2nd layer of shingles or tear-off/re-roof

[ArkTinkerer]

Title pretty much says it all. Roof is getting old but no major issues. Want to add a ridge vent if that matters. Debating just applying another set of shingles as opposed to doing a full tear off. I've seen houses with three layers and don't think I'd go that far but two layers doesn't seem to be a problem. Anyone do a second layer and run into problems? Does the second layer add insulation worth mentioning?

ArkTinkerer

 

[little jimmy]

I have always taken the old ones off. It is just my prefference. Lots of people do two layers and dont have a problem. Heck one rental had wood and then three layers of asphalt on it. As for insulation, I would say that there cant be much if any value to think about. If the old ones are rolling up then it will be hard to keep the new laying flat. Good luck either way.

 

[Toolman12]

I have put many shingle roofs down before with my father and IMHO if the existing shingles are not rolled up or missing then go ahead and go over top. if they are rolled then just cut the tabs off it's a lot less waste to have to haul away. Use longer nails and wait for a few of good hot days to put them on so they seal fast and strong. the advantage of complete tear off is seeing if there is any damage to the roof itself a company will always want to do this because it adds to there bottom line. So if no leaks and no rot then save a lot of time, money and mess and just go over top IMHO

 

[Norcal]

Remove the old ones, overlay roofs are a poor practice. Stripping the roof also makes possible for the sheathing to be repaired if needed.

 

[Big Poppa]

dont do a second layer of shingles unless that is all you can afford.... always better to strip it down to the boards....

 

[79firebird]

I my self perfer to tare off and not do a second layer depending on how the roof truss's are due to all that added weight.

 

[NUTTSGT]

I've often heard that if the current shingles are in decent shape, you can put a second layer on them. It makes me wonder to myself, if the shingles are in that good of shape, why are you putting new ones on?

Just my 2¢, I'd tear off the old.

 

[bob15]

Strip it. It's a no brainer.

Not sure where you live, but consider the weight of a second coarse of shingles, plus potential snow loads. Sure it might seem petty, but if you're in the North and get a record year of snow, collapses can and will happen. Your house will be happy without the extra weight.

Plus, by stripping it, you can lay down water & ice which will help prevent water damage should you have ice dams on the gutters. Also gives you a good chance to see how your plywood or tongue and groove roof boards are doing.


bob

 

[signcrafter]

Tear it off, no question here.

You will NEVER get as good of a seal going over the top of another layer. Roofing materials are like a puzzle with the ice dam, tar paper, valleys, flashing, etc. Tear it off so you can see any issues there may be that you can't see right now. Then start fresh. You will have piece of mind that you did the job right. With the wood in good shape start putting the pieces together. The roof will seal better and lay flatter. Think about it this way, when you put new shingles down you put them down on a flat wood roof with flat tar paper/ice dam on it. If you put a second roof on you are putting it on shingles that aren't really flat, they have spaces and also years of deterioration from the weather, even if they look in decent shape.

I've helped a few friends in the past do a second layer but I would never do it on my own home. The little bit of work it takes and cost to haul away it's just not worth it.

Now the one time that I might consider it is if I found cedar shakes under the original layer! I've done a few roofs that had two layers of shingles and cedar shakes and those ****. Take forever to tear off and then have to re sheet the roof. Not fun and in that instance I might consider just putting a second layer on!

 

[jeep450]

As long as you have regular 3 tab shingles. If you have architectural shingles you have to tear off because the weight will be too much.

 

[Falcon67]

Well - if you have, say you have 20 square up there of regular 3 tab. That's about right for a 1600~1700 box sq/ft with a 6/12 pitch. You'd double the weight from around 4500 lbs of shingles to 9000 lbs of shingles. Then next time, you HAVE to take them off. Think about the amount of extra work, the size of the dumpster to get rid of them, etc.

 

[nkachur]

This is an issue you will never have an agreement on. In my opinion strip the roof, it will allow:
- you to repair any sheathing damage
- reduce the weight load on the truss / rafter system
- get a better lay

the only advantages to putting a second layer on are:
- less work
- no disposal fees

If you can afford to upgrade metal is a better product than asphalt for your replacement.

Just my 2 cents.

