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

ArkTinkerer · Jun 18, 2012

I do have a strong bias for not doing the tearoff--I don't think I'm up to it time and labor wise. That means paying to have it done. Big difference in $$$ and might even make me delay the job for a year or two.

Its clear people have a strong bias against it and thats why I ask. I do think inspection is the only valid argument people have presented so far. I discount statements like "Shingling over is plain and simple a cheaper, crappier way to do it. " because it has no info on why its "crappier". What I read agrees with this if the shingles are broke/curling etc. but that is not my roofs condition. I've heard of people doing a bad installation--bad flashing, short nails, bad valleys, etc. But if I pay people I will be subject to the same risk at higher cost. If I do my own overlay, I trust myself to do a good, if slow, job. Knowing WHY an overlay is inherently bad is very important to me in making an informed decision. The WHY seems to be missing from the opinions listed here.

ArkTinkerer

dirttracker18 · Jun 18, 2012

ArkTinkerer said:
Its clear people have a strong bias against it and thats why I ask. I do think inspection is the only valid argument people have presented so far.
ArkTinkerer

WEIGHT - have you ever carried a single bundle of shingles?

Higher likelyhood of future leaks

Much higher difficulty of determining location of future leaks.

did I mention the added weight

your aforementioned valley issues

it's poor workmanship

weight

when your underlayer does start to curl, your new shingles will be lifted

added heat to first layer of shingles

weight

GirlnAgarage · Jun 18, 2012

ArkTinkerer said:
The WHY seems to be missing from the opinions listed here.

ArkTinkerer

No, they're not missing. They were written in plain English. You are refusing to acknowledge the importance of the reasons given.

Instead of accusing everyone here of not providing info, you could say "Thanks for the info but I think I'm going to just do the overlay."

ArkTinkerer · Jun 18, 2012

>>Weight
Read this before, but not too concerned.

>>when your underlayer does start to curl, your new shingles will be lifted
..
>>heat

Thank you! These are two new to me and make some sense. So the underlayer will curl later even though its not exposed? The heat of the underlayer--what is the effect of this? Decking damage, bad seal, cause the curl listed above?

ArkTinkerer

ArkTinkerer · Jun 18, 2012

GirlnAgarage said:
No, they're not missing. They were written in plain English. You are refusing to acknowledge the importance of the reasons given.

Instead of accusing everyone here of not providing info, you could say "Thanks for the info but I think I'm going to just do the overlay."

I apologize if I caused offence. Perhaps I was not clear enough in asking for more detailed reasoning in my posts. I did not mean to "accuse" anyone.

I re-read this thread from the beginning. There are a fair number of posts in this thread that say it is ok or are ambivalent about overlays and my impression was most of those were from people who had done fewer roofs. (One pointed me to a great website with info on this--Thanks!) Some are stridently opposed and they sound like they come from those who do this professionally and do lots of roofs. In my opinion, they didn't give sufficiently detailed reasons. That they have more experience gives more weight to their replies and led me to follow up with more questions.

ArkTinkerer

Falcon67 · Jun 18, 2012

I'll give you one more to confuse you LOL. The open shed at our old property was 16wx22l. Before insurance would write the policy, the agent required that the shed roof be fixed. It had 3 tabs on it that were curling. I started taking it off, and under two layers of gray 3 tab I found these cool green 3 tab shingles. And, they were laying flat, but missing quite a bit of gravel. So - I went over them with the cheapest gray 3 tab shingles I could find at Payless (remember them?) and got the policy written. That was 1997. We sold the house/property in 2010. The house had two roofs during that time due to hail storms and the shed roof had zero. Still looks good. Note that the shed is open in the front and has no ceiling, so roof deck heating was minimal.

On the flip, the house we bought was built in 2001. It has a single layer of standard 20 year gray 3 tabs on it. There were NO upper vents on the roof, just eve vents. (I dunno). First project was to vent the roof. I can still work with the shingles, but I have already replaced a couple from wind damage where the tabs just snapped off. I'd guesstimate the "age" of the roof at about 15 years due to the excessive heat trapped up there by the screwed up venting. They are not curling, but they feel rather fragile.

NUTTSGT · Jun 18, 2012

The reason the majority of people are telling you to strip it is because of experience. With experience, comes knowing what's the right way and wrong way of doing something.

