# Re-roofing vs tearoff?



## johnk (May 1, 2007)

Alot of people would say that a layover is ok.IMO it's like putting perfume on a pig.Your roof is 18yrs old,some leaks you may never notice.I would recommend a tear-off just for the fact that it does make for a better job.On a layover you still have to cut back your edges,expose all old flashings,remove old ridgecap,replace all boots and vents and cut your ridge for ridgevent.Plus on a re-roof you put down new underlay,ice and water at the eaves and in valleys.I've never seen anyone put new underlay on a layover.But in the end it's up to you,I mean a layover would work but IMO not near as good as a re-roof.Price em both and decide from there. John


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## Ed the Roofer (Jan 27, 2007)

Honestly, it really depends on how true and flat your existing roof is, as long as their are no possibilities of decking issues that must be dealt with. 

Also, if you live in a cold climate, there is no practical way to install the Grace Ice and Water Shiled that most codes now require, so you would be getting denied that additional protection.


Additionally, by doing a lay-over, you are creating "Heat-Sumps" trapped between the two layers, which, along with any trapped humidity or moisture, will decay the new roof shingles even more prematurely.

Finally, as a long term vision, if you intend on staying in the home for about 15 years at least, (because that is about the longest the new roof will last as a lay-over), or if you may be planning on selling in about 10 years, you will have the additional cost of paying for a 2 layer tear-off to be able to re-roof the home at that time. 

I don't know your personal age or your geographic climate, but that could be a major consideration in the long run. If either of those time periods are later on in your maturing, near retirement years, then, the additional costs associated in todays valuation of dollars, would be even more impracticle than currently.

Many home inspectors use the roof age and wear and tear and amount of layers as a key and critical factor in assisting their prospective buyer in negotiating a much better deal at the sale time of price negotiation.

Ed


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## SG94 (Apr 5, 2008)

We're in your neck of the woods... we don't have plans to move in the near future, but I don't know that we'll be here for 15 years either. The more research I do, the more it seems to point to a tear-off. I've talked to a couple of my neighbors, and they've done new roofs, using companies who weren't even on my radar. (and not in business very long, etc.)


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## Ed the Roofer (Jan 27, 2007)

Well, I am in the NW suburbs of Chicago, around the Elgin and surrounding area, and I know quite a few worthy contractors all around the area, if you need any help. 

I've met quite a few worthy and wortless guys over the past 30 years, so i know who really has what it takes to stand behind their work for longer than it takes the tail lights to be out of your line of site.

I have probably put at least one roof on in every surrounding suburb over the years. name a town and I will tell you a job.

e-mail me if you want a direct referral.

[email protected]

Ed


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## Ed the Roofer (Jan 27, 2007)

SG94 said:


> I've talked to a couple of my neighbors, and they've done new roofs, *using companies who weren't even on my radar. (and not in business very long, etc.)*


That would be about 95 % of all companies from what I see.

There are also a lot of fly by night Storm Chasers that show up aggressively every couple of years or so. They last one year after the roof, then close up shop and name and leave the problems for the Home Owner to figure out. They seem to give the trade a bad name, for their lack of quality and ethics.

Ed


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## the roofing god (Aug 2, 2007)

we have done 2 layovers(reroofs)in the last 12 years,regarding ed`s statement:Additionally, by doing a lay-over, you are creating "Heat-Sumps" trapped between the two layers, which, along with any trapped humidity or moisture, will decay the new roof shingles even more prematurely.

In my area,I like to call putting the 2nd layer on top"Lighting a fuse" AS BY PUTTING DOWN A 2ND Layer ,you effectively cut out the breathability of the decking,one of the reasons for spec of 15# felt is allowing the decking to breathe,when that is closed over ,most roofs fall prety to a situation called dryrot where it becomes necessary to replace all of the roof decking next time around(and usually this roofing only lasts around 15 or more years at best before the decking is shot,even though the shingles may still look ok.

