# Shingle Roof Replacement Questions - Overlay vs Tear-Off /OC vs Tamko



## tecboy (Jun 14, 2008)

I am in the process of getting quotes to replace my shingle roof. Current roof is 3 tab shingle 4/12 pitch hip roof. Existing shingles still lay flat with no curling. I would like to use dimension shingles for my new roof. I have different roofing contractors telling me different things with regards to using dimensional shingles over 3 tabs. I am asking contractors to quote the OC Oakridge shingles. One contractor says laying OC Dimensional over 3 tab is not a problem as long as the existing shingles are flat and i have another contractor saying that only Tamko will lay correctly as Tamko is the exact size as 3 tab and OC is not. On the other hand the OC contractor tells me that the Tamko Algae warranty is not that good. My first question would be..is this true about the different shingle sizes and an dimensional overlay not laying correctly? It seems that the standard 3 tab has a 5" exposure while both OC and Tamko Dimensional have a 5 5/8 exposure. Second question would be which shingle is better OC Oakridge or Tamko Heritage? Would i gain any significant advantage to tearing off the one layer that is already up there?


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## Ed the Roofer (Jan 27, 2007)

To re-roof over an existing 5" exposure with a product that is intended to provide a 5 5/8" exposure, will require about 11% more shingle product duu to the reduced exposure, if the re-roof is done properly, via the "Nesting" method. This means that the first course will have to have the top portion trimmed off about 2 5/8" and each successive course will need to be "Butted: with its top edge to the lower edge of the course of 3-tabs above it.

If they do NOT do the "Nesting" method and install the shingles with the standard 5 5/8" exposure, you will have the under-lying edges of the 3-tab shingles bridging through, or telegraphing through, the newly installed shingles.

It will be less noticeable with the architectural style of shingles, but it WILL occurr. Then, that crease will becom a weak point in the shingle and will eventiually will crack horizontally at every bridged line on every row of shingles.

A re-roof typicall provides at least 25% less lifetime expectancy that a roof application installed on a roof tear-off down to the existing deck, due to addition moisture retained between the 2 layers of roofing and the build up pf heat sumps between the courses.

The product that I believe All roofing manufacturers use for their Algae Resistant, (AR), version of shingles, is manufactured by the 3-M corporation and should produce similar results, regardless of the manufacturer who provides them.

I would be interested in knowing if the roofing contractor that told you of the difference between Tamko and OC has any data to back that up, or if he is just moving his lips to sell you the product that he desires.

Most contractors do not revere OC shingles due to many past issues with excessive sealants which have created horizontal tearing and cracks resulting from not being allowed to expand and contract with a slightly more visquous formulation for the sealant strip tar adhesive.

The tearing problems were much more prone on the lesser weight and lower quality shingles, but it is still a footnote to be considered.

As a personal preference, I like the Tamko Heritage shingles much more. The one recent OC 50 year shingle I installed, (Which was a 40 year several years ago, when I installed it), has shown significant spider-webbing fissures eminating from the surface in as little as one year after application. That was the customers choice, due to color and definitely NOT my referred product of choice to be installed on her home.

Ed


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## Slyfox (Jun 13, 2008)

*Lay-Over:*
*1) Remove small sections of existing roof system for proper inspection of roof deck.
2) Remove tabs of existing shingles (3 courses up from eave).
3) Cut existing shingles overhang on gables back flush and install new dripedge.
4) Remove all existing hip & ridge caps.
5) Remove tabs of existing shingles from all valleys.
6) Visual inspection of all existing wall and chimney flashings (both sub and counter flashings).
7) Installation of new roof system.
8) Clean-up of all debree from old and new materials and hauling them away.
*
*Lay overs can be installed to meet manufacturer specifications and will last their expected life span if properly installed and maintained.*

*You definately want to "nest the shingles, i believe Ed called it" we call it butt and run, you will not notice the lost of exposure from the ground and less exsposure actually gives you better protection from winds, precipt, etc.
*


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## Ed the Roofer (Jan 27, 2007)

Slyfox said:


> *You definately want to "nest the shingles, i believe Ed called it" we call it butt and run, you will not notice the lost of exposure from the ground and* less exsposure actually gives you better protection from winds, precipt, etc.


Sly, I disagree with you on this point, especially regarding wind uplift.

When a cours is installed at a lesser reveal than specified by the manufacturer, that also means that the sealant location will be moved upwards by that same additional amount on the next and all succeeding courses of shingles installed.

This additional lip of those shingles that are now not sealed as close to possible towards the bottom edge, will likely be more suscuptible to wind uplift and blowing off of the roof or minimally, lifting the shingle and separating the sealant from the shinlge, even if it does not blow off.

By the way, we call it a Butt and Run, also, but I did not think a HO would understand what that meant, plus, Nesting is the more commonly accepted term by the manufacturers and the NRCA manual.

Ed


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## tecboy (Jun 14, 2008)

Thanks for the replies...While doing so more research i came across the GAF ELK website. The specs on their dimensional shingles list a metric and english exposure. Metric being 5 5/8" and english being 5". Does this mean that GAF sells shingles in 2 different sizes? I could not find anything regarding this on their website other than the 2 different exposures mentioned in the specs. Are GAF decent shingles? If i can find a 5" exposure dimensional shingle, i would imagine i could do an overlay as the old and new exposures would match?? I did go back to the Tamko website and found they also listed standard and metric exposures for their shingles. GAF, OC, Tamko, Certainteed. I think those are the 4 major shingle manufacturers. Any opinions on best or worst?


