Does anyone have a good detail for a new door sill that doesn’t convect cold air? (not the sill of the door assembly, the area directly below that the sill rests on)
I have a 150 yr old home – timberframe on stone-rubble foundation just outside of Toronto. While the existing front door isn’t that old (30yrs), there has always been a considerable draft in the winter months. The existing condition is a 2″x8″ wood sill resting on the rubble foundation wall. I have tried spray foam underneath etc…to no avail. Also, I have wrapped the foundation exterior with 2″ foam.
Now I am replacing with a new steel entrance door (gotta Love clearance sales!). But I don’t want to put the new door on the existing sill, I’d rather solve the problem! Be it pour a new cement curb below (isolate with s-foam), or whatever ideas you have…
Does anyone have a good detail/technique for building a sill that is draft free?
Thanks for any suggestions!
Charles.
Edited 8/29/2004 7:24 pm ET by chas
Replies
Pull the old sill and verify the solidity/integrity of the foundation wall. Get that as air tight as you can: parging, urethane foam, whatever works for your situation. Many drafts in this type of structure are coming in through the foundation wall and thence up through the floor.
For the sill: Build a small form and pour a concrete cap on the area of your foundation wall where the sill will sit. Before you pour, paint the top of the foundation wall inside the form with a concrete bonding agent such as Gel-Crete. This will avoid a cold joint.
If height allows, make the cap at least a couple of inches thick. If not, use some Fibreglas matting to reinforce the concrete and make it as thick as you can. Insert two or three J-bolts into the wet concrete. Once the concrete is dry and cured, push two strips of sill-seal on over the j-bolts, drill a new 2x8 sub-sill to match the bolts, and torque it down to compress the sill seal about 30-40%. You should see no gaps between the wood and the foam.
Obviously, you're going to have to counterbore so the washers and nuts are not proud of the top of the sub-sill. Make sure the threading on the J-bolts goes down far enough that you'll be able to get the nut below the surface of the 2x8; you may have to run a die down close to the bend considering that j-bolts are meant for foundation pours where the bolt can be inserted to any depth needed. Or just get some 3/8" threaded rod and bend it into an L using an oxy-acetylene torch.
Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
Hi Dinosaur, Thanks much for your advice...these are some great ideas. Conceptually I was thinking the same, but didn't know the detail.
You knew exactly what I needed to know!CHeers,
Charles.
You're more than welcome. And welcome to BT. The more the merrier....Dinosaur
'Y-a-tu de la justice dans ce maudit monde?
An "air lock" entry would help--basically a small foyer with a door to the outside and not directly in line, a door to the inside. That may help some. If you have forced air heat you can put a cold air return in front of the door so the draft goes down into the furnace to be heated. Before "modern" HVAC, many houses had the cold air returns on the outside walls, especially under windows for this reason. But modern thought was to wash these areas with the hottest air. But this makes the greatest Delta T (difference in temperature) right in the worst place because at the greatest Delta T, you lose the most heat. This happens because heat wants to warm the coldest thing (not exactly scientific, but...) first. I think there was wisdom in having the heat from the furnace come up the inside walls, flow along the ceiling, giving heat to the room, and then drop down along with cold air coming from windows and such into the return air ducts. Sorry for the rave.