Do I have to tear off my old shingles??

Hi All
I live in Long Island New York. I would like to replace my roof in the spring. There is Two layers of asphalt shingle on the house now, The roof is not in really bad shape. I would like to install the new style shingles that look like slate or cedar. Can I install these over my existing shingles??
Thanks John

 

Most codes won't allow a third layer of shingles so you'll need to find out what the local building department thinks.

You shouls also ask about the legality of real wood shake roofing. It can be serious fire hazard and lots of places won't allow it. Others allow only treated shakes.

 

Hey Dave
The shingles will be asphalt,They just look like cedar or slate.
I beleive the codes in my area allow for three layers of shingle.

 

Stirp both layers of old shingles off. Take a good look at your sub roofing and make sure it is in good shape. By taking off both layers, you will take alot of weight off your house. Your new dimensional shingles will be heavy. Do not put your house through this stress. Also, if you do not do a complete tear off, your new shingles will not lay flat, your ice and frost will not lay correctly, your gutter apron will not be correct, and most importantly, the warranty on your new shingles will be void. I will never do a roof over. I have passed up many jobs because of it, but I just like to do things correctly. Good Luck

 

Always tear off the old roofing when ever the budget allows. If you insist on placing a new roof over the existing check with your building dept to make sure. If you put a 3rd layer and it's not supposed to be there your going to have to tear it all off and install a whole new roof anyways.

A "tear off" usually lasts longer than a lay over because when tearing off youa re able to address any issue that the roof system has. I always encourage my customers to tear off their roof.

 

I would tear off for the reasons stated, plus.. 2 old layers of roofing could mean its been 40 years since the decking has been inspected. I personally hate layering a roof like that and would never do it.

 

You'd have to use 2 1/2" roofing nails just to get through allt he shingles and hit wood.

 

Hi
Thanks for everyones input, I always do things the correct way.
It looks like I will be stripping the old roof. I want to do this project myself to try to save money. I wanted to not strip the old roof so I could take my time and not worry about the weather while I went along. Could I strip one small section at a time and install new shingles in small sections instead of ripping the whole roof off and install new??
Thanks John

 

John,

I'm sure a lot of DIY re-roofs start in April and finish in June. There's a reason the pros cost what they do, it's a very labor intensive process with safety risks and little margin for error.

One option could be investing in a few tarps, tearing off part of the roof one day and reshingling the next. You'll probably find the bare decking a bit more comfortable to walk on than 2 layers of old shingles.

One disadvantage of doing it a piece at a time is you will either have an extended dumpster rental, or an ever-growing pile of old shingles in your yard. If you could tell us how many square (1 square = 100 square feet) your roof is, one of the experts could probably suggest how big of a dumpster you'd be looking at for all those old shingles and felt.

Oh, and if you are going to DIY this, please don't cut corners on materials. Ice & Water shield, drip edge, and valley flashing are your friends. And whenever you start to get near the top, I'd encourage you search "roof ventilation" or "attic ventiliation" on this forum.

Good luck. You'll probably lose 10 lbs. in the process.

 

If you've never done a roof before, I would suggest that you not try to do it in sections. That can be even more difficult than doing the whole roof. One issue you'll have to deal with is how you'll tarp between the new/old roof. You never want to drive nails into the new roof, so how will you fasten the tarp?

 

Good point, Dave. I was envisioning that he could fasten the tarp to the gutters at the bottom, since he has to start the roof at the bottom. He could keep it nailed at the ridge until he got there.

 

That might work but I always worry about wind. When I lived there in the late 70's, Long Island got some bodacious thunder boomers and even a couple of hurricanes.

