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TOPIC: Underlayment

Tempory (2-5yrs) metal roof. no decking

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I started building a home and ran out of money. I have a cement block basement, the front and most of the sides are exposed from the ground. I have premanufactured floor joists laid down with plywood over them. I cant afford to do the rest of the home so i ordered roof truss 4ft on center with 4/12 pitch. I laid some felt down, then started putting tin down, my neighbor says i cant do it that way i must lay down some osb/plywood then the felt, then tin. Can my way work? I also thought about lining the back side with plastic or the 4x8 sheets of foam that have foil on each side.
shawn lafferty

5/11/2010
You will want to put down something. If you put it directly over the trusses, it will not have any horizontal bracing, which is neccessary for vertical metal roofing panels. Just putting down plastic or foam will not give you this bracing. You can either use plywood they felt, or you can simply put down 1x4's then the panels. On a home, I generally reccomend the plywood and felt, but if it's a temporary roof, the 1x4s will work fine. Hope this answers your question.
Nate Libbey

5/13/2010
sorry i didn't mention this, but the truss' are all connected with 2x4's every 24"s, i belive they are called purlns? the tin is connected to them not the truss' themselves.
Guest User

5/13/2010
This should work fine, especially for a 2-5 year roof. When you get to the point that you will be finishing your home, I would recommend you put solid decking on that roof.
Nate Libbey

5/13/2010
a few people have been telling me that there will be to much condinsation in the roof.. And when i do the whole house it will have decking under the tin or shingles.
Guest User

5/13/2010
If a thicker gauge of metal is used (24?) would attaching the metal to the purlins without decking be structural?
Guest User

5/14/2010
Slafferty: There will be more condensation, but under a 2-5 year roof, it shouldn't be too much of an issue. The main causes of condensation are: - Not enough ventilation to allow water to evaporate and leave Solution----(Make sure you have air intake such as that at eaves or gable ends, as well as air ventilation such as ridge venting or turbines, etc.. preferably ridge venting) - Not enough insulation, causing the temperature outside to clash with the temperature inside, building up condensation. Solution----(Make sure you have adequate insulation in your attic.) Condensation is a tricky issue, with different buildings in different climates, etc... Main point being, if you're replacing the entire roof in 2-5 years, I don't feel that by that time it would cause enough of an issue to warrant putting plywood down over the entire roof - although it definately wouldn't hurt.
Nate Libbey

5/14/2010
Patrick: Even over 24 gauge panels, I still recommend either lathing boards (1x4s or 2x4s) running horizontally, or else plywood.
Nate Libbey

5/14/2010
+1 on Nate's recommendations. Eric Novotny
Eric Novotny
An informed customer is the Best Customer!

5/14/2010