Roof Underlayment

[john in la]

Other than cost....

Give me a list of advantages and or a list of disadvantages to using GAF ice and water shield over
the entire roof as apposed to covering the roof with 30 lb felt paper.

Roof will be stripped down to clean OSB.

 

[M-MAN]

Sometimes I tend to go overboard according to my son. He used to do roofing and when I had mine replaced a few years ago he recommended the synthetic. Being old school I had them lay 30 lbs felt and then added another layer of synthetic. A few hundred extra on a roof didn't hurt my feelings at all.

No experience with the peel and stick but I wouldn't want to be the one up there with that thin layer of plastic that you peel off.

 

[Blackhole49]

You leave a lot of info out of the equation. In LA, obviously ice doesn't come into play. For me, pitch of the roof would be the determining factor. I wouldn't waste the money if there is decent slope. Then again, if I were taking it down to the OSB, I would seriously consider Metal. I put metal over my shingleson my house and barns 7 years ago in MI and am very happy with it.

 

[Stephen Newell]

Synthetic felt is the best way to go however it's cheaper without the adhesive. The only place you might need the self adhesive felt is near the edge of the roof where you might have a ice dam or if the roof slope is really low where water may travel uphill a little and run under the joints. If you wanted to go better there is Polyguard 400 which is a foil faced rubber membrane which could be used on a completely flat roof. Since it is rubber when you put the shingles on the rubber would seal against the nails.

I don't use asphalt felt anymore. I took down a good roof one time that was maybe 15 years old and the felt paper under it was completely rotten. I know the main purpose is to protect the roof until the shingles are put on but the felt should help in case of leaks. Wouldn't be much help if it was rotten.

 

[MarkB_MI]

The only reason to use felt instead of peel and stick underlayment is cost. If the stuff you're showing is the same stuff we use up north (we call it 'ice dam' underlayment), it will seal around all the nails. Pretty much eliminates leaks, even in valleys.

I've never had to remove that stuff, but I suspect it's not easy.

 

[DoubleO7]

Mineral faced--- as in roll roofing that has the granular minerals on one side like asphalt shingles??

 

[MarkB_MI]

> Mineral faced--- as in roll roofing that has the granular minerals on one side like asphalt shingles??

It's just a coating of sand-like stuff so you don't slip on it. As far as I know, the coating doesn't do anything once the shingles are down.

 

[Geo-TH,In]

I'm cheap.
I've had a second roof put over first layer.
Never an issue.
Insurance companies pay for a peal off if I have a hail claim.
My roofer puts The ice water stuff in valleys and first 3 ft at the bottom edge.
I'm hoping for hail. The roof on my house is at the end of it's life expectancy.

 

[caterpillar guy]

Black hole has it no more roof replacement with steel. IT will cost more up front but will be the last roof you will need to put on. Steel will be there 50 years from now. Though in your hurricane area maybe the roof comes off often enough that it doesn't pay to put steel on. Let the insurance company put the new roof on in that case.

 

[MarkB_MI]

> I've had a second roof put over first layer.

George, a square of shingles is over 200 pounds. Have you ever calculated how much extra weight your roof is carrying with that extra layer?

I always do a complete tearoff when I re-roof a house.

 