You're dealing with a classic cottage problem where that tongue and groove looks great but offers zero thermal protection. Since you've got that lopsided insulation pile, the first thing you need to do is spread that back out and air seal the gaps. People overlook the bypasses where the wall meets the ceiling, but that's where your Mississippi humidity is creeping in. For the storage area, don't just lay down plywood; use some high-density XPS foam boards or build a raised platform so you don't compress your loose-fill. Compressed insulation loses its R-value immediately. Skip the attic fan entirely since it usually just sucks conditioned air out of your living space through the unsealed ceiling. Instead, focus on baffles and soffit vents to get a natural cross-breeze going above your insulation layer. If you want to go the extra mile, adding some rigid foam between those rafters helps, but your biggest win will always be at the floor level. It’s definitely possible to make an 800-square-foot place feel comfortable again without starting from scratch. Once you stop the heat transfer from the roof deck, those window units or your HVAC won't have to work nearly as hard to keep up.
How I finally solved attic temperature swings — steps that actually worked
Aug 19, 2026
Last reply: 6 hours ago
3 Replies
I went thru this exact process with my 1940s bungalow last summer. The air sealing made a bigger difference than the extra ten inches of blown-in cellulose I added later. I spent three days crawling around with cans of Great Stuff Gaps & Cracks, focusing specifically on where the top plates met the lath and plaster. Like you mentioned, those bypasses were huge; I coud feel the humid air pushing up from the kitchen.
For my storage area, I used the raised platform method with 2x6s perpendicular to the joists. I tried the XPS foam boards first, but I worried about long-term compression under my heavy seasonal bins. Building that deck took a weekend, but it allowed me to keep the full R-49 depth without squashing anything.
One thing I’ll add: watch out for the soffit vents if your house is as old as mine. My eaves were so narrow that the standard plastic baffles wouldn't fit right. I ended up cutting my own out of thin plywood to keep the airflow moving from the vents over the top of the insulation. Once I finished, my electric bill dropped by about $40 a month during the peak of August.
This is all news to me, expecially the part about air sealing before the insulation. I honestly thougt you just threw more pink stuff up there and called it a day. When you talk about those top plates and gaps, how do you even find them under the old dust? Also, if I build a raised platform like you did, do I need to worry about the extra weight on my old ceiling joists? I don't know much about structural stuff, so I'm scared of overloading it with heavy bins.
Have you ruled out existing moisture issues in the roof deck before sealing everthing up so tight? If you trap even a little dampness from a minor leak or high humidity under a new layer of cellulose or foam, you're basicly inviting rot into those old rafters. Also, are we sure the heat gain is actualy the ceiling? Sometimes people over-insulate the attic when the real problem is solar gain thru unshaded south-facing windows. Have you checked your glass temperatures during the peak of the day to see if that's where the load is coming from?
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