Another consideration is the weight especially when you are in the snow belt,2 LAYERS GOES ABOUT .5 LBS OVER THE RATED LOAD OF 4 LBS PER SQ. FT. ON 1/2" PLYWOOD,With a snow load also,the building is prone to stress fractures of framing(akin to settling),and in the sheetrock which can be found at the wall to ceiling juncture,over door openings etc.

also be sure to have proper flashing at gutters,amt. ice and water shield,and proper balance of intake and exhaust ventilation.
To finish,let me say if he is indeed in your area,in my opinion,it would be foolish not to use Ed of right way roofing,as his attention to detail is something to be admired :thumbsup:


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## MK13 (Apr 16, 2008)

I need to redo my 18 year old roof and am considering a layover and appreciate the above posts. The roof has tabless shingles (Certainteed Jet 25 year shingles) that still lay flat, with a weight of 225 lbs. per square, well ventilated by electric attic fans. Given that the shingles still lay flat, given that the hips and the lower 5 feet or so of the roof is covered by an ice and water membrane, would that mitigate the potential problem of trapped humidity or of dry rot (there was appropriate felt underlayment in the initial roof job). My home is in the Central NY (snow belt) area, with half inch plywood and wonder about the significance of the risk of the extra weight (above the 4 lbs. per square inch load rating.) Thank you.


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## Ed the Roofer (Jan 27, 2007)

Although it may lay down flat on top of the original layer, you should expect a decreased life expectancy of at least 25 % from a roofing application that goes directly over the sheathing and new felt paper.

I think the more appropriate answer for you to decide on, is whether or not you intend on being in that home many years down the road.

If your time frame of moving and selling hedges towards around 8-10 years or more, then the disparaging aesthetics of the premature degradation will more than likely become more obvious to a home inspector and a potential buyer, which firstly decreases the initial curb appeal and the 1st perception of the potential buyer and secondly, decreases your negotiating position.

If that is the case, then the existing home owner is usually compelled to have a new roof installed as cheaply as possible, since they would not be the recipient of the new roofing and ventilation renovation values, or they would have their hand forced to lower the asking price, down to a comfortable level that the potential buying party would be willing to offer.

Ed


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## the roofing god (Aug 2, 2007)

mk13- (above the 4 lbs. per square inch load rating.) Thank you.

1st off it`s 4 lbs per sq ft,not inch,2)the ice shield works properly because the displaced material(of the ice shield)from driving a roof nail thru it,nestles under the head of the nail,with a 2nd layer,that snugness between the shingles and ice shield is not so tight,in fact tending to have air gaps where melting snow can follow down the nail shaft into the home,3rd I am from new yorks snow belt,and the fuse situation is inherent there,as well as 2 layersx 225 +4.5 lbs per ft.(over code,although bldg inspector usually lets it slide)3rd add the weight of 2-3 ft of snow to the mix-how could you possibly expect 1/2"plywood to stand up to that,let alone the 3/8th inch plywood you probably have,you will be paying for a new roof either way,whether you enjoy the benefits of a good roof,and pass it on to the next buyer,or you do a cheap job,and have to have the replacement cost taken out of your homes value ,when it`s time to sell--I would pick enjoying the proper roof while I`m there as when you sell,that money will go straight back to your pocket as nontaxable money,that you invested in your home-talk to your accountant


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## MK13 (Apr 16, 2008)

I appreciate the above posts which have stimulated further questions.
I thought it might be helpful to provide some additional background.

I was involved in all phases of the installation of this roof (which was a redo of the prior roof, and we did do a tear-off). In fact, all the plywood in the valleys as well as a number of other plywood sheets had to be replaced due to dry rot. In the original situation there was only passive ventilation and the attic ventilation fans were installed after the tear-off (18 years ago). All the plywood sheets including the replacements were half inch 5 ply Douglas fir, and the new sheets were also pressure treated.

On top of the plywood in the valleys was aluminum flashing embedded in tar and nailed to the plywood. On top of that was our ice and water barrier (fastened by its own adhesive backing, running up five feet on either side of the valley). Over that was rolled roofing, and the final layer over that was shingles. Beyond the valleys, the roof was covered by the felt underlayment with the Jet 25 shingles on top. 

The slope of the roof is 3.5 inches per 12 inches and average annual snowfall in our area is 81 inches. Summer attic temperatures are mostly in the mid 80's and no warmer than 90.

