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Stephen Tashiro
08-28-2009, 7:45 PM
I'd like to take off the old roof of my storage building in sections so I can work on it for a few hours during the shady parts of the day. To temporarily protect the exposed plywood sheeting from rain showers, I plan to put down sections from a roll of clear polyethylene. My first thought was to lay the poly down and put weights over it.

Then it occurred to me that I could simply staple the poly down nice and flat and then once the old roof is removed, I could put the tar paper over the poly and put the new rolled roofing on top of that. I would expect the poly to deteriorate. But would that do any harm? This is a flat roof so I don't think the fact the poly is slippery is a problem. Opinions?

Walter Plummer
08-29-2009, 5:50 PM
I would NOT leave it. Evan if it is just a shed I think it will trap condensation and cause rotting.

Michael Wetzel
08-29-2009, 6:43 PM
Tarpaper is a water barrier too and doesn't breath. So I am not sure if it would hurt.

EXCEPT - Plastic sheeting is a pain to walk on on a slight slope, what is it going to be like on a roof?

Stephen Tashiro
08-30-2009, 1:25 AM
A related question is whether it's ever a good idea to put down more than 1 layer of tar paper. My understanding is that tar paper is intended as a vapor barrier, not as a roofing material. So this would argue against the usefulness of putting down two layers. But does it have a bad effect?

David G Baker
08-30-2009, 9:27 AM
If the roof is small enough I would get a roll of ice shield and cover the whole roof. Not cheap but very efficient.
I would not use plastic sheeting for anything but a temporary protection from the elements. I do use plastic sheeting on ceilings prior to installing a ceiling if I plan on insulating the shop or garage attic.