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lemeno 11-11-2007 11:41 PM

shingle over???
hello all,
need to have my roof re-done and was thinking of doing a shingle over to save a little money. I currently have 1 layer of 15 year old 3 tab cheapos. I will be using Tamko heritage 30y architectural AR (which i have already purchased) What are the cons to this? or in the long run would it simply be much better to do a complete tear-off?
My plans were to do the job myself until I moved 100+ bundles to and from the truck and decided that was enough for me. No interest in loosing my back carrying that weight up and down a ladder.

Mike Swearingen 11-12-2007 06:40 AM

I'm not a professional roofer, just a long-time DIYer, but you need to check the manufacturer's warranty. A lay-over may void it completely, and the new shingles won't last as long.
I have always had the old shingles and roofing felt removed, the roof sheathing inspected and repaired if necessary, and then had new 30-lb felt and the new roofing installed per the manufacturer's specs.
We live in a high wind coastal area. The last roof job I had done on our 32' high waterfront A-frame was in 1991 with double bonded fiberglass 40-year warranty shingles requiring eight nails in the edge shingles and five in the field shingles. I also had all edges tarred down 6"-12" with black plastic roofing cement.
We have been through numerous gale force nor'easters, one 100+mile-per-hour water spout, and several hurricanes, including a direct hit from Isabel in 2003, without even losing a shingle.
I don't think that we would have had this much "luck" if we had done a lay-over.
See what the pros have to say.
Good Luck!

MikeWolverton 11-13-2007 11:35 AM

Warranty wise you shouldn't see any void out for laying over existing shingles. There are just a few common things they'll require you to do - such as playing down 30# felt over the existing shingles and cut away any curled up sections of shingles. Laying over the shingles is a fine to do - granted your deck on the roof is in good condition.

If you have a rotted out Deck I'd recommend taking them time to rent a Dumpster and tear the shingles off yourself in a weekend to save costs on labor. Get some friends to come help - offer a 24 pack and some burgers - you'll spend less on that then you would getting some contractors just to climb on your roof. Replace any sheets of or pieces of decking on the roof that have gone bad and begin your roofing process from there. Most Manufacturer's have very detailed instructions on how to roof your house if you never have before.

Ed the Roofer 11-13-2007 12:23 PM


Originally Posted by MikeWolverton (Post 73593)
offer a 24 pack and some burgers

That is some of the most negligent advice I have ever heard.

Get your novice friends drunk and put them on a roof.

One weekend? Be real! Read how long it has taken many other posters on this forum and see that many have given up and hired a contractor anyways.

The new roof will not last as long, because their will be heat sump pockets trapped under the new shigles.

Installing felt paper between the layers is a no-no.

With a reroof, you will not be able to inspect for decking wear and tear and you will not be able to install Grace Ice and Water Shield protection either.

Contractor charge for their insurance, which is steep due to the dangers involved in the work.


perpetual98 11-13-2007 12:53 PM

To be fair, he didn't suggest that he got his friends all liquored up THEN sent them up to the roof. You need to save the beer as a "reward" for when they're done. :)

MikeWolverton 11-13-2007 12:59 PM


Originally Posted by Ed the Roofer (Post 73599)
That is some of the most negligent advice I have ever heard.

Get your novice friends drunk and put them on a roof.

Wouldn't recommend that in the least bit. However there is nothing wrong with drinking after the job is done. I apologize to anyone who might have taken this the wrong way.


Originally Posted by Ed the Roofer (Post 73599)
One weekend? Be real! Read how long it has taken many other posters on this forum and see that many have given up and hired a contractor anyways.

An average Joe with three friends could easily tackle a project of this size in a weekend if they tried. Doing it yourself won't get it done. Only issue that becomes a concern with tearing your own roof off is making sure your contractor who will be 'installing' the new roofer begins work soon as the tear off is done.


Originally Posted by Ed the Roofer (Post 73599)
The new roof will not last as long, because their will be heat sump pockets trapped under the new shigles.

