On 28 Jul 2004 09:56:40 -0700, (LD) wrote:

The roof of our 2000 sq. ft. bungalow (straightforward gable, 4/12
slope, no skylights) needs to be redone.

We've asked 5 contractors to give us an estimate. 4 are in the same
ballpark (i.e. $9,000 CDN), one is asking for TWICE that amount. He
says that the roof "felt soft" when he walked on it, so he's added
4700 sq. ft. worth of 1/2" plywood (to put on top of the existing one)
to his estimate. No other roofer mentioned "softness", but they did
indicate that, should they discover rotten wood underneath the
shingles, they would then charge us for the replacement (at $2.00 per
sq. ft.).

I don't have any experience with Canadian roofing, but in Texas we
have never had to replace an entire roofing deck in 11 years. If, by
chance, you have 3/8" decking, that always feels soft, but doesn't
mean that it should be replaced.

Normal procedure for us is to replace rotten decking using only the
amount required to cover the effected area safely. We don't patch a
small area with a whole sheet of plywood, we only use what is
necessary.

Well, I don't like surprises. Nor do I want to replace wood that
could still be in good condition.

Is there a way that I can assess the condition of the wood under the
shingles WITHOUT removing them? What signs should I be looking for in
the attic?

If you don't have any leaks, you won't have any bad decking. When the
roof is torn off the roofers will be able to see if there are any
problems that you are not aware of.

Also, is there a magic formula to calculate the size of a roof? None
of the roofers have quoted us the same size.

This is fairly common to get different sizes from different roofers.
Some measure from the top, some from the bottom, some just look at it
and take a guess.

The easiest way I've found is to measure from the ground, divide the
drawing into rectangles, calculate the dimensions, multiply the
dimensions by the appropriate number for the slope of the roof (in
your case a 4:12 should be multiplied by 1.06), and add on another
10-15% for cutting and waste, plus starter and hip & ridge shingles.

Since the roofers are quoting a price for the entire package, the
number of squares doesn't matter. Just make sure you hire a qualified
roofer, preferably one who is certified by a major shingle
manufacturers.


A.&B. Construction
www.1-866-Roof-Men.com