Enjoy you're roofing project, drink plenty of water (gatorade/powerade), I'd suggest you wear tennis shoes as they are easier on the shingles you have already put down and stay off the roof when it gets really hot, you'll distort/tear your new shingles.

SuitorsGarage · Jun 18, 2012

Your nails are going to be going through more shingle material and are not going to hold the shingle down as well as if you stripped the roof making it more prone to a blow off. Also more prone to have a nail pop (lift).

Your shingles may look like they are not curled at all but if they are in the least your new shingles won't be sitting as flat as if you tore off your old roof. Then your new shingles will curl easier and more.

On your valleys that you don't like the way they are shingled. With an overlay the leading edge of the valley shingles that you are not happy with will still be exposed.

Time wise. You do not need to strip the whole roof all at once and bang shingles until you are done. Depending on how your roof is cut up you can probably rip and roof an area at a time. The time you spend actually ripping the roof and getting rid of it is a lot less than applying the new roof.

Roofing is kind of a sucky job and I'm sure that everyone (like me) was just trying to get you to do the best job possible the first time to avoid any problems with the best craftsmanship.

BD1 · Jun 18, 2012

Just curious, what centers are your roof rafters on ? Are they trusses out of 2/4's ? What is the existing sheeting thickness and material type ? Check thickness by looking at roof vents.

ArkTinkerer · Jun 18, 2012

Rafters not trusses. 2x6 with 24" spacing. 1" (3/4" finished thickness) lapped pine for decking.

ArkTinkerer

bob15 · Jun 18, 2012

Art, I counted (quit about 2/3 down) 7 people tell you WEIGHT. Yet you still ask for reasons. Here is another, you'll help keep the land-fill people happy by stripping the roof.

You have 2x6 rafters 24"OC, strip it.

What state do you live in?

Zeke · Jun 18, 2012

ArkTinkerer said:
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?

No. But the roof will look lumpy. If that is not an issue, go ahead, IMHO. The worst overlay is fiberglass 3 tab over wood shingle. I can't stand that. Architectural fiberglass over 3 tab should actually look fine. Here in SoCal we don't get to do overlays anymore. We have to sheet the roof for horizontal shear (even though the sheathing is not truly horizontal, it creates rotational shear).

What's wrong with the valleys? Are they woven or is there a pan? You can lay in a valley pan if there isn't one. Lay it right over the weave. You might want to cut the weave down the valley line.

ArkTinkerer · Jun 18, 2012

bob15 said:
Art, I counted (quit about 2/3 down) 7 people tell you WEIGHT. Yet you still ask for reasons. Here is another, you'll help keep the land-fill people happy by stripping the roof.

You have 2x6 rafters 24"OC, strip it.

What state do you live in?

Arkansas

Based upon the online calculators I should be able to handle a second layer of shingles and about 6" of wet snow which is beyond the worst I have seen here in 20+ years.

Thinking about stripping it because of the comment about "nail pops". Those I have seen here even with single layer of shingles. If a second layer makes this more likely it would actually be "probable" here. Don't know the cause but it happens on about a third to half the houses I've seen when the roofs age. Anyone from the sun belt seen issues with this even without overlayed shingles?

ARKtinkerer

HarleyArley · Jun 18, 2012

I can't give you an example of a problem due to putting on a second roof, but I can assure you it is not wrong or crappy.

I grew up doing roofing, siding and gutters in the Cincinnati area. My grandfather ran a roofing business, my father roofed as a side income, and I grew up from about age 8 on their jobs and did about 2 dozen myself while in high school. Over those three generations I have never heard of a problem due to roofing over an existing layer of shingles which were sound. Every home owner had our business card and our absolute assurance that any problem would be addressed to their satisfaction. We would periodically get a call back... maybe one every 3-4 years due to step flashing or something similar that didn't seal right, but I can never recall an issue as a result of putting a roof on over an existing roof. If the existing roofing was in bad shape or the homeowner requested it we'd tear it off, but the vast majority of our re-roofs went on over existing roofs. However, two roofs max was our policy. Due to roof loads, we never put on a third one.

I have no idea why the majority of the folks here are so nervous about a second layer of roofing.

I hope this helps.

sirsloop · Jun 18, 2012

I've done both ways and didn't live in the place long enough to ever know the difference. I bought my current house with 2 layers already on it. No biggy, IMHO. I guess next time I do the roof I gotta get a dumpster and pull em

signcrafter · Jun 18, 2012

ArkTinkerer said:
Rafters not trusses. 2x6 with 24" spacing. 1" (3/4" finished thickness) lapped pine for decking.

