Roofing discussion!!!

[nwut05]

Hello all, I just wanted to get some other opinions and objective discussion about a situation i came across this weekend. I observed a roofing contractor who installs a lot of tin roofs. He was doing something i thought was maybe worth discussing. I observed him working on an existing roof that was shingled and he was putting new tin over it. Now here is the questionable part. Instead of rolling the tar paper/felt the length of the house, starting at the bottom, and overlapping to the eve. He was starting at the end of the house and rolling from one side to the other overhang to overhang, or gutter to gutter per say, overlapping as he went about 8 inches. Now i do know this contractor somewhat, and confused about his new tar paper technique, i approached him. I had to ask him why he was doing that? and his response was it did not matter which way he ran the tar paper over existing shingles???? and after some friendly discussion i decided the best thing i could do was move on and not try to change his mind anymore! So what do you guys think will his way work. i personally think it would open up more opportunity for leaks????

 

[BLSXJ]

Well a quick look found The Purpose of Roofing Felt - Is Roofing Felt Necessary? - IKO Roofing

running the tar paper vertically, would eliminate the water proof benefit

but it would still help even out the shingle surface.

my vote was either it doesn't need to be done... or he was doing it wrong.

 

[ovrszd]

It certainly wouldn't be easier to run it that way. Well, to me, it wouldn't be easier.

So this completed roof has a layer of tar paper, a layer of shingles, a layer of tar paper and tin sheeting.

I can't see that the newly added layer of tar paper is doing much anyway?

And if the roof develops a leak it probably won't breach the vertically ran, 8" overlap anyway.....

I'll yield to the expert and say it doesn't matter.

 

[davedj1]

The paper isn't for waterproofing, it's simply to keep condensation from dripping inside. If it already has a shingled roof ( I wouldn't put tin over a shingled roof) I see no need to install tar paper. If the roof shingles are bad enough to need tin, they should be torn off and thrown away.
Any of you seen paper on a pole barn? If so, how was it put on? It would be difficult at best to run it laterally.

 

[Dwellonroof]

The tar paper is actually a slip sheet at that point.
It is a barrier between the granular surface of the shingles and the underside of the metal roof.

 

[Steppenwolfe]

I wouldn't run metal over shingles... spend a few bucks and do it right.

 

[ovrszd]

I wouldn't run metal over shingles... spend a few bucks and do it right.

If you are gonna say that you should describe "right".

 

[RalphVa]

Hello all, I just wanted to get some other opinions and objective discussion about a situation i came across this weekend. I observed a roofing contractor who installs a lot of tin roofs. He was doing something i thought was maybe worth discussing. I observed him working on an existing roof that was shingled and he was putting new tin over it. Now here is the questionable part. Instead of rolling the tar paper/felt the length of the house, starting at the bottom, and overlapping to the eve. He was starting at the end of the house and rolling from one side to the other overhang to overhang, or gutter to gutter per say, overlapping as he went about 8 inches. Now i do know this contractor somewhat, and confused about his new tar paper technique, i approached him. I had to ask him why he was doing that? and his response was it did not matter which way he ran the tar paper over existing shingles???? and after some friendly discussion i decided the best thing i could do was move on and not try to change his mind anymore! So what do you guys think will his way work. i personally think it would open up more opportunity for leaks????

Don't think I want to use that roofer. Don't like the idea of putting tin over shingles. Not the most even base. Certainly would have want him to be rolling the tar paper vertically.

Ralph

 

[TnAndy]

The tar paper is actually a slip sheet at that point.
It is a barrier between the granular surface of the shingles and the underside of the metal roof.

That is the reason I'd use tarpaper over shingles IF I was going to install metal over shingles....which I wouldn't personally.

 

[Diggin It]

'A few bucks' could double or triple a job cost. I've got over $7,500 in my metal roof and that's over existing shingles. No way I could have afforded a full tear off. I don't know how long it will last before problems develop, but I hope I'm long gone before then.

