On Mon, 23 Jun 2008 10:31:10 -0500, dpb wrote:

While weight can be a consdieration, the primary proscription on the
third layer is it tends to shorten life of the new shingles from
additional heat and poor conditions underneath.

Also, when it it time for a new roof, the roofers will charge a lot more
for the tear off and haul away of a three layer roof.

--
Tony Sivori
Due to spam, I'm now filtering all Google Groups posters.