ArkTinkerer

I would not ever do a layover with 24" center rafters due to weight. How many square roof do you have?

The problem with not tearing off and just going over is just because the shingles aren't curling doesn't mean they are in good shape. When you do a new roof you put tar paper down and then the shingles have tar strips that seal to the tar paper. If you just go over the top of the old shingles you are trying to seal to old shingles that may not be in the best condition. Your shingles may look great but they might actual not be good for laying new shingles on.

The number one reason is you will never get as good of a seal going over old shingles as you would by starting on a fresh, clean, flat surface. You may get a decent seal but you won't get the best seal you can if you start fresh. Things like moisture creating algea and mold, wind pull up, water leaks, etc. Also when you try and go over an existing roof the shingles will not be going down on a flat surface like they are designed to do so they can actually "tear" after a few years of settling.

dirttracker18 · Jun 18, 2012

HarleyArley said:
I have no idea why the majority of the folks here are so nervous about a second layer of roofing.

It was common practise 30 years ago but has fallen out of favor.

That is no longer the case. The labor cost to strip is minimal in the overall reroof.

Best practise now is to strip and instal new products under the shingles and inspect. It is now also common to find a shorter lifespan when layered.

If you plan to keep the house you strip and reroof. If you are going to sell in the near future layering is common to "get by."

HarleyArley · Jun 18, 2012

signcrafter said:
When you do a new roof you put tar paper down and then the shingles have tar strips that seal to the tar paper. .

Ummm, the only course of shingles that the tar strip seals to the tar paper is the starter course. Everything else is new shingle to new shingle.

HarleyArley · Jun 18, 2012

HarleyArley said:
Ummm, the only course of shingles that the tar strip seals to the tar paper is the starter course. Everything else is new shingle to new shingle.

Actually that isn't correct either... the tar strips are on top and NONE of them seal to the tar paper.

HarleyArley · Jun 18, 2012

dirttracker18 said:
It was common practise 30 years ago but has fallen out of favor.

That is no longer the case. The labor cost to strip is minimal in the overall reroof.

Best practise now is to strip and instal new products under the shingles and inspect. It is now also common to find a shorter lifespan when layered.

If you plan to keep the house you strip and reroof. If you are going to sell in the near future layering is common to "get by."

I cannot comment on current best practice as I have not roofed professionally in 20 years. However, I have torn off re-roofs my grandfather did after 25+ years on at least two occasions I can recall. My father and I did the jobs when the customer called my grandfather who'd originally roofed the house asking who he'd recommend.

The re-roofs seemed to hold up just fine back then. Its possible that the shingles aren't the same as the used to be. I'm just passing on my experience.

dirttracker18 · Jun 19, 2012

HarleyArley said:
The re-roofs seemed to hold up just fine back then. Its possible that the shingles aren't the same as the used to be. I'm just passing on my experience.

That is a very good possibility as nothing seems to be built as good as it used to be

bczygan · Jun 19, 2012

Shingles HAVE changed. They used to be asphalt based and are now FG. Also lighter weight.
BTW, It is fun, quick and easy to strip a roof. I haven't heard a good reason not to.

Zeke · Jun 19, 2012

Your kind of fun is strange.

The funniest thing about this whole thread are the comments about not putting a 2nd layer over a bad roof (of course not) but it seems like they were saying only over a good roof.

Who would put a new roof over a good roof?

olytdi · Jun 19, 2012

zeke said:
your kind of fun is strange.

The funniest thing about this whole thread are the comments about not putting a 2nd layer over a bad roof (of course not) but it seems like they were saying only over a good roof.

Who would put a new roof over a good roof?

exactly!

HarleyArley · Jun 19, 2012

Zeke said:
Who would put a new roof over a good roof?

By good roof, I mean one that isn't leaking yet. Most roofs will keep out water long after their physical appearance says they are shot. Most home owners look for a new roof before a leak occurs. Obviously, any area with a know leak needs serious inspection to ensure the decking is still sound and will not cause future problems.

However, if the roof has not leaked, a second layer of shingles isn't the end of the world in my opinion. Even if the original 3 tabs are curled in places it still works. You simply adjust your courses to nail though the tabs of the old roof.

