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Insulation question... sort of. I started to post this in the quick questions thread, but it quickly got out of hand, size-wise. Apologies. I've got a late-fifties house on the central coast of California. I'm guessing that because of our mild climate of the time and the impending future of Cheap Atomic Energy (!), it was built with single-pane glass everywhere and no insulation anywhere. The house is also a cheap imitation of an Eichler: low pitch 1 in 12 roof where the inside ceiling follows the roofline. So, on the inside, I look up and see 2x6 T&G lumber running from the lowest part of the ceiling (7'6") to the center, highest part (9'6"), all supported by 4" wide beams (of various heights) that run the length of the house. It's a hot-mop roof so, on top of that T&G is (maybe) a fiberglass mat, plywood, felt, tar and gravel. No attic space whatsoever. Here's a ceiling shot from before I moved in:  On our warmer days (of which we have many), this house gets HOT. I'll see interior ceiling temps at 95-105 degF. Even after it cools off outside, the house remains uncomfortably hot, due the ceiling radiating the heat down into the living space. Our warm season has already started and with how miserable I was last year, I'm motivated now to start doing something about it. Options: In the SF Bay area, I see a few companies that offer a topside spray-foam treatment that completely seals and insulates the roof and they cover it with a white acrylic paint to keep the UV from breaking down the foam. Apparently this is a typical flat-roof way of doing things for industrial buildings in hotter climates, but I haven't found any companies in my locale that offer a service like this. If I could do this, I would... it's probably expensive, but probably the most effective. Besides ripping off the current roof and rebuilding with trusses and attic space (a neighbor two doors down has done this, poorly; it looks like rear end), I think my only other option is insulate from the inside. If I had more space on the inside, I'd just do a small drop ceiling job; run 2x4's on 16" centers parallel to the support beams, pack them with fiberglass batts and cover with drywall or maybe 1x6" t&g. In fact, I've just completed a bathroom remodel where I did exactly that. Because the bathroom was in the middle of the house and had plenty of ceiling headroom, I dropped it by 6" so that I could add can lights and a fan vent. However, in the perimeter rooms the ceiling gets progressively lower and there are some features which won't allow me to dedicate the full 3.5" of insulation. I've been considering using 2" rigid foam insulation instead of fiberglass. This Thermasheath 3 product is rated at R13 for 2", which is equivalent to 3.5" of fiberglass. That space saving comes at a cost, though... the rigid foam is $30 per 4'x8' sheet. Just over a buck per sqft; 2-4 times what the fiberglass costs. Another issue with the rigid foam, is that I'm envisioning a more complicated install than fiberglass. The batts are great because you snug fit them between studs and that blocks the air from leaking around them. The foam is going to leak around the edges a bit, no matter how hard I try to make straight cuts. So, to combat that, I plan to make the blocks a little under size and use spray foam to seal the edges... similar to what this guy is doing. My questions for the SA/DIY crowd: - Am I loving nuts? (More than normal, I mean) - Does this make any sense? I'm sure my sperging, detail-ridden description is a bit confusing, so I'll clarify in later posts as much as I can. But seriously, according to the limitations I've laid out above, does this solution make any sense? Am I missing a simpler/better option? - Will I end up on the Crappy Construction Tales thread? I have no plans to half-rear end this and I'm plenty confident in my abilities to make this all look nice. I'm not modifying anything that's load bearing and the weight of the drop ceiling plus insulation can't be more than 2-300 pounds per room. Still, I don't want to be one of THOSE owners who thinks they're clever. - Will this even work? Okay, I've answered my own question here with a couple experiments. Last year, I bought a few sheets of the Thermasheath, cut it to fit my spare guest room and just stuck it up to the ceiling with screws. Here's a shot of it going up:  Quick and dirty, I didn't tape or seal any edges. The difference was measurable. This was in July and we were getting 85-100 degF temps outside. I measure ceiling temps that were 8 degrees lower on the insulated ceiling, compared to a control room on the same side of the house. The room felt cooler, too, although the room thermometers only showed about 4 degrees difference. The other "experiment" is in my remodeled bathroom, It's got a full 3.5" of fiberglass, all covered with drywall for its new drop ceiling and it's a big difference as well. I see the same 8 degree ceiling temp difference (I was hoping for more) on our recent hot days, compared to the adjoining master bedroom. So yeah, I'm pretty sure that doing insulation everywhere else will have the effect I'm looking for. I'm even considering building in an air gap above the foam, just to cut down on conduction. I know, I'm trying to make this project as low profile as possible, but as you all know, thermal energy get transferred in three methods: radiation, convection and conduction. Convection is why I'm worried about sealing the edges of foam blocks. The Thermasheath is foil-lined on both sides, so if I give it an air gap between it and the original ceiling, that'll go a long way to cut conduction and radiation. Hopefully 1/2" gap is enough. Dear god, did I really write this big of a post?  ------------------------- TL;DR Is insulating my ceiling a decent idea?
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May 20, 2014 01:08
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His Divine Shadow posted:It's too bad you couldn't drop the roof down and get a flat roof all over. Eh... one of the few charms this house has is that it has high ceilings in the common areas. I'd hate to lose that. quote:Insulation is key though, you are right about that, keeps heat in, and out. Yup, okay... seeing that no one is yelling at me and calling me a moron, I think it's time to move forward with the plan.
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May 20, 2014 17:48
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Totally agree on the windows, although I've found that they make the most difference in our 'winters'. The first room that I'm going to start insulating already has proper double-pane window and sliding doors... I had them installed last year to see what effect they'd have during the summer... not much, unfortunately. I'll slowly be refitting the remaining glass as funds permit. The temperature swings you guys see are amazing... I'm easily in one of the most temperate places on the planet; below freezing? Maybe twice a year? I'd be so  except, somehow I'm still complaining. 
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May 21, 2014 16:27
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crocodile posted:i'm not going to be any help at all but i think you're nuts for even considering covering up that amazing ceiling Trust me, the ceiling was in pretty terrible shape when I got the place; it wasn't amazing but one of the worst aspects of the house. The original owners' must have been heavy smokers, as there was some terrible dark staining of the interior ceiling... the garage was noticeably lighting in color, but it was still pretty dark. It just made house feel really cramped and depressed... I researched maybe trying to have the wood sandblasted to bring back a more natural color, but time and money didn't really permit. The cheapest option was to paint it all white and I'm glad we did. Felt like the ceiling moved up 12 inches and brightened the place considerably.
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May 23, 2014 18:59
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cheap-imitation-of-an-eichler or not i always hate to see nice mid-century wood work painted or covered up. and i have a weird thing for wood beam ceilings.. anyway that being said i wouldn't be able to deal with the heat either and i'll be following this thread one: to learn more about insulation (i have a project coming up, too) and two: in the hopes that you can find a solution that doesn't require you to cover it up! good luck 