Roof Shingling – Remove Existing Shingles or Add Second Layer
jimmiem
| Posted in Construction Techniques on
The shingles on my house are looking kind of tired and will need to be replaced soon. The roof has a 3 foot strip of ice and water barrier along the edges and also has asphalt paper. I’m trying to decide whether to have the shingles removed before putting on new shingles or just add a new layer on top of the existing shingles. The existing shingles aren’t wavy or cupping but have some algae in spots. I read that adding a second layer of shingles can shorten their life. Also, any shingle brand recommendations would be appreciated……I live in New England.
Replies
In general, you lose money by shingling over. Obviously, if the existing have any unevenness you should not shingle over, but between the reduced life and the fact that it will cost twice as much in labor and disposal to remove two layers next time, it simply doesn't make sense (unless you're trying to fix up the house and unload it quickly).
Shingles
Thank You for your reply. Based on my age a good shingle will outlive me. But, if I just go for a second layer which shortens the life of the shingles then I just might outlive them in which case the next job would be, as you point out, more money. I guess what I really need to know is the life expectany of today's shingles as a single layer vs as a second layer.
My guess, 15 years. This house had a new roof over when I bought it in 1984 and 16 years later the roof was shot, patched twice and past end of life.
I am not sure the labor to take off 2 layers was really twice one layer but the disposal fee was.
The one place where a shingle-over saves a bit is with the valleys and flashing. In most cases that doesn't need to be redone. But there are cases where the extra thickness will cause problems for flashing -- hold water against step flashing, eg -- so that's not necessarily a good trade-off.
I would absolutely never do a shingle-over.
As you know, it shortens the life of the shingles. I don't know any hard and fast numbers for how much. Off the top of my head I'd say maybe 1/3. But that's just a guess.
I also think it makes the edge of the roof look terrible with the adeded thickness.
The fact that the roof might outlive you is irrelevant and short sighted. I take pride in what I do, and don't want to leave a half-baked job for someone else to deal with down the road.
Shingle-over
I admire you integrity and philosophy. The world would be a better place if more people subscribed to it. I wanted to offer you the shingling job and checked your profile to see if you are in my area (New England) and I noticed that today is your birthday. HAPPY BIRTHDAY!!!!
Shingle over
Duplicate comment.