I'm not against foam. It's just not cost effective to bring it up to the code R value here in a ceiling, but I'd still skin the lid and blow the rest in. I live in Minnesota-when you can have a delta T of 110° in the winter, the insulation requirements get rather large.
Mike,
I sprayed 2" on my roof and 1.5" on the walls. My envelope is 40x70x10 with a 3/12 pitch. Cost me $11,500. Best money spent on the shop, hands down. I had a friend over on a day when the outside temp was 100 and had him climb a ladder and put his hand on the roof. His jaw hit the floor 14' below. The radiant heat barrier is insane. The only problem I had with my was where it caused the tin to expand just enough at a window to allow water to creep in on the J-trim channel, but I easily fixed that.
Once I get a cyclone and stop blowing my dust outside, I'll add 3 mini-splits to cool the place and control the humidity.
-Lud
According to the pump numbers he sprayed on average almost 4" across my gable ends and ceiling. $9500 is what cost me as we contracted for 3" in the 40x64 4:12 ceiling and gable ends. Ill prob regret not doing walls too but those batts are in. They finished at noon yesterday. It was 91 out today and the shop was cool inside.
Glad its my shop I am responsible for - I only have to make me happy.
Mike, it's not uncommon to "get more" than you contracted for when it comes to closed cell spray foam. You're paying for the minimum, but it's not an exact process for the operator who's coating your walls or roof underside. I paid for R38 "upstairs" in our addition and in most places they nearly filled the 12" joist bays 3/4 of the way...which is in many places about an R60.
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The most expensive tool is the one you buy "cheaply" and often...
Kinda glad of that then as some have pointed out R20 minimum in this temp band here
Glad its my shop I am responsible for - I only have to make me happy.