Friday, October 14, 2011

Frost heaving and cold bridge fixing in foundation wall


Last fall we got a new big sliding door to our garden deck. During the winter we had problems opening it, probably due to frost heaving. Our carpenter suggested we should insulate the outside of the concrete slab that the house is built upon. This concrete is also a nasty cold bridge into the house floor. So I got the spade out and started to dig.




The concrete slab is about 50 cm ( 2 feet) deep, at least around the perimeter. I also removed the lower plank to make sure to expose all of the concrete.








Today it is common to add 5 cm ( 2 in) of styrofoam insulation to the foundation wall, so I decided....










...5+5 cm should be good. I think it is a good idea to add as much insulation as possible while at it. I managed to cover all the exposed concrete.











Then there is an issue of leading any water away. So I added some fabric, "Leca balls" and a drainage pipe.









Close it up.











I also added 60cm of 5 cm thick styrofoam from the wall and out. This will also help to insulte, and will later be hidden under the new deck that will reach all the way to the sliding door. All set for the winter! When it gets real cold, it will be interesting to compare inside floor temerature close to this wall  to similar positions close to walls with no foundation wall insulation.
Update: It turned out that the problem with the sliding door was the upper wood above the sliding door that twisted during the winter. Some additional screws have now solved that problem.

Summary in Norwegian: Vi har installert en stor skyvedør mot hagen i vårt rekkehus fra 1978. Forige vinter begynte den å gå treigt, antagelig på grunn av telehiv. Dermed gikk jeg i gang med drenering og isolering av betongplaten som hele huset står på. Hensikten er å unngå at det blir frost under denne, og å fikse den enorme kuldebroen det er å ha sementgulvet i stua koblet rett ut i kuldegradene utenfor. Isolasjon er ikke noe man skal spare på, det er bare å kline til med det det er plass til. Her ble det 10cm mot veggen og  5cm plate 60 cm ut fra veggen. Til sommeren kommer vår nye hage platting her oppå isolasjonen i bildet. Andre steder i hagen planlegger jeg å få hvertfall de 10cm mot muren. Gleder meg til å se hvor varmt gulvet blir der hvor det er ekstra utvendig isolasjon i forhold til der hvor det ikke er.