My questions: 1) Why, if the original felt is still there, would there be no breathing (in a layover)?

2) In the case of the new super thick (300 to 400 lbs. per square) layered architectural singles, why wouldn't they also inhibit breathability of the roof in a way similar to the layover?

3) Is the reason for the not so tight snugness between the shingles and the ice shield (in the case of a layover) due to the age of the membrane? 
Does the ice shield membrane still have the chemical properties that would enable it to grab a nail put through it (in a layover) 18 years later? Can the ice shield lose its gripping properties over time and actually fall away from the nail, even in the initial situation?

4) How does the water work its way down the nail shaft in the case of the layover, and not in the initial construction? (By the way, in our original re-do, we did put a little tar over all the nail heads.)

I realize we might need to do a tear-off and I appreciate your comments.


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## the roofing god (Aug 2, 2007)

I`ve typed my limit here,said all there is to say,except that with under a 4 on 12 pitch roof it shouldn`t be a question,but to rip it off,and I wonder how you put that amount of ice shield in a valley(5 ft up either side),i would have centered the 1st sheet,then if I fely I needed more sealed it to the laps yes,but the ice shield only makes allowance for lapping the one side,unless you tar the other---in reality,you could`ve had the roof ripped off by now,what are you really saving,and why would you wantn the extra weight on your roof when it shouldn`t be--and with a 1 layer roof,heat etc,can escape thru the shingle seams,where3as with 2 layers on that is much harder for it to do,and condensation is more likely to form,which will ruin the plywood-good luck


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## Michael Thomas (Jan 27, 2008)

From a home inspection standpoint the biggest problem with lay-overs is that in the Chicago climate comp shingle roof membranes on slopes of 4/12 and greater (that is, most residential roofs) generally _don’t_ leak unless horribly deteriorated.

But the _flashings _at roof penetrations and junctions with other surfaces often _will _ leak unless carefully thought out and installed - and roofers doing a roof-over (which is done instead of a tear-off for only one reason: cost) are often somewhere between careless and contemptuous when it comes to repairing / improving / replacing flashings on such jobs.

So unless it’s the simplest of gable or hip roofs – and even then if you can’t walk the roof to inspect flashings at plumbing stacks, chimneys, electrical service masts and the like – all the inspector knows for sure when he or she sees a new roof-over is that 1) it was likely installed because there was a “roof leak” and 2) there’s a good chance that the actual cause of the leak – a flashing problem - was not properly corrected.

And the roof is even more suspect when – as is often the case – there is evidence that “roofing cement” or other sealant was used in lieu of proper flashing, in which case the inspector has good reason to suspect that even if the roof is not leaking at the time of inspection, it soon will be.

And if you can’t get up under the roof to inspect it from the underside - or you can, but the weather had been dry and you find old find “old” staining of unknown age - then you are really stuck: you know there may be a problem, but you don’t know when or if it will reoccur, but meanwhile your client is paying you for an “answer to the question”, often expects one, and some inspectors have a problem with the words "I just don't know".

This happened a lot here in Chicago last summer – I would see conditions like this:










the moisture meter would verify that moisture was not elevated in these areas at the time of inspection, I would put up a ladder but inspection at the exterior would find not obvious defects, and I would have to tell my client that there had been a previous leak, but that based on what I could discover at the time of inspection I was not able to determine if the newer roof had corrected the problem.

Now if you can find a roofer who will do a first class job on your lay-over - including the flashings - it may be fine for 10-15 years.

But all too often the guy who bids the job to do the job right is going to come in over the guy the cost-conscious homeowner selects to do the job cheaply - and then I'm out there finding leaks in the attic at the chimney... or worse the IR camera is showing leaks at the inside of the dormer or opposite a missing kickout flashing, and the irate homeowner is insisting that there can't be a problem 'cause "It's a new roof".


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## the roofing god (Aug 2, 2007)

wait till you actually need to do it,but before the plywood goes bad,make sure your insulation is up to code,along with your soffit,and ridge ventilation,and most roofs will last longer than you think


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