IXLR8
Veteran Member
I was referring to a standard 16"OC wall.
Spray Foam Insulation
- Thread starter jgedmond
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I was referring to a standard 16"OC wall.
Please pardon my thread hijack, but I have a question related to closed cell foam and air conditioning [ cooling ]. I completely understand the heat saving feature, but is the reverse effect the same ? If a barn space is foamed, will I be able to maintain a cool space benefit ? And would the required thickness be the same?
So, if it's 0F degrees outside on a cloudy day in Winter and I want to have it 65F degrees in my work area from an XXXX Btu heat source [ a delta Temperature of 65F ], I foam to get the required R [if I'm saying that correctly]. So then in Summer and it's 130F up on the roof from the air and sun load, and I want it 65F in the shop (that's also a delta T of 65F) is the insulation value the same, so the cooling Btu A/C capacity is the same? I'd guess the surface temp of the roof is actually higher because of the sun load, so do I need a higher R or more BTU ?
Thanks.
So, if it's 0F degrees outside on a cloudy day in Winter and I want to have it 65F degrees in my work area from an XXXX Btu heat source [ a delta Temperature of 65F ], I foam to get the required R [if I'm saying that correctly]. So then in Summer and it's 130F up on the roof from the air and sun load, and I want it 65F in the shop (that's also a delta T of 65F) is the insulation value the same, so the cooling Btu A/C capacity is the same? I'd guess the surface temp of the roof is actually higher because of the sun load, so do I need a higher R or more BTU ?
Thanks.
3Ts
Elite Member
It's the same whether it's heating or cooling. The R value measures the materials resistance to heat transfer. I'm unaware of any material that is different based on which way the heat is moving. However, like you mention, in the summer time the roof is most likely hotter so the thermal gradient is more than 65*.
ovrszd
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And as Eddie mentioned earlier you need a "guide" so you can keep track of the depth you are adding.
I used spray paint. I cut off a lathe 3" longer than the depth of insulation that I was adding. Periodically stood the lathe up against a truss brace or whatever and shot paint across the upper end of the lathe. When we started blowing we had purple paint marks scattered around in the attic. I filled until I was near the mark and moved to the next area. Left my paint marks exposed so I wouldn't overfill and waste insulation in spots.
Used the same method when we did my Son's shop addition recently. Takes out the guess work.
EddieWalker
Epic Contributor
My shop isn't insulated and it can become unbearable in the summer. When I built my parents house, they wanted their garage to be fully insulated. They lived in the Sierra Nevada Mountains before moving to Texas and their garage there was insulated, so they wanted that again. I've never done or seen a garage insulated like a house, with R60 in the attick, R13 fiberglass in the walls, double pane windows taped for an air tight seal and insulated garage doors. No matter how hot it gets outside, it's always nice in there. My next shop will be fully insulated, the difference is significant.
How you insulate is up to you, the main goal is to make the walls air tight and the roof R value as high as you can get it. R60 is currently thought of as the point where you are maxed out and wasting material if you add any more. Walls are not as critical as the ceiling is because heat rises and cool falls. You just HAVE to stop the wind on the walls and then it doesn't take much to insulate the walls.
How you insulate is up to you, the main goal is to make the walls air tight and the roof R value as high as you can get it. R60 is currently thought of as the point where you are maxed out and wasting material if you add any more. Walls are not as critical as the ceiling is because heat rises and cool falls. You just HAVE to stop the wind on the walls and then it doesn't take much to insulate the walls.
ovrszd
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And it seems the AC mode struggles harder than the heat mode. Not because of R value necessarily but maybe the mechanical process?? For example, if it's 105F outside and you are wanting 65F inside the system will work very hard to do that (40F variance). Versus 25F outside and you are wanting 65F inside the system easily accomplishes that (40F variance).
Maybe someone can explain that or correct my misguided assumptions?
ovrszd
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Our 18x30 attached garage is insulated just like our house. Heated with hydronic floor heat. No AC. Two walls are shared house walls, they are insulated just like the exterior walls of the structure. It doesn't get unbearably hot in the garage in Summer. Easily heated in Winter.
The cheapest thing you can do to any structure that you expect to use year round is stop airflow and insulate.
My favorite saying is, "It doesn't matter what you heat a properly insulated building with, and, it doesn't matter what you heat an improperly insulated building with."
goeduck
Super Member
What is the best way to insulate skylight columns in the attic? Would this be a good closed cell spray application?
EddieWalker
Epic Contributor
Skylights are like holes in the bottom of a ship. You cannot do anything with them until they leak, then the best thing is to throw them away and put on a new roof.
