Hi folks! I own a 1975 home with settled blown-in insulation in the attic. I've received quotes for adding more insulation to increase the R-value, but I've read that this might not be effective unless I seal the attic first. It will cost me $3,500 to add more insulation versus $12,500 to remove the old insulation, seal the house, and then re-add new insulation. With summer temperatures often hitting above 105°F, I'm looking to improve comfort inside my home, especially since winter is fine. I'm trying to decide whether to go for the insulation now or save up for sealing the attic first. Any advice? Thanks!
2 Answers
That $12,500 is for just sealing the attic floor, right? If so, that's a big expense just for air sealing. The main concern in summer is the radiant heat getting in, and topping off your insulation could help with that without excessive cost. It sounds like your current issue is more about heat transfer than air leakage, so spending $3,500 on more insulation might actually make a noticeable difference in comfort without breaking the bank!
I had a similar situation with my house from 1974. We added blown-in insulation to bump the R-value from about R20 and noticed a BIG difference in both summer and winter comfort. While air sealing is ideal, even just topping off insulation can help a lot. Just keep in mind that attic ventilation is also crucial since it affects how hot it gets up there, which can impact your whole house. If you're already well-vented, then doing the insulation might be the right call for now!

Thanks for the input! Thankfully, my attic is well-vented, so I think I’ll go ahead with adding more insulation.