Is it ok to put another layer of shingles on my roof?

there is already 2 layers on the roof now. I have had 2 contracters tell me it's ok and the extra weight will not matter. I'm considering a much heavier shingle than what's on there now. it's a ranch stlye home around 2000 square feet. house was built around 1965Is it ok to put another layer of shingles on my roof?
Hi, I'm a professional roofer, expert at it at least, getting close to mastery.





Different states have different building codes. Some states say three is the legal limit, others like Ohio where I'm from, say two layers and no more. Regardless of the legal mumbo-jumbo, there are a few things to consider first:





1) Is there possibly a wood problem underneath the current shingles?





2) Placing newer shingles over older ones often reduces the lifespan of the new.





3) How much cost difference is there between leaving the old and tearing it off?





4) Considering that cost difference, do you really want to leave the old, knowing that it will reduce the lifespan of the new? (so next time replacement comes 5-10 years sooner, if not more)





5) How good a quality are the old, and their condition? (are they going to continue to deteriorate, and reduce the life of the new even more?)





6) How good a quality will be the new? There are some brands of shingle out there that I wouldn't even put on a doghouse. These will not last over old. I have a friend right now who bought a house with 5-year-old shingles; he's had the house two years since, the shingles are SHOT. It had been stripped down to wood, all the old torn off. I won't mention the brand here on this site, but I'm told there is a class-action lawsuit against them right now. Cheap shingles from a ';good';, recognizable name brand.





Do your homework. You can email me if you wish and I'll tell you some decent brands to stick with and the one to avoid.





Also: PLEASE, PLEASE, PLEASE check out your roofer THOROUGHLY. I personally have had to fix many ';new roofs'; and ';repairs'; by individuals and companies that don't know their butt from a hole in ground. It is amazing how many contractors there are out there that are ';reputable companies'; and don't know what they are doing.





Probably the best thing to do is ask friends, neighbors, etc. who they personally would recommend -- ask many people. Only listen to their recommendation if they personally had that company do work -- no name-dropping. A lot of marketing flooding an area can make a single name stand out more, but you cut through all this by looking at their work. I wouldn't use lists by agencies that back so-and-so. It's too easy to get put onto a list, and few get taken off once they are on. There's a company here in Central Ohio that is popular with the public due to lots of advertising and size of the company, but if you asked a true professional in the field -- we wouldn't let them within eyesight of our roofs. So beware. Ask friends and neighbors who has done their work. Go with one or two companies whose names come up most often as having done excellent work.





If it were my house, I would strip it all down to wood and look at the wood, fix any wood properly, then build it back up. Make sure that a good underlayment is used (tar paper, ice guard, etc.). Some roofers won't use any, some use very thin. The thin stuff can be OK, but you have to take things like roof pitch, funky architecture (such as an area that might trap a lot of snow and ice), and various flashing issues, all taken into consideration.





Spend the extra money on a longer lifespan (40-50 years) shingles and a company that knows what it's doing. There isn't a lot of difference in the wholesale cost of better shingles, so if a contractor charges a huge amount more, find someone else. Also take into consideration the windspeed of storms (tornadoes, hurricanes, etc.) -- different shingles have different windspeed ratings. Some won't stand up to a good storm. In Florida for instance, lots of hurricanes have made that state very strict on what is passable for shingles. Malarky shingles (yes, I did say Malarky, a name brand) is one of the best for windspeed durability. Funny, isn't it? But they are not available everywhere, I can't even get them here in Ohio.





Hope this all helps, as I said, you can email me if you wish. I have my own company and various friends also with their own. Between all of us, I have access to over a hundred years worth of experience, close to two hundred between myself and all my friends, added up of course.





Oh -- a tip: if the contractor brings a camera and is willing to do up pictures for you of the roof and it's various issues, it says a lot about their honesty. Digital cameras are wonderful -- you can take a zillion pictures up there, burn them onto a CD and give it to a customer that can't or won't get up on the roof.Is it ok to put another layer of shingles on my roof?
If the roofers you talked to have a good reputation they would know better than I. I have heard about multiple layers of shingles being put on houses but I do not know how many layers is acceptable.
3 is the max
I recommend you strip off all of the shingles.Then you can inspect for bad plywood. Never put shingles over top of previous shingles.A newly roofed house should last from 25-40 years depending on the type of shingle installed.
I would not recomend any more then 2 layers I have seen some put on three but there subjuct to leaking and then you need to worry about yourf ply-wood under all this. and you say it was built in 1965 REPLACE THE SHINGLES AND CHEC THE PLY-WOOD
Normally only two layers are put on then the next time new shingles are needed the old ones are stripped off.
I am a home inspector. Each additional layer of shingles takes approx 5 yr off the life of the top layer. So, if you put on a 3rd, count on losing approx 8-10 yr off the normal life. The weight would depend on the size of rafters or trusses and if you get snow. The cost of removing the old is not so much compared to having a roof failure or losing 10 yr off the life. If you trust the roofer and they will guarantee the life and the damage, and will that company be around in 10-15 yrs to take care of you, then go for it. Also many insurance companies limit houses to 2 layers and will not cover if 3 layers are on house.
do you get snow load? is the sheeting OK? simply putting new on old is not always the best. have them pull a row near the eave down to the sheeting, that is where damage would most likely occur. if OK, go for it.
I would remove the old and then add the new, my personal preference. It will cost a little more to have someone remove the old and dispose of them. I do most of my own work on my house, so, It only cost me the price of new shingles and Roofing nails. But, I understand many people may have to hire this done. IF, you do then consider the Costs of both approaches, if you can justify removing the old, then I would. Good Luck.
I would'nt do it. tear off the shingles to the plywood then re-shingle. dont trust those contractors.
Do you trust the contractors? Are they licensed? I'd follow their advice then.





In the long run, it's better to replace rather than to cover.
that's good to have several opinions-professional ones. Apparently these contractors are saying these existing shingles must not be in bad shape that could cause these new ones any problems, weight wise etc. See what the price difference is and it may be in your best interest to go ahead and have these removed. Have you checked these people out like with the Better


Business Bureau? I'm just saying this because my Dad wound up one time having a job done and had to turn around and pay out more in the long run. It wasn't with shingles but it was with contractors. Good luck to you and enjoy your new roof to come!
It depends what state you're in. Sounds like it ok if the contractors are ok-ing it. I'd say if you haven't had any problems with the roof leaking, or pieces of the old roof coming off, then go ahead and put on a 3rd layer. But I don't know how long they'd be able to ';warranty'; the roof for..


But if there are any problems at all, strip the 2 layers off, inspect for problems in the wood, and then put on a new roof. Different shingles have different life spans. Anywhere from 10 to 40 years. This is the way I'd go. Too many problems with layers!
The problem is that the felt layer can go bad too. I think it is a general rule to just have 2 layers of roofing. With the 3rd roof, have the 1st and 2nd layers removed as well as the old felt paper. Then have an bad spots of wood on the roof bigger than a walnut removed and fixed, then new felt paper and then the best quality new roof you can afford. Most of the cost is in the labor so if you can afford to upgrade to lifetime shingles, you are better off instead of getting 15 year shingles.
It is absolutely not OK. I wont even put shingles over 1 layer. They need to be taken off, and the roof sheathing needs to be checked. If the sheathing is OK then shingle the roof. Make sure the attic is vented correctly. A poorly vented attic can take many years off the life of your shingles.