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Discussion Starter · #1 ·
I'm converting a 12'x20' (interior) shed, with 9' foot ceilings into a workshop. This shed came with the house. I'm leaving the ceiling open for storage space, but want to insulate the roof to deal with the cold winters and hot summers. I live in the Rockies at 4400 feet above sea level. There is currently a 12'' turbine vent on the west slope of the roof. I originally intended to just insulate the roof and sheetrock it and call it done. But realized that in doing so there wouldn't be any ventilation for the rest of the roof. Because the truss' are made of 2x4, using faced R13 insulation there really isn't any space for proper ventilation that I can think of. I plan to cut in two windows in the spring, and a third "window" for an AC unit. It'll have an 5000w electric garage heater installed this week. I've already insulated the walls and roof with faced R13. The walls will be covered with 1/2 ply and the roof with sheetrock. There isn't any other form of ventilation besides the turbine. If I didn't need the storage space, this would be an easy fix. I just don't know what is best for the roof in this situation. Just wanting to make sure that I don't create a bigger problem for myself down the road.
Any tips or advice would be greatly appreciated.
 

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It's all done so unless you're ready to remove roof insulation, there's not much to say. Insulation will slow the heat gain/loss, so it depends on how much cooling/heating you are going to do. So how much utility bills you are going to pay. Besides the bills, there's moisture problem. A vapor drive, sun's heat pushes the outside vapor into the roof/walls. Vapor will condense once cooled by inside air/AC. I would have left 2x space for air gap/dry space and added the insulation outside the rafters. Added rafter ties to create some space along the peak that can be exhausted to outside.
 

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Discussion Starter · #3 ·
It's all done so unless you're ready to remove roof insulation, there's not much to say. Insulation will slow the heat gain/loss, so it depends on how much cooling/heating you are going to do. So how much utility bills you are going to pay. Besides the bills, there's moisture problem. A vapor drive, sun's heat pushes the outside vapor into the roof/walls. Vapor will condense once cooled by inside air/AC. I would have left 2x space for air gap/dry space and added the insulation outside the rafters. Added rafter ties to create some space along the peak that can be exhausted to outside.
I just insulated it last week. The roof is just friction fit. Easily adjusted. My thoughts were to add 2 inches to all the truss’s giving me more space, keeping the R13 and adding a ridge vent. Not sure if there is an easier way or not.
 

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You're sacrificing the air/dry out space for few inches of storage. Fibers get wet and in contact with roof deck, so less air to circulate and slower dry out, maybe too slow, moisture stays all the time and that allows mold to grow, possibly start rots on the roof deck. Fiberglass insulation works by maintaining the air pockets in the fibers. Moisture in the fibers decreases the r value. These are proven events though your reality may be different. If yours stays fine, more power to you.:)
 
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