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You are here: Experts > Home/Garden > Home Improvement/Repair > Roofing > installing shingles according to manufacturer's specifications
Roofing - installing shingles according to manufacturer's specifications
Expert: Brad Zacharia - 10/31/2009
Question
QUESTION: My house was just re-roofed (tear-off)with Timberline high definition prestique 30 shingles, charcoal. I noticed we were not getting high definition affect so I measured many courses and found the shingle offset was not being closely adhered to required by manufacturers instructions for application. For example some shingles were off spec by 3or 4 inches and as much as 8 inches.
What are the consequences of not following manufacturers application instructions with these shingles. Besides appearance issues will leaks occur in the future. What are acceptable offset tolerances for these shingles. What recourse do I have. I believe the roof should be re-done-am refusing to pay balance due. Thanks
ANSWER: They can't be offset by 8" or the shingles would leak. You must be talking about something else. Timberline shingles are easy to do and cover a lot of mistakes.
Brad
---------- FOLLOW-UP ----------
QUESTION: Perhaps I'm not using right lingo--so here goes
what I mean is roofer did not follow application instructions layed out by Gaf--1st course-full shingle
2nd course trim 6 inches
3rd course trim 11 inches
4th course trim 17 inches
then repeat--roofer did not trim beginning shingle for each course according to these measurements instead trimmed without measuring and so there is no uniformity of pattern
Answer
Oh, those numbers. I have never seen any roof installed according to those numbers yet they do have them in the instructions. These numbers have two purposes. One is to make sure the pattern of the roof works out visually but on Timberline there is no pattern since the shingles are random patterns. The other is to make sure that the shingles have a side overlap sufficient to prevent leaks. In a standard roof you must have each shingle end at 6" sideways to a cutout below. On a Timberline roof you have infinite positions possible as long as the end of one shingle is not within 6" of a nail or seam below but most roofers still use the 6" pattern. If you have a steep slope you can use closer numbers. For instance, on a steep 3-tab shingle you can do a 4" pattern just to be different and then the rows repeat the pattern every 3 rows instead of every 2 rows.
But to sum, I do not know why GAF uses that numbering system and I know of no roofer that uses it. It could be to space out the seams so it is less visible. In Timberline it is hard to see the seams but if the roof is sloppy it might be visible and using the numbering system by GAF the seams would be all over the place instead of lined up and less noticeable.
Unless something else is wrong with the installation, not using those numbers do not cause leaks and no one uses those numbers.
Brad
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