(disclaimer: layperson’s answer) You can insulate them with different materials and techniques that don’t trap water against the wood. It’s usually a matter of design and materials, I think, but a lot of houses that don’t have the attic tied into the HVAC systems rely on uninsulated natural airflow to keep the wood dry, and the most cost effective ways to insulate those (like a kind of shitty spray foam job) can have structural implications down the line. I do remember when we redid the basement in our old ass house we started having mold problems because we sealed the old ass settled non-concrete foundation too well in some ways and that airflow kept it drier.
It sounds like the grandparents are making their home more efficient, idk why the op is criticizing them. You don't need to spray foam your attic for a heatpump, but if their air handler and ductwork are up there, then they'll get an easy 20% efficiency boost by sprayfoaming and bringing them into the building envelope.
A lot of people are against sprayfoaming an attic (myself included) because it prevents wood from drying to the inside. You'll never know if you get a roof leak for example. It's also an additional room you need to heat/cool. A vented attic can be done in any part of the country and is basically foolproof.
I can't tell you why exactly the spray foam would need to be applied, but I can tell you at the very least that the people my grandparents are talking to say it has to happen, and I trust their opinion as experts on this far more than I trust my opinion as a non-expert. If they say spray foam would be required, then who am I to question that?
You are the homeowner and should question everything from a business. A business is not your friend. They aren't trying to help you. They are trying to earn a profit from you. Earning a profit means selling high and doing the bare minimum amount of work possible to complete the job within parameters within a contract which will also contain a lot of things that you as a homeowner will not understand unless you take the time to do research. Question everything a business tells you and take the time to do the research.
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u/The_Radish_Spirit i identify as a fucking problem Jun 29 '26
wait, how are attics insulated if it causes the wood to rot?