Hello, gentlemen! I’ve got a roof-over question, and I know they are highly frowned upon…but I’m hoping to get a bit of advice. I’ve recently re-roofed my house, and torn it all off. However, there wasn’t enough room in the roll-off for the garage. Luckily, the garage was built about 10 years ago, and only has one roof on it, which is in perfectly fine shape. I just want it to match the house. There are no leaks, and, other than faded color, the original shingles are in good shape.
However, I’ve noticed on the back side, a simple bump-and-run isn’t going to do the trick. The original roofer wasn’t really keen on straight lines: The shingle line sags in the middle. A lot. So much so that bump-and-run is out of the question.
Any suggestions (other than the obvious “tear it off”)? Fortunately, the front was pretty close. Just the back is horrible. I appreciate any advice (even if all I get is “tear it off”).
Snap some chaulk lines, or paper over it & snap lines on the paper.
I make my living solely off of repairing shingle roofs. When the hard rains come, I always get several calls concerning leaks on multiple layer roofs. Many times the leak is being caused by unlevelness due to roofing over another roof in some other manner than a butt and run. If you don’t butt and run, it will not be level and smooth like a roof needs to be. I know you might not want to hear it but “tear it off”. The roof will be up there 20 plus years. Why not take one day to get it right?
That’s really strange, today I just did my first roof over since 2010 and I probably wouldn’t be sharing it with the roofing.com crew if you didn’t ask this question lol. What’s the pitch of the roof? If its a 6/12 or steeper I think you should be fine just doing what bob suggested. Any flatter and I would be worried about the unevenness that chuck talked about if you don’t but and run it.
It’s between a 4/12 and 5/12. I figured that would be the answer, but a guy has to try, right? I’m, unfortunately, at the end of my budget. I don’t mind spending another day at it, and honestly, I tore off two layers on the house, so this would be the easiest I’ve had it. Just had too many cost over-runs in other areas. The extra underlayment and another roll-off are just not feasible. I know this sounds dumb, but would it be worthwhile to snap a line and take a hook blade to straighten out the tabs that are there to make the bump and run straight? That would cause some trash, but not as much as a full tear-off. I could probably fit it in my garbage container just fine.
I’m going to go out on a limb and guess that the unevenness would lead to early failure? I don’t mind if it looks somewhat ugly. Frankly, it’s the back of the garage.
Since you insist to not tear off the roof you can try this. Many years ago there were not just 2 ways to do a roof but 3. Tear off, roof over and what was called a de-tab job. Do the butt and run on everything but the back side and do the de-tab on it. Take a square head spade shovel and run it horizontally across the backside knocking the tabs ( or bottom half ) of the shingles off. This will prevent the unlevelness issue. You need to do this VERY early in the morning while the shingles are still cool. Then just pop lines and the roof will be level and straight when your finished.
I’m going to go out on a limb and guess that the unevenness would lead to early failure?
The unevenness on a 5/12 slope and less will cause the water to run down ( vertically ) to the uneven spots and then run ( horizontally ) because of the dam effect and leak into your garage.
How big is this garage? 8-10 squares or less? Tearing off a 1-layer roof is MUCH easier than two layers. Do you have a truck or a friend that would let you borrow one? You could tear off the roof and haul it to the landfill fairly cheap. If money is tight just put 15# felt on it. That would cost maybe 30-40 bucks or you could most likely just re-use the existing underlay if you tear it off with a spade shovel and are careful not to damage it. It’s only 10 years old right? If it would be a newer truck you can put a tarp in the back of it and leave the tarp draping over the sides, top, etc to ensure the truck doesn’t get scratched up.
Thanks, LC. I appreciate the advice! Had I known everything I’d run into here, I’d have sold a kidney or something and just paid someone else to deal with it. Luckily, if I do run into issues later, it’s the garage, not the house.
With all the issues I’ve had with this house, I can’t stress enough: When you buy a house, get a home inspector you trust. I’d like to have known even half the stuff that was wrong before pulling the trigger on this place.
Whoops, somehow I completely missed the second part of that post. That was a pretty good guess on size: It’s 9 square. I may be able to find a friend with a truck to get it gone. I may have enough Ice & Water to do one side, and felt is like $15/roll for 30 or 15. I really appreciate the advice!
[quote=“johnnyreece”]It’s between a 4/12 and 5/12. I figured that would be the answer, but a guy has to try, right? I’m, unfortunately, at the end of my budget. I don’t mind spending another day at it, and honestly, I tore off two layers on the house, so this would be the easiest I’ve had it. Just had too many cost over-runs in other areas. The extra underlayment and another roll-off are just not feasible. I know this sounds dumb, but would it be worthwhile to snap a line and take a hook blade to straighten out the tabs that are there to make the bump and run straight? That would cause some trash, but not as much as a full tear-off. I could probably fit it in my garbage container just fine.
I’m going to go out on a limb and guess that the unevenness would lead to early failure? I don’t mind if it looks somewhat ugly. Frankly, it’s the back of the garage.[/quote]
That’s not dumb at all, that’s what you do.
When you lay the shingles for the go-over make he stagger a little bit larger, 8"-10" and only use 4 nails per shingle making sure that the nails are at least 2" away from any seam.
You will get a better result by hand nailing, if you hand nail it use hot dipped galvanized nails or better.
Thanks for chiming in! I’ve got a couple boxes of hot galvanized nails. I think they may only be 1 1/4", though. I do have 1 3/4" nails for my coil nailer that I use on hip/ridge cap. I don’t mind hand nailing, as my gun is old and flakey. I end up finishing all the nails by hand, anyhow.
Johnny, that’s not a bad idea at all
As long as you can pop some straight lines in the right spots.
I think it seems feasible. It sags in the middle (not the decking, the line). Kinda looks like the shingles are smiling at me. An evil-looking grin…I’m at least hoping the sides are right, so that when I snap a line from one side to another, they line up in a not-crooked fashion. I’m not going to bet my life on it, though.
I think you should consult a good roofing contractor. He will help you in right direction.
I’d like to think the gentlemen here are offering pretty good advice. I do have an uncle who is a retired roofer that I consulted with when doing the house, but he didn’t do many roof-overs. I know that’s kind of a dirty word in the roofing biz, and I’ve also found contractors around here aren’t keen on giving advice on jobs that they won’t be working on (which I completely understand). I’m thankful for all the responses I’ve received here, and appreciate the time and thought that went into it!