 

[Gary S]

I've done it both ways. The second layer adds weight, but if your roof is structurally sound, it isn't an issue. I live where we get very heavy loads of snow some winters, and have never seen a residential wood frame house fail to handle the snow load with two layers of shingles. I see failures on commercial buildings designed by architects and engineers, but not on wood frame houses.

So, it is your choice.

 

[joshmodelskidoo]

if theres no damage and the shingles are still ok, the drip edge is good and no leaks i would just slap on another layer. i have herd of people even doing a 3rd layer buy i wouldn do that. depending on how steep your roof is you might want to put on some ice berior also. i have to redo my roof with a single layer on a double wide with rotted wood under the shingles on the overhang so its all getting torn off and iinsulation while im at it. you can always call up some roofers and see what there opinion would be

 

[Stuart in MN]

I think most building codes will allow two layers of shingles, and if the first layer and roof deck are still in good shape you can probably get away with it, but I think you'll be better off stripping the old shingles - that way you can be sure there are no hidden problems.

 

[Boomer343]

Check the warranty on your new shingles....most require certain underlays and if installed over existing shingles the warranty may be void.

Personally I'd strip and cover the decking with the ice shield....especially if skylights or valleys are involved.

 

[Rod N]

I left mine on and did a metal roof on top for $2 sq/ft.

 

[coolreed]

Take the old tiles off.

 

[dirttracker18]

I've often heard that if the current shingles are in decent shape, you can put a second layer on them. It makes me wonder to myself, if the shingles are in that good of shape, why are you putting new ones on?

Just my 2¢, I'd tear off the old.

This ^^^^^^

Lots of guys go two layers, good guys never do. It is poor practise to layer them. Do it right the first time.

I will also second metal roofing. Easier to instal, lifetime warranty, and looks and performs great.

 

[SuitorsGarage]

Do it right the first time and strip the old shingles off.
Only a fly by night or hack roofer would do a second layer in my opinion. I worked for a commercial roofing company for 11 years. We didn't do new construction, only re-roofs. We did not specialize in shingles but did plenty of them. Our idea of a shingle job was 100 or so condo/town homes in one shot remove, repair, replace. Never would we do an on over shingle job.
Now I am a self employed contractor. I will do roofs. I always insist on tearing off the old. I don't do it to get the price of the job higher. I do it for the quality of the work. I've ripped my share of roofs with shingles being the easiest to rip and really I could care less if I ever rip another one. Putting a second layer on is taking the easy way out. I won't do it that way if I do a roof. When I'm done with a roof I give a 2yr warranty myself. How do you know what the condition of the deck really is unless you see it for yourself.

Above all think safety! I know it is not an easy thing to do at home sometimes but you can get just as hurt on your own roof as roofing for a living.

 

[GirlnAgarage]

Strip the old.

 

[oldgoat]

For the most part I would strip it down for many of the same reasons mentioned like weight and check condition of underlay. I would also say though that if you go to a class 4 shingle with some insurance companies you can get a healthy discount on your homeowners insurance. Yes a metal roof is good, but I know on the old metal roofs that it could get noisey during heavy rain or hail. Also I saw on one policy that you would need to sign a waiver on the appearance of the metal roof for a discount.

 

[ArkTinkerer]

I've read a lot of opinions on other sites about this but very little to back it up. There are a number of caveats to doing an overlay--shingles can't be curling (mine are not), new shingles need to have the same exposure to lay correctly (can do), and the decking must be in good shape.

I read thru several warantees and there is nothing there that says overlays void the warantee. That said, the warantees on these products stink (prorated) and labor is the big thing.

The concept of inspecting the decking is the only valid issue I have seen. I have been up in the attic and seen the underside as well as walked the roof and all seems solid. I am trying to get this done before I have any issues. My existing shingles are not leaking but some spots have little to no mineral left on them. The ridges are cracking. It could last another couple years but that would risk problems. I'd rather fix it now.

Big savings for the overlay is labor if I do it myself. Also I can go slower--one section at a time--and it would be easier to follow existing courses. Current roof has no drip edges installed, I can order drip edges intended for overlays and actually have a better roof. Biggest concern for me is doing the valleys--I don't like the way the old ones were done -- they just don't look like water would flow right over them.