All that said, there are certainly only a few disadvantages to tearing off the old roof. They include waste disposal, labor, and the risk of serious damage to the home if a serious storm comes up before the roof can be restored. None are show stoppers. A tarp and a zero risk mentality should deal with the storm angle. The rest is just a bit of time and money.

So what would I do if I planned on staying for 30+ years? Barring serious financial limitations that prevented it, I'd tear it off and put all new materials in from drip edge, to ice shield, to felt, to shingles, to ridge vents, to vented soffits. It may not be essential, but its the safer course of action. If it went to **** early, I could say without a doubt it wasn't for lack of trying.

Rust · Jun 19, 2012

lol
This thread reads more like a philosophy class than a thread for advise on roofing.
Procrastination is usually backed up with alot of words.
:thumbup:

At this point, I'd just tarp it.
If you triple then up you can get at least five more years. Not to mention the cash you'd save...

I drive by this house every day.
It started with one shingle blown off a few years ago. Someone attempted to repair it, hence the kickers, and never went back. I took this photo today, just for this thread.
:beer:

kwb · Jun 19, 2012

For what you can get a decent roofing crew to do a roof for compared to your buying power of roofing (little to none) skip the DIY, have pro's come in strip and reroof and they will be out of there in a day or two.

Guys that did my house (44 square) were only about 35% over the material price that I could have gotten for a 30yr roof and they did it with lifetime (50yr) material. All I had to lift was a pen to write a check.

My brother when he built his shop (20square) went for 30yr materials and it was less than a grand more than what he had in a bid for the materials and was done in half a day.

NFW would I ever do my own roofing beyond a garden shed again after realizing this.

El Barto · Jun 20, 2012

bczygan said:
Shingles HAVE changed. They used to be asphalt based and are now FG. Also lighter weight.
BTW, It is fun, quick and easy to strip a roof. I haven't heard a good reason not to.

Hmmm, I'm just checking your location to see how I can get you to come to my house for a weekend.

Zeke · Jun 20, 2012

kwb said:
For what you can get a decent roofing crew to do a roof for compared to your buying power of roofing (little to none) skip the DIY, have pro's come in strip and reroof and they will be out of there in a day or two.

Guys that did my house (44 square) were only about 35% over the material price that I could have gotten for a 30yr roof and they did it with lifetime (50yr) material. All I had to lift was a pen to write a check.

My brother when he built his shop (20square) went for 30yr materials and it was less than a grand more than what he had in a bid for the materials and was done in half a day.

NFW would I ever do my own roofing beyond a garden shed again after realizing this.

You must live in a state where insurance is cheap or non existent. In CA, roofer workers comp runs over 100 %. That means I pay 20 bucks an hour to the roofer and over 20 to the ins co. Then I pay his SDI, SS and UI. He gets 14 net after withholding; he costs me 50/hr. I charge 100 and make little because 40%+ of my income goes to taxes and SET.

kwb · Jun 20, 2012

Washington by most standards is not cheap for insurance not sure the state industrial rate for roofers but it was listed as very high for construction in general in a recent initiative that was up for vote that would have changed the system by a long shot.

I just know what I had for materials bids and I know what I paid my contractor - who checked out for insurance, bond, etc before I selected them.

SARG · Jun 20, 2012

As many have already said ... strip it down and do it right ..... and I would also suggest GAF architectural shingles only.

They seal the best... they seal the fastest .... and they last the longest.

ArkTinkerer · Jun 21, 2012

kwb said:
For what you can get a decent roofing crew to do a roof for compared to your buying power of roofing (little to none) skip the DIY, have pro's come in strip and reroof and they will be out of there in a day or two.

Guys that did my house (44 square) were only about 35% over the material price that I could have gotten for a 30yr roof and they did it with lifetime (50yr) material. All I had to lift was a pen to write a check.

My brother when he built his shop (20square) went for 30yr materials and it was less than a grand more than what he had in a bid for the materials and was done in half a day.

NFW would I ever do my own roofing beyond a garden shed again after realizing this.

Pricing is quite different here. About 30 square to the job. About $3k for shingles $4.5K for labor for tear off/reroof. Nothing really special--single story, moderate slope, one chimney, about 6 vents thru the roof. Had two quotes and they are similar.

I have to work more hours to clear 4.5K after taxes than I think it would take me to do the job myself. If I do an overlay its a no-brainer--I'd do it myself. Tear off leaves the roof exposed for a longer period of time or makes it harder to do in sections on Saturday mornings.