 

I agree with all the points made on removing all of the old shingles at once. I just think it would be a real project getting the tarps on the whole house. My house is a L shaped one story ranch that has 3 hip style roofs. I just think since this is the first time I am taking on this type of project I can tear off one hip and shingle it in a day or two.This way I would just have to tarp a small gap between new shingles and old not torn off roof.I would nail the tarp to the gutters and the old roof. What do you think about this plan??? Thanks Again John

 

Dave, i remember tarping a roof on a friends house DURING a thunderstorm. We had just put all the trusses up and and put the cross braces in when a tstorm decided to showup. We were lucky and had the tarp on half the trusses, so we just had to pull it back over the rest. Ever try to tie a tarp to a roof from inside with 30+mph gusts hitting? That was an experience... you live and learn.

Moral of the story: only take the tarps off what you are currently working on and not everything.

For the DIY'ers if you are working with ice and water shield, read the directions carefully. I am not sure about all brands of it, but some of it degrades from UV exposure. So don't put huge amounts of it down and let it bake in the sun before you shingle over it. Or you could tarp it if need be..

 

Definitely tear it off.

 

Hellrazor -
I've never tarped a roof during a thunderboomer, but I once had to hustle around laying bundles of shingles on freshly laid roofing paper.

Pullnit -
Go for it if you feel you must. Hope it works for you. One other thing to remember about roofing is that there are two kinds of people who do roof work. Those who have fallen off and those who are going to.

 

Along with the other experienced roofers, I also say TEAR IT OFF! That's the only way you will be able to see if the sheathing is in good shape (and be able to repair it if necessary). It also gives you a good base for your new roof, and reduces the weight your home has to support (each layer of regular shingles weights 2-3 lbs per sq.ft., and the really thick ones go up to 6 lbs.).

As far as protecting the roof after tear-off, we use an underlayment called Triflex-30 (there are also other similar products) which is far superior to tar paper. We've had more than one thunderstorm go by with a roof covered in this manner without any wind damage or leakage.

As Dave has noted, working safely on a roof is not a simple matter, so you may want to consider a professional roofing company (properly bonded and insured). They usually can do the tear-off much quicker than you can, and have the specialized tools to let them do so.

 

Hey pgriz
I am not really worried about getting hurt on the roof. It is only one story and the pitches are not very steep. If I was to use a product like the triflex could it be exposed to rain for a week or two without damage to the material?
Thanks John

 

Yes, it would not hurt the Triflex. That stuff is tough. If you want you can e-mail me direct. Good Luck

 

As Jack has noted, the stuff is tough. I had one person put it up on a new construction in fall and got around to doing the roof next spring. He tells me that there was no damage even though he's in the snow belt. I wouldn't leave it uncovered that long, but it seems to survive weather pretty well. However, you need to be sure you have proper amounts of overlap (4 inches minimum) and ensure that all edges are well secured against wind uplift. Also, the material can be torn if you over-drive the nails and the nail-head cuts the material.

 

The triflex sounds like what I need. Can it be stapled or does it need to be nailed? Will I still need a Ice protection layer by the eaves or does the triflex replace it?
Thanks John

 

For proper holding strength, it should be nailed. In fact, if I was doing it, I would nail 1x2 furring strips along the rake (gable) to ensure that the wind would not lift the triflex. The furring strips distribute the wind load and reduce the chance of it being ripped. However, they will have to be taken off once you're actually covering the roof with shingles, or whatever product you will use.

Triflex is NOT a replacement for Ice-and-water shield membrane, and in all areas where you need that type of protection, you do need to install the membrane. In our own practice, we install I&W membrane in all the sensitive areas (eaves, valleys, along endwalls, etc.) and then cover the entire surface with Triflex. It's overkill, but I'd rather be safe than sorry.

As for getting your hands on it, it may be available from professional roofing supply sources near you, or maybe Jack has a suggestion. We sell it ourselves, but you can probably find a source closer to you.

 

Pgrz, how much they nail you for a roll of triflex? I have not noticed it anyplace i deal with local to me.

 

Hellrazor, we buy the product directly from the Flexia factory in Brantford, Ontario by the pallet, and pay volume pricing, so I don't really know what it would cost in your area. You can find their web site at www.flexia.ca and there is a contact page for you to find a distributor close to you.