Passive House Footings Are Different

Posted from: MD, USA

To prevent thermal bridging (short circuits in the insulation system)
the complete building envelope of a Passive House is insulated. In our
case, this includes the footings. In this little film clip you can see
that in progress.

After excavating the trenches for the exterior wall footings we put
down a “mud slab”— basically a thin coating of concrete over the
earth which could then be trowelled level. That gave us a nice flat
surface to lay our insulation down on. We then put down 4” of high
density expanded polyethylene (EPS) foam.The concrete is then poured
over that.

The sides of the outside wall footings will be insulated with 4” EPS
as well. You can see the white EPS on the interior face of the
footings. It does double duty as a form for the concrete. On the
exterior side of the footings you see the insulation is a different
color. This insulation board is used as a form for the footing and
will be removed. Why? Because we are waterproofing the exterior walls
right down to the sides of the footings. Once the concrete walls are
poured, we will apply the waterproofing membrane, then come back and
insulate the entire wall and sides of footings with the EPS foam. The other two footing photos show the footing for a pier inside the house before and after the concrete is poured.