I’m bidding on a job where the architect requires that the bottom courses of the roof be removed, some repairs to the roof structure be made, and then re-install new shingles.
The problem is, that he is indicating that the existing shingles be left as is above the area of re-work. I don’t really like the idea of patching the new shingles in under the old – if these were asphalt, no problem – but it doesn’t seem right with cedar. The building is only a few years old.
Anybody have experience with this, can it be done well? Or should I ammend the bid and demand that the entire roof section be replaced?
Replies
can be done, but not always effectively. The extra labour to do a patch job as opposed to the whole section can penalize you to where the only extra cost is more materials.
I would only take it with a clause allowing ME to determine whether to take all or part upon seeing conditions at time of demo. You can bet the archy won't be the one standing behind the warrantee.
variables that would affect my decision are type of sheathing and condition - what kind of underlayment and breather space, the quality of the existing shingles, and how they were nailed.
Also, the pitch of roof, and style/shape/size of that section.
For instance, on a 4/12 with two valleys and a run of only 10-12 feet tot he ridge, I would not hesitate to take it all up, but on a 12/12 with a longer run or on a gable without valleys, I might be fine slipping things in.
But the labour to feather and patch can be three times as much per square as tear off and new for a small area.
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as Piffin says and if it is stapled like much shingle work these days you stand an even smaller / more frustrating chance of making a real mend
How do you fasten that last course of new shingles that slip under the old?
as you are sliding it into place, stop short of the chalk line about 1/4".Immediately at the bottom of the shigle butt left above this course, place your nails angling up. I usually use a nail set to snug them here.Then tap the bottom of the shingle to drive it up that last 1/4" to the line. The nails bend up so the heads are hidden just under the top shingle.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
We just had to do that on all the eaves of a hip-roofed house. Roofed two years ago, then owners decided to redo all the fascias and other trim. Not fun! But possible.
I just met on site with my partner and we were debating the technique of the angled nails. I wonder if that causes the nails to become a little loose inside the new shingle, and if they will be less secure in the long run. We were wondering if PL premium under that course would be better than nails. Basically laminate them to the next lower course.
It's all in the angle of the nail. Less than 45° and they don't go in tight. Closer to 60° and set the nail head just a bit as Piffin described, and they are tight.
A little PL Premium now and then never hurt anyone either. Just a dab, though--you want the shingles to be able to expand and contract with moisture swings.
The technique is called "blind nailing," by the way.