Still researching the nail pop and sealing issues of an overlay.

ArkTinkerer

WVBrady · Jun 21, 2012

ArkTinkerer said:
.... Tear off leaves the roof exposed for a longer period of time or makes it harder to do in sections on Saturday mornings...

I'm planning on removing mine in sections, just what I can get recovered that day (or longer non-rainy period).

Zeke · Jun 22, 2012

WVBrady said:
I'm planning on removing mine in sections, just what I can get recovered that day (or longer non-rainy period).

That is a very good way to go. Strip and lay down the underlayment for an entire shed section. Only too much sun or a nasty storm will mitigate that plan. do 'em one at a time and run the ridge last. Not much rain falls on the ridge.

bczygan · Jun 22, 2012

I don't know if the question was asked and answered, but the first questions should have been "Have you done this kind of roofing before?" Is it a simple roof? Do you have any "grunt" help? Are you in good physical shape and in the mood for this kind of physical work?
Are you going to hand nail or use a power nailer?
Are you going to hump the bundles up or have them roof delivered?
Is it all 1 story and low slope?
What's the weather?
Have you got adequate tarps for the debris and to cover in case of rain?

Your posts and detailed questions seem to indicate that you are inexperienced with roofing and wanting to learn which is good. So take the expert advice offered here.

If it is just you doing the work, you can do it, but plan to work in stages.
It is monotonous, hot and physical work.
Stripping is physical but satisfying as you see a big change as you remove the old shingles. Pulling stray nails will be tedious. You will then see the decking boards and find the ones that need replacing. And there will be some. You will also see all the vent and flashings and have the opportunity to make any changes to venting or flashing. Also, you will have the opportunity to use ice and water shield and a good underlayment.
You will work way slower than an experienced crew. If you can make more per hour in your work, you won't save money, but if you are using free time, it pays to do it yourself. You will be able to guarantee quality.

As far as having it done, there are crews and there are crews. You will spend time and effort finding the right one. Roofing is like carpet install, a trade where some contractors can make a bunch by using the worst (And cheapest) crews and cutting corners to make the most money. A friend ran 2 crews. One could work alone. The other was dragged out of bars and he had to watch them every minute.

On a sizable roof you will be so tired of roofing by the end, that you will never want to look at another one. But you will have the exhausted satisfaction of a big job well done.

What color are you planning on?
3 tab or dimensional?
Closed cut valleys?
Place your drip edge so it is 1/2" out from the edge of the fascia.
Do you know which way the prevailing winds are so you know which way to run the cap shingles on your ridges?

djd99 · Jun 23, 2012

It's unbelievable to me that there are so many people willing to spend others money so quick. I'm still old school and would have absolutely no issues with throwing a overlay on with Architectural shingles. If your current roof isn't leaking and you know your deck is solid, really you could get another 30 years out of a overlay. As a fact I'm going to do the same thing in the next 5 years. I know several of my friends I helped overlay with their house and none of them leak. Do what you want to do Is all that matters anyway.

CodyY · Jun 26, 2012

djd99 said:
It's unbelievable to me that there are so many people willing to spend others money so quick. I'm still old school and would have absolutely no issues with throwing a overlay on with Architectural shingles. If your current roof isn't leaking and you know your deck is solid, really you could get another 30 years out of a overlay. As a fact I'm going to do the same thing in the next 5 years. I know several of my friends I helped overlay with their house and none of them leak. Do what you want to do Is all that matters anyway.

You're Old school.
I'm a construction manager for a roofer with an architecture degree or three.

Strip it, my cash price during storm season is $200 a square for O-C or GAF "lifetime", including drip edge and penetrations. I can buy the material for your job for almost HALF what you can. It would be done in a day or less and ya don't have to **** with it.

Or risk your old *** falling off the ladder and having a 60lb bundle land on you

johncarton · Jun 26, 2012

i think Big Poppa said right......

wouldworker · Jun 26, 2012

I have had a roof replaced due to hail damage 2 different times. Each time the insurance adjuster said to tear off the old roof--adjusters said it is common practice in the industry at this time.

CodyY · Jun 27, 2012

wouldworker said:
I have had a roof replaced due to hail damage 2 different times. Each time the insurance adjuster said to tear off the old roof--adjusters said it is common practice in the industry at this time.

Because of the additional weight on the rafters.

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

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