ArkTinkerer

 

[5lima30]

Tear off!

 

[NUTTSGT]

Big savings for the overlay is labor if I do it myself. Also I can go slower--one section at a time--and it would be easier to follow existing courses. Current roof has no drip edges installed, I can order drip edges intended for overlays and actually have a better roof. Biggest concern for me is doing the valleys--I don't like the way the old ones were done -- they just don't look like water would flow right over them.

ArkTinkerer

If you're worried about the valleys, I believe that is more than enough reason to tear off the old. You may want to inspect to see if there is any damage under the shingles/valley material.

 

[BD1]

DEFINITELY tear off. That's a lot of weight. Figure how much the new shingles weigh and you will remove old. Don't know your location but if snow load is a concern, tear off.

 

[KnurledNut]

1. Does the roof sag right now? (From ridge to eave?) Tear off.

2. If you can get it the attic, see how its framed...
then throw a couple numbers in this calculator:
http://www.awc.org/calculators/span/calc/timbercalcstyle.asp
If its inadequate, tear off.

3. If its structurally sound, and you got three tab, you could overlay.
Use a 5" starter course, and a 10" first course to get you running right.

4. Ive tore off numerous roofs with 1, 2, 3 layers. Unless you got 1 million square not much difference honestly.

IMHO anyways...

 

[darkk]

I never do 2 layers, just personal preference I guess...

 

[signcrafter]

I've read a lot of opinions on other sites about this but very little to back it up. There are a number of caveats to doing an overlay--shingles can't be curling (mine are not), new shingles need to have the same exposure to lay correctly (can do), and the decking must be in good shape.

I read thru several warantees and there is nothing there that says overlays void the warantee. That said, the warantees on these products stink (prorated) and labor is the big thing.

The concept of inspecting the decking is the only valid issue I have seen. I have been up in the attic and seen the underside as well as walked the roof and all seems solid. I am trying to get this done before I have any issues. My existing shingles are not leaking but some spots have little to no mineral left on them. The ridges are cracking. It could last another couple years but that would risk problems. I'd rather fix it now.

Big savings for the overlay is labor if I do it myself. Also I can go slower--one section at a time--and it would be easier to follow existing courses. Current roof has no drip edges installed, I can order drip edges intended for overlays and actually have a better roof. Biggest concern for me is doing the valleys--I don't like the way the old ones were done -- they just don't look like water would flow right over them.

ArkTinkerer

Ridges are cracking, don't like the valleys, no drip edge. Sounds like a poor roof, even though you say it is in decent shape. Do yourself a favor and tear it all of and start fresh. You can put down ice dam, drip edge, do the valleys right, etc. Why go over stuff you aren't sure about like the valleys you say you don't like the way they are done.

You can do what you want because it's your roof but any decent roofer would tear it off and start fresh for numorous reasons. I see no reason that a home owner wouldn't want to do the little bit of extra labor to do the job right themselves.

 

[ArkTinkerer]

I'm in Arkansas. Very few houses here have drip edges--they just run the shingles beyond the edge by about 1". Even fewer ice shields--we are lucky to get one snow a year and its gone in a few days. Roof has no sag and the lines are very straight.

But the roof is old. Its done its thing for at least 20-25 years and I've been here for 14 of those and I want to fix it before its a problem.

Best argument against so far is tear off allows inspection. But I can inspect from the attic for the most part.

Arguments for overlay are labor, cost, convenience.

I appreciate the advice so far but has anyone personally seen a problem on a second layer of shingles if its well installed and the deck is solid?

ArkTinkerer

 

[RECox286]

We never layered any roof we ever did. Sometimes the deck was in OK

shape, sometimes there were surprises that reared their ugly heads when

the felt was peeled off. Since we live and worked at the shore, we found

a lot of bad flashings, steel, copper and aluminium alike due to the salt,

humidity, and aging of the materials. If the roof shingles are wood to

begin with, normally they as well as the lathe needs to be stripped off

so a proper deck can be applied. Too many factors to consider b/c

the underside of the roof hasn't been looked at in how many years, and

won't be for another how many. While you are at it, consider a 40yr

architect overlay shingle so, like me, you will never have to fool with it

again in your lifetime. Some last thoughts: don't rely on the cheapie stack

pipe flashings. Have a tinknocker make up a proper flashing that folds

over and into the stack. We have seen too many cheapies fail long

before they should. Also, Ice and Fire applied around the whole perimeter

of the roof is an excellent idea, as well as using 30# felt (minimum). I know

that it ups the cost somewhat, but there is nothing like buying a good

insurance policy for the stuff that lives under the roof.

