05:38PM | 11/16/05
Member Since: 01/15/05
3 lifetime posts
Our kitchen bumps out 2 feet from the rest of the house. (This is above a walk-out basement. So the floor is 8ft above the ground) The bottom of the joists that stick out from the house are covered with soffit. If I look through the vent holes in the soffit it looks like there are boards "boxing in" the bottom of the joists.

What's the best way to insulate this area? The floor is ice cold in the winter. Does it need ventilation? Or can I seal it up with foam board and then put the soffit back on?


04:46AM | 12/22/08
Member Since: 12/21/08
1 lifetime posts
I have the exact issue as boscoBob. But I don't see any replies??


04:15PM | 01/07/09
Member Since: 02/21/07
1 lifetime posts
I have the same issue and have looked at numerous sites without any success, anyone have a solution?


05:29PM | 11/14/13
I've read two solutions. 1.) drill holes, blow in insulation, or if accessible from lower floor, insulate from there... make sure there is no air flow that needs to be stopped before insulating w fiberglass. 2.) if the bumpout is connected to the lower level, and the lower level is heated, REMOVE some insulation so that the warm air is able to circulate into the space below the bump-out floor.

Duane, Moderator

10:12PM | 11/14/13
Member Since: 11/14/13
87 lifetime posts

I would recommend to remove the vented soffit under the bump out and inspect the area for gaps or holes, if any wiring is located in that area make sure the hole where it penetrates the bottom plate is sealed with caulking.
You then want to look into proper insulation for the floor.
There are different r-values required for various geographical areas, you will want to go to
Once you have found the correct r-value you can insulate the floor of your bump out solve your cold floor issue.
I recommend closed cell insulation, class works well in regards to resistance to heat flow, however foams also helps to seal air gaps as well.
The framing should also have blocking between the floor joist over foundation wall, reinstall vented soffit for proper ventilation and you should see a improvement.

I hope this helps,
Duane Cotton expert moderator
Build America Construction INC


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