 

[ovrszd]

Don't think I want to use that roofer. Don't like the idea of putting tin over shingles. Not the most even base. Certainly would have want him to be rolling the tar paper vertically.

Ralph

As I said to Steppenwolfe, it don't like the idea, tell us why? And explain how it should have been done?

 

[ovrszd]

'A few bucks' could double or triple a job cost. I've got over $7,500 in my metal roof and that's over existing shingles. No way I could have afforded a full tear off. I don't know how long it will last before problems develop, but I hope I'm long gone before then.

That's why I keep asking for explanations. Easy to condemn a method if you don't have to explain reasons and cost to do it the "right" way.

 

[Diggin It]

Every contractor and supplier I talked to said to nail 1x4s over the existing shingles and screw the panels to those. None mentioned paper.

The only alternative was a full tear off down to the decking, replace/repair any bad boards, then apply paper, then the 1x4s and panels.

 

[nwut05]

Thanks for the input so far, I never thought about it just being used as a barrier between the shingles and the tin for abrasive block. I was only concerned about the water leaking from either rain or condensation. But that's why i wanted to get other input. I am not a proclaimed builder, carpenter or roofer. but I did build my own house, took 3 1/2 years but i did it slowly from ground up and passed all inspections through the county, when building inspector came out periodically.
ALSO:
During my conversation with this roofer as to why he did it this way, the subject of stripping the tin also came up. you know putting wooden strips between the tin and the sub-roof, and he stated he was against that also. His reasoning was that tin will condensate when cold air gets under it. and those bigger air gaps created by the stripping would let the tin condensate easier/quicker. ??? again i do not know if he right or wrong just seen a use of felt that i thought was improper. and this curiosity and conversation led to other things, and before feelings got hurt i quit and went back to feed'n cattle with a few more questions than answers and thats why i put it out here.

 

[Diggin It]

His reasoning was that tin will condensate when cold air gets under it. and those bigger air gaps created by the stripping would let the tin condensate easier/quicker.

And mine told me just the opposite ... that the gaps would allow better airflow from the eave up to the ridge which would help prevent issues.

 

[ovrszd]

I sortta agree with him in regards to condensation.

I built an all metal building 10 years ago. It was a VP building. Came with detailed instructions. Repeatedly talked about not having an air gap between the tin and the insulation wrap. This would create a place for condensation. The insulation needed to be in contact with the tin.

I suppose that same philosophy applies here??

In my world stripping is only done to "level" out an out of shape roof.

 

[East30]

Every contractor and supplier I talked to said to nail 1x4s over the existing shingles and screw the panels to those. None mentioned paper.

The only alternative was a full tear off down to the decking, replace/repair any bad boards, then apply paper, then the 1x4s and panels.

Never done it myself, but have seen it done numerous times this way.

 

[fruitcakesa]

Every contractor and supplier I talked to said to nail 1x4s over the existing shingles and screw the panels to those. None mentioned paper.

The only alternative was a full tear off down to the decking, replace/repair any bad boards, then apply paper, then the 1x4s and panels.

I have used this method on past renovations and also new on my shop minus the shingles.ie: plywood, 30# felt, strapping, metal roof. No moisture issues in 19 years.

 

[jaxs]

As long as it's not my roof I don't see any reason to dwell on it. Just last week I watched 2 "professional"landscape workers spend over 3 hours string trimming the property next door that I've done countless times by myself in 2 hours(often when temperature was 90f +). If the new property owner ask's for my opinion I'll recommend he fire his lawn care company. Otherwise if he's happy I'm happy.

 

[ovrszd]

As long as it's not my roof I don't see any reason to dwell on it. Just last week I watched 2 "professional"landscape workers spend over 3 hours string trimming the property next door that I've done countless times by myself in 2 hours(often when temperature was 90f +). If the new property owner ask's for my opinion I'll recommend he fire his lawn care company. Otherwise if he's happy I'm happy.

So you posted to say your part in this discussion is to not dwell on it. Awesome!!! )