Uncle Bob

 

[rburke65]

You are adding a lot of weight to that roof system......strip it!

 

[bczygan]

I've read a lot of opinions on other sites about this but very little to back it up. There are a number of caveats to doing an overlay--shingles can't be curling (mine are not), new shingles need to have the same exposure to lay correctly (can do), and the decking must be in good shape.

I read thru several warantees and there is nothing there that says overlays void the warantee. That said, the warantees on these products stink (prorated) and labor is the big thing.

The concept of inspecting the decking is the only valid issue I have seen. I have been up in the attic and seen the underside as well as walked the roof and all seems solid. I am trying to get this done before I have any issues. My existing shingles are not leaking but some spots have little to no mineral left on them. The ridges are cracking. It could last another couple years but that would risk problems. I'd rather fix it now.

Big savings for the overlay is labor if I do it myself. Also I can go slower--one section at a time--and it would be easier to follow existing courses. Current roof has no drip edges installed, I can order drip edges intended for overlays and actually have a better roof. Biggest concern for me is doing the valleys--I don't like the way the old ones were done -- they just don't look like water would flow right over them.

ArkTinkerer

Shingling over is plain and simple a cheaper, crappier way to do it. But go ahead and find reasons to talk yourself into doing that if you like. You may end up convincing yourself that you're happy, but people who know what's what will know you took the shortcut. I'm a builder and would never even remotely consider doing that to anyone, friend or enemy. Anything worth doing is worth doing right, or not at all.

 

[Rust]

Tear it off..and ridge vent is practicly useless without venting at the soffits.

 

[GirlnAgarage]

ArkTinkerer, you've been given reasons to strip it. If they aren't strong enough for you, it's your roof, by all means do it how you want. But seems like you want a blessing before you go ahead. Here you go - good luck!


If the amount of work/work speed is what's making the layer look like an acceptable compromise (you did say "Also I can go slower--one section at a time--and it would be easier to follow existing courses."), then paying for roofers to get it done at a good working speed would be a plus.

Anyway, do it how you want. It's your house.

 

[dirttracker18]

You seem to be looking for someone to give you the OK that you can do it.

It's your roof so you do not need anyones blessing. The overwhelming majority on here are saying to do it right and strip it. However you continue to come back and lean towards another layer.

Plain and simple it is the cheap and wrong way to do it. When you have a problem in a 5 years the only way to fix it will be to strip. Do one layer now and you can make small repairs if needed. BTW, drip edge is not just for snow, but any water coming off your roof.

Your roof, your time, make a choice and run with it. You know what most of us would do.

 

[CodyY]

I'm a roofer in DFW, with an architecture degree.

Strip it. Leave old felt. New 15lb felt over that then Gaf timberline

The insurance companies don't like the additional weight on the rafters. Tear-off costs me a whopping $10 per square. It's worth it.

 

[CodyY]

For the most part I would strip it down for many of the same reasons mentioned like weight and check condition of underlay. I would also say though that if you go to a class 4 shingle with some insurance companies you can get a healthy discount on your homeowners insurance. Yes a metal roof is good, but I know on the old metal roofs that it could get noisey during heavy rain or hail. Also I saw on one policy that you would need to sign a waiver on the appearance of the metal roof for a discount.

Best deal in class4 is Owens Corning Weatherguard HP. about $30/sq over a 30yr shingle

 

[signcrafter]

It sounds like you already have your mind made up and it is your house so do what you want and best of luck to you.

What I don't understand is you ask a question looking for advice and almost everyone advises you to tear it off for various reasons. Yet you seem to keep trying to justify not tearing it off, or at least that is what I get out of your posts. So why ask if you don't want to hear what others are telling you?

 

[ra42mario]

I Just redid half the roof on my shop (hip roof). We stripped it, you would be surprised by the amount of bad wood that you could never see.