harry wrote:
On Jun 8, 10:28�pm, frank1492 wrote:
In small buildings (such as a shed) what is the downside to covering
the entire roof with aluminum flashing before shingling? Perhaps
expensive? That's the only thing I can think of.
� � �Any other negatives?
� � �I want to protect the wood indefinitely.
� � Thanks.
� � � � �Frank �

To preseve wood the imporant thing is to prevent condensation by
allowing ventilation around the wood. You need to allow through
ventilation. Eves to ridge or side to side. Metal roofing is very
prone to condensation problems.

I've read that without felt, shingles can also hold moisture in the
wood. Felt lets water vapor escape.

I've read that felt seals around nails. Someday as an experiment, I'd
like to cover a small roof with felt, nailing scraps of shingle on top
of it as battens. Rain would get under the pieces of shingle. After a
rainy spell, I'd remove everything and see if water had gotten to the wood.