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## Slyfox (Jun 13, 2008)

Ed the Roofer said:


> Sly, I disagree with you on this point, especially regarding wind uplift.
> 
> When a cours is installed at a lesser reveal than specified by the manufacturer, that also means that the sealant location will be moved upwards by that same additional amount on the next and all succeeding courses of shingles installed.
> 
> ...


I never thought about that aspect of it, i was looking at how the nailer strip is lowered, thus covers more of the shingle below.
I'll have to think on the sealer strip issue.
I must say tho, out of all the lay overs i have done, i have no issues with wind damage, minus storm damage that is.


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## Slyfox (Jun 13, 2008)

tecboy said:


> Thanks for the replies...While doing so more research i came across the GAF ELK website. The specs on their dimensional shingles list a metric and english exposure. Metric being 5 5/8" and english being 5". Does this mean that GAF sells shingles in 2 different sizes? I could not find anything regarding this on their website other than the 2 different exposures mentioned in the specs. Are GAF decent shingles? If i can find a 5" exposure dimensional shingle, i would imagine i could do an overlay as the old and new exposures would match?? I did go back to the Tamko website and found they also listed standard and metric exposures for their shingles. GAF, OC, Tamko, Certainteed. I think those are the 4 major shingle manufacturers. Any opinions on best or worst?


A well respected man from the National Roof Group commented on this area not to long ago, Quote" All shingles are manufactured to meet the same minumal state an federal codes" End Quote,
Choose the material that best fits the look your going for, and your budget.
If there installed properly, they will last.


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## Ed the Roofer (Jan 27, 2007)

Slyfox said:


> I never thought about that aspect of it, i was looking at how the nailer strip is lowered, thus covers more of the shingle below.
> I'll have to think on the sealer strip issue.
> I must say tho, out of all the lay overs i have done, i have no issues with wind damage, minus storm damage that is.


I really liked your website where you plucked the layover phrase from Sly. You have improved that quite a bit since the last time I looked at it when you first signed up with the National Roofing Group.

Yes, I am right about that aspect, "Technically". But, if the nails are placed correctly and use the correct length and they are al flush instead of cocked and if it is not a new subdivision with little or no trees blocking the wind, I do not think it would be "Critical".

OP, Metric and US Standard shingles are sold by most if not all of the manufacturers, but it is regional, where the different sizes are sold.

Ed


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## Slyfox (Jun 13, 2008)

Thanks Ed,
I maintain the site myself (hobby), so it's constantly changing, for the better i hope.

I wasn't suggesting you might be wrong about the sealer strip issue,
just never thought about it before.

I did a Google search trying to find info- on it, but no luck as of yet.


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## Ed the Roofer (Jan 27, 2007)

I was advised about the negative impact of that application, when a home owner wanted a 4" course application done on a low slope roof, where I had preferred to install a modified bitumen roof.

Certainteed sent me a letter stating that concern and to act accordingly with that in mind. They did not say that they would not warrant it, but they did point out the potential negative consequences.

Ed


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## time2roof (Jun 27, 2009)

*Tamko AR are not Algae Resistant: Algae RELIEF*



Ed the Roofer said:


> The product that I believe All roofing manufacturers use for their Algae Resistant, (AR), version of shingles, is manufactured by the 3-M corporation and should produce similar results, regardless of the manufacturer who provides them.
> 
> I would be interested in knowing if the roofing contractor that told you of the difference between Tamko and OC has any data to back that up, or if he is just moving his lips to sell you the product that he desires.
> 
> ...


 
I have it from Owens Corning printed in a Technical Bulletin update.

Tamko decided that meeting 3M’s 10% copper mix was too cost prohibitive to absorb with the thinking being that only a percentage of the roofs would be exposed to Gleocapsa Magma build-up. The decision was made to forgo the increased production costs to all the line vs. the cleaning cost for a much smaller percentage of the line that actually even makes it back to them on a warranty call back.

The details can also be found in the TAMKO warranty:

Algae Relief” means Shingles which are covered by an Algae Cleaning
Limited Warranty that provides for cleaning of discoloration caused by
certain algae growth. All Heritage 50, HeritageXL, Heritage 30, Elite Glass-
Seal Shingles come with the Algae Relief - Algae Cleaning Limited Warranty
feature. Tuscaloosa produced Glass-Seal Shingles also come with the Algae
Relief - Algae Cleaning Limited Warranty feature. Only shingles designated
as having the Algae Relief feature are covered by an Algae Cleaning Limited
Warranty.


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## Ed the Roofer (Jan 27, 2007)

All of the Tamko Heritage Architectural Shingles that I install, are of the AR variety.

Ed


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## time2roof (Jun 27, 2009)

*Tamko*

We too install TAMKO Hertiages...but Gloecapsa is soo bad in our region, that we warn any homeowner first........we have been in business since 1995......and plan on being around in the future...I do not want anyone coming back at me after a few years complaining about the stains on their TAMKO's...so we make sure they know that AR can mean whatever a manufacturer wants, and not automatically RESISTANT.

I only jumped into your thread because of your questioning if a roofer was "selling" or sharing facts about the TAMKO AR and it's meaning......at my company, we SELL by fact sharing...not slick talking...and in our LIT_BOX, we keep tip sheets by catagory, to leave with a potential customer when an issue like this is raised.


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