all of us at taking these extra steps of sealing, and having her go over our work and pronounce it first rate before the concrete went in gave us all a big boost.
On Monday, after Keith made a final check of all the taping, the concrete trucks rolled up and poured the floor slab. I dropped by the site today and include a picture of the finished slap, with only the top of the vapor barrier peeking out. Another picture shows the same penetrations we photographed earlier, now encased in concrete and sealed tight. The group in the picture, left to right:
Keith, Katrin, Brendan Jr., and Terry Hill, another Passive House consultant.