underlayment on a go-over ?

I have seen more and more "roofers" using paper and ice & water shield on go-overs Is this common ? I have never once used paper or any underlayment on a go-over. Am I missing something ? >>>

My comments concerned built up roofing membranes over 1 existing roof. I believe BOCA codes prohibit a recover when 2 roofs exist. We also used as a base sheet a product known as Ventsulation which was excellent and could be spot or stripped mopped. The indentations on the sheet permitted the flow of trapped gases and/ or moisture to flow to the extremeties.>>>

Let's just say it might help to consider this type of issue from something besides a box canyon point of view. Maybe lay it out like a typical troubleshooting chart would look with a flow map to help in the process. For example, take what Roofsrus1 is saying about climate. The chart would show the following fork: Roof is located in a climate zone with heavy ice and snow build-up: Yes or No. If yes, proceed to section on ice dam protection. If no, proceed to standard shingle application specs. There would be many such forks in the flow chart. One of them would pertain to recovers. Is recover an approved application by manufacturer and/or code. Yes or No. If yes, is recover an acceptable option for the contractor and homeowner. Yes or no. If yes, is the condition of the existing roof pristine or no. If no, do you mind having dirt, dust, and grit getting inter-mixed with the new material as it is being applied? If no, skip the section on felt. If yes, go to section covering underlayment options.>>>

In order to establish a good nailing base, we will install shingle underlayment and then nail our roof recover. Conditions, weather conditions, here in Oregon are mild enough that a roof covering will last twenty to thirty years per roof covering unlike other areas of this nation. That side you have other conditions that are factored in being; condition of shingles including granular condition alongside condition of roof sheeting allow us to do many, many roof recovers. That being said-do not believe or give us heck about roof recovers. Our neck of the country and its weather conditions are mild enouh that shingles will last anywhere, on recovers, from twenty to thirty years per roof covering. This allows the residential homeowner to save thousands of dollars when the time comes for their houses to be roofed again.>>>

When did allow lay overs here, we never used felt unless we were laying over wood shingles then city code made us put 30# over the wood... thery was it would make for a smoother apperance.... it still looked like cheat. :silly:>>>

Looks like Vaa and elcid did not read the question.>>>

Im a roofer from michigan your allowed 2 layers here. Underlayments on a recover is crazy and a waist of time and money.>>>

I'm right there with you Rozziroofer......Goofy, isn't it?>>>

In FL, two layers are allowed but they just don't work. In addition, if the home goes up for sale, the lender will usually not lend on a "go-over" and the roof will have to be removed anyway.

I have only sold ONE in many years of roofing-- on a barn. I can't see where underlayment would benefit either performance or longevity.>>>

Would like to debate need for a nailed base sheet when redoing a BUR. Direct attachment to an old roof w/ asphalt would mean that you would inherit any and all the deficiences of the old roof; whereas, by nailing thru the original, you would be venting any gases or moisture entrapped in old system. What say you.>>>

I thought the whole purpose of nailing over was for a cheap job. Doesn't all this unnecessary stuff kill the purpose?>>>

Out here in Oregon you are allowed to have three roof coverings on a home before you have to tear down all the way to the sheathing with the exceptions that with each of the second and third roof coverings-the shingles and roof deck that you are replacing with another covering, must, be in good condition with no excessive loss of roof granules on the shingles and no rot on the sheathing.>>>

We used to do them when they were organic. Could stick them with 2 nails and they would stay. ( I speak from seeing 15 year shingles going 20 years, nailed like that, NOT doing it). :)>>>

T-lock, I am in Boston and you can add a second layer but not a third. I laugh when I see this silliness. I think I & W shield and or paper on a go over is NUTS>>>

tinner I understand what ur sayin (dont agree) but what about the amount of heat between the roof and in the attic space ? This I think would cause the 30 year shingle to age quicker. Never had a complaint with a new roof. Go-over or rip-off.>>>

Lay overs are a thing of the past here. Use to be able to have up to 3 layers on a house. City code now is 1, plus most insurance companies want just 1 layer on the house. To many voids between layers for hail to go through. What good is the I & W sheild gonna do stuck to shingles?>>>