Originally Posted by
Jerome W. Young
24 in = 10 in. exposure according to what i have researched
18in= 7in exposure
Depends on the wood species.
From the 2004 FBC-Residential, Table R905.8.6
Shakes of naturally durable wood - 24" length, No. 1 grade = 10" exposure
Shakes of naturally durable wood - 24" length, No. 1 grade = 7-1/2" exposure for 3/8" hand split shakes
Preservative-treated taper sawn shakes of SYP - 24" length, No. 1 grade = 10" exposure
Preservative-treated taper sawn shakes of SYP - 24" length, No. 2 grade = 7-1/2" exposure
Taper-sawn shakes of naturally durable wood - 24" length, No. 1 grade = 10" exposure
Taper-sawn shakes of naturally durable wood - 24" length, No. 2 grade = 7-1/2" exposure
Wood shingles are another matter, with 24" shingles having an allowed exposure between 5" (No. 3 grade) to 5-1/2" (No. 2 grade) to 5-3/4" (No. 1 grade) on 3/12 to >4/12 slopes, and an allowed exposure between 5-1/2" (No. 3 grade) to 6-1/2" (No. 2 grade) to 7-1/2" (No. 1 grade) on 4/12 and greater slopes.
Originally Posted by
Raymond Wand
The species and type of wood and thickness composing the shake roof will also factor in as to exposure. Is this shake or simply wood shingles?
Correct - see above table.
The fact the wood shingles are laid on plywood decking will shorten the life in half.
In Florida, most of Florida requires solid sheathing, structural panel sheathing, for sufficient strength to resist the wind loading from those high wind events Florida gets.
Not sure if it reduces the life of them or not.
Originally Posted by
David Banks
I would think the sun in Florida would shorten the life in half? Maybe down to one quarter.
Maybe even less than 1/4. The sun really kills them in South Florida. Jerome is just north of the north end of what is considered 'South Florida', the sun is not as brutal there, but I would still imagine a greatly reduced life expectancy, maybe reduced by half.
Wood shingles and shakes are definitely NOT the best choice for roofing material in Florida, especially in the southern half of the state, and critically so in the lower 1/4 of the state. Florida spans from Tropical to Temperate zones with the lower Keys being in the Tropical Zone, South Florida being in the Sub-Tropical zone, North Florida being in the Temperate Zone, and Central Florida spanning the vague change over from Sub-Tropical to Temperate.
Wood shingles and shakes may do well in North Florida, they do very poorly in South Florida, and mixed results between the two - Jerome inspects around where the north end of South Florida and the south end of Central Florida meet.
Back to the drip edge, or lack thereof ...
Unless it is stated in the manufacturer's installation instructions, I don't see it in the code, however, those manufacturer's installation instructions would need to be approved for the wind speed zone you are in, which would 'most likely be' either 130 mph or 140 mph. I'm not sure that wood shingles or shakes are rated and approved for those wind speeds. You would need to check the product approvals on them.
Nothing is easy in Florida, is it?