I have a 1969 built ranch home with a full basement. We live in the snow belt and this is our 2 winter in the home. The access to the attic is in the stairwell to the basement. I know from viewing the house when snow covered that there is significant heat loss there with the lack of or very little snow directly above in relation to the attic access. I also know that it can use a lot more insulation up there.
My question is, what is the best practice in insulating the attic? We do not store anything up there or have any need to.
A local spray foam company that came in and sprayed my rim joists when we moved in can vacuum the material and spray 2-3 inches and I can put loose fill or batt on top. Or do I just add more loose fill?
I like the air seal aspect of the attic know that there is more heat loss upwards than anywhere else.
Thoughts?
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You didn’t say what the access door or hatch is. Vertical, horizontal, door, hatch? Check out this advice for that: https://www.greenbuildingadvisor.com/article/how-to-insulate-and-air-seal-an-attic-hatch. As for the overall air sealing by vacuuming up all the insulation 1st, I’ll just tell you what I did in my attic. I moved the cellulose out of the way on 2 walls (the only easily accessible walls) and sprayed foam from a can wherever it looked like it needed it. I did the same at the 2 ceiling light penetrations. I didn’t agonize over the air sealing too much because our 1840 farmhouse has plaster walls and ceilings, which create a pretty good air seal. To save the hassle of bringing home a blower, I didn’t add more cellulose on top of the 6” already there, I put down R-30 un-faced fiberglass batts on top of it. Easy to manage and lay in place, for “roughly” R-50.
It is a horizontal opening with an attic ladder that lands on the stairs to the basement. A little bit of an awkward setup, but out of the way.
There are lots of YT videos on how to make a rigid foam insulated box that goes over the opening, above the ladder. This link also describes it. https://www.greenbuildingadvisor.com/article/how-to-insulate-and-air-seal-pull-down-attic-stairs
I think the first priority is to get the ceiling / attic sealed, to stop the air movement for the heated space to the attic. Given the age of your house, there are probably lots of other leak paths besides the attic hatch. Light fixtures, pot lights in the ceiling, exhaust fans, or any other penetration in the ceiling should be sealed. Electrical wires running through the walls to the attic are also a leak path.
Sealing each of the penetrations individually has a relatively lower materials cost, but more labor. Vacuuming the existing insulation and spray foam is thorough way of doing it, usually more expensive.
Some guidelines on how to seal the attic: https://www.finehomebuilding.com/project-guides/insulation/video-series-air-seal-an-attic
The attic hatch should also be made air tight. There are commercially available airtight hatches available for replacements, or you can build an insulated box around the hatch.
One way of doing it is here: https://www.finehomebuilding.com/2002/07/01/airtight-attic-access
Thank you for the suggestions and guidance.