This is 'somewhat' true. Depending on who produces the shingles the warranty will change and may be rated down for shingling over. However there are still Producers who will not rate the warranty down just because you went over existing roof. Given your properly laid the shingles and followed all the rules of the Warranty for laying over.


Originally Posted by Ed the Roofer (Post 73599)
Installing felt paper between the layers is a no-no.

No, it is not a No-no.

Does it need to be done - No, will a majority of Warranty's for the shingles require you to do it - yes.

The longer answer...
If you're installing asphalt composition shingles over asphalt composition shingles, no felt underlayment is needed or required. The purpose of the asphalt felt underlayment under a composition shinlge roof is to provide a barrier between the wood and the asphalt shingles. The existing shingle roof provides that barrier for your new roof.

There's not a down side to installing felt between the two roofs, so if you have a contractor who installed it, other than the extra expense for the material and a little labor, there's not a problem. There's just no benefit.

Reroofs are not the best choice, but it is a workable choice. A tear off will always be better as you will be able to make sure your entire roofing system is up to date with the latest advancements in roofing. Being able to hire someone who is trained and skilled in installing your roof will almost always turn out better with a quality contractor.

^Mike Wolverton

Ed the Roofer 11-13-2007 01:45 PM


Originally Posted by MikeWolverton (Post 73610)

There's not a down side to installing felt between the two roofs, so if you have a contractor who installed it, other than the extra expense for the material and a little labor, there's not a problem. There's just no benefit.

This creates a vapor barrier between the two layers of roof shingles which allows trapped moisture content to not get evaporated through the roof. The bottom shingles, which are the sub-structure base for the new reroof shingles will deteriorate significantly quicker. The shingles below become crumbly and eventually the nails are not set firm and snug against the sub-sstructure base. Nails will be more likely to loosen from expansion and contraction through the toggle affect.

I never count on untrained help to remain on the job for using muscles they are not used to. 1/2 day and they can not keep on going. Now, you have 1/4 to 1/2 torn off and you start taking short cuts just to get it covered up with felt and be water tight.

Yes, it can be done, but only if they are willing to stick it out for the cost of a 24 pack promise at the end of the day. Do you actually think that they will not want a few "tastes" while sweating their butts off?


MikeWolverton 11-13-2007 02:06 PM

Alright Ed, you win. I will agree that there is a chance for moisture to become trapped in between the felt and shingles which can cause issues over time - since moisture build up never leads to anything good.

Now, to redirect to the Original question at hand - this is Tamko's requirements for Reroofing.


Before re-roofing, be certain to inspect the roof decks. All plywood
shall meet the requirements listed in Section 1.

Nail down or remove curled or broken shingles from the existing roof. Replace all missing shingles with new ones to provide a smooth base. Shingles that are buckled usually indicate warped decking or protruding nails. Hammer down all protruding nails or remove them and refasten in a new location. Remove all drip edge metal and replace with new.

If re-roofing over an existing roof where new flashing is required to protect against ice dams (freeze/thaw cycle of water and/or the backup of water in frozen or clogged gutters), remove the old roofing to a point at least 24 in. beyond the interior wall line and apply TAMKO’s Moisture Guard Plus® waterproofing underlayment. Contact TAMKO’s Technical Services Department for more information.

The nesting procedure described below is the preferred method for re-roofing over square tab strip shingles with a 5 in. exposure.

Starter Course: Begin by cutting shingles into 5 x 36 inch strips. This is done by removing the 5 in. tabs from the bottom and approximately 2 in. from the top of the shingles so that the remaining portion is the same width as the exposure of the old shingles. Apply the starter piece so that the self-sealing adhesive lies along the eaves and is even with the existing roof. The starter strip should be wide enough to overhang the eaves and carry water into the gutter. Remove 3 in. from the length of the first starter shingle to ensure that the joints from the old roof do not align with the new.

First Course: Cut off approximately 2 in. from the bottom edge of the shingles so that the shingles fit beneath the existing third course and align with the edge of the starter strip. Start the first course with a full 36 in. long shingle and fasten according to the instructions printed in
Section 3.

