Sealing and insulating hatchway to vented attic
davidsmartin
| Posted in Green Building Techniques on
My attic is now insulated with 18″ of cellulose. The builder left a hatchway from a closet in case we need to access the attic — it will not be used for storage, just for access if something goes wrong. The builder suggested using a piece of plywood with a couple sheets of foam insulation on top to cover the hatchway.
Does that make sense? How can it be air sealed so that it is not a chimney sucking up warm air? Would weather stripping suffice?
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Replies
I'm a DIYer not a pro ...
First, your question makes it sound like there is nothing other than a hole in your closet ceiling. That's crazy and has to be fixed and shouldn't be your problem if this is a new build.
Second, why didn't your builder fully address this issue? I'd be concerned about what other air sealing work he left you.
Third, if you are mostly concerned about air leakage, you could look into a zip cover if weather sealing isn't cutting it. Years ago, I made a cover for a whole house fan on the interior side out of plywood, foam, and foam weather strips. Pretty it was not but it was in the utility room and it did work.
Fourth, did you have a blower door test done? I'd do that before doing anything else. If it is grossly deficient, bring it up with your builder. Perhaps the house is already tight enough.
What climate zone are you? How much insulation is up there?
That's what I've got. Maybe the pros will have more advice
Sorry that my explanation was not clear. This is an addition to my house that is under construction. Two days ago they blew the cellulose into the attic. They built a sort of box around the opening to keep the cellulose from falling into the closet. My builder plans to insulate and seal the hole but has not yet been specific about how he plans to do it. If people here have suggestions I am confident that he will be receptive.
David,
First, I'd like to discuss terminology. What you call "a sort of box around the opening to keep the cellulose from falling into the closet" is usually called an "insulation dam."
What you call "a piece of plywood with a couple sheets of foam insulation on top" is known as an "attic access hatch."
An attic access hatch needs:
1. A rigid panel (often plywood) that faces the interior of the house.
2. Several layers of rigid foam, glued to the panel, with a total R-value of at least R-38.
3. Weatherstripping between the rigid panel and the lip that supports it.
4. At least two latches that pull the panel tight to the weatherstripping.
Here is a link to an article on the topic: How to Insulate and Air Seal an Attic Hatch.
Thanks Martin for the clear explanation.
Re point 4, latches of some sort are a great idea. I like the idea of adding sash locks (like you'd find on a double hung window) to pull the panel tight to the weatherstripping. If, for some reason, latches are deemed undesirable, I've heard of people adding two layers of scrap drywall to the top side of the (R38+) rigid foam to give the panel a bit more weight to help compress the weatherstripping.