Second and Succeeding Courses: According to the off-set application
method you choose to use, remove the appropriate length from the rake end of the first shingle in each succeeding course. Place the top edge of the new shingle against the butt edge of the old shingles in the courses above. The full width shingle used on the second course will reduce the exposure of the first course to 3 in. The remaining courses will automatically have a 5 in. exposure.

Section 1 - Decking

These shingles are for application to roof decks capable of receiving and retaining fasteners, and to inclines of not less than 2 in. per foot. For roofs having pitches 2 in. per foot to less than 4 in. per foot, refer to special instructions titled “Low Slope Application”. Shingles must be applied properly. TAMKO assumes no responsibility for leaks or defects resulting from improper application, or failure to properly prepare the surface to be roofed over.

NEW ROOF DECK CONSTRUCTION: Roof deck must be smooth, dry and free from warped surfaces. It is recommended that metal drip edges be installed at eaves and rakes.

PLYWOOD: All plywood shall be exterior grade as defined by the American Plywood Association. Plywood shall be a minimum of 3/8 in. thickness and applied in accordance with the recommendations of
the American Plywood Association.

SHEATHING BOARDS: Boards shall be well-seasoned tongue-and-groove boards and not over 6 in. nominal width. Boards shall be a 1 in. nominal minimum thickness. Boards shall be properly spaced and

Section 3 can be found on the packaging and on the website. It basically talks about how to fasten down your shingles, where to nail, what type of nails to use and length. Tamko supports the use of Staples with their shingles, I personally suggest against this. I believe Stapling shingles to your roof is just asking for issues few years down the road.

Nails! Nails! Nails!

jogr 11-13-2007 02:14 PM

If you are concerned about your back you certainly don't want to attempt to remove 33+ squares of shingles with or without friends.

Tamko instructions for the Heritage 30 AR say you can roof over but you must inspect the old sheathing and if you are in an area where ice and shield is required their instructions say you must remove the old shingles to a point 24" beyond the wall.

And their instructions don't say to use felt over the old shingles so if you did that then the warranty would be void because their warranty says you must follow their application instructions.

If it were me I'd hire a pro and I'd have them rip off all the old shingles. The tear off doesn't cost that much, your back will thank you, you'll get a good inspection of your sheathing, and the roof will look great.

MJW 11-13-2007 06:11 PM

Doing a house this size isn't a DIY project, IMO. You already did too much work bringing them home yourself.

Certainteed does not warranty an over-lay. In Minnesota it is illegal for a contractor to do. That must mean something, right?

Imagine what prices will be in 7 years when the shingles are already worn out. Now double that for tearing off 2 layers.

My guess...30 square house with two layers 7-10 years from now.........15-20K
Not to mention all the rotten sheathing that will have to be replaced.

I wish you luck to find a Contractor that will get you out this problem. If you could return the shingles, you would have a better chance getting someone reputable to do the work for you. I don't think you will find anyone good that will haul the shingles up the ladder.

the roofing god 11-13-2007 09:10 PM

Ed is right about adding an extra "vapor barrier"(paper causing problems,and it`s not the smartest project for a diy,unless you have a roofer friend to direct you,you will probably end up with more problems than you need :no: ,also check to upgrade your homeowners liability policy,and take out workman`s comp for when someone gets hurt "It`s always when you least expect it,That the worst things happen":eek:

pavola 11-14-2007 09:58 PM

If you're going to do a recover at least use the same size shingle (metric or standard), otherwise you'll have that "beautiful" kick-up line every 6-8 courses. But Ed's right about the moisture problem with or w/o felt between layers. A recover is kinda like repainting over loose paint. Looks bad and you'll be re-doing it a whole lot sooner.

the roofing god 12-01-2007 11:39 PM

typically a reroof over is what we call lighting a fuse because usually the roof doesn`t breathe anymore,and the plywood usually goes bad and needs to be replaced the next time which is generally shorter than the mfgrs implied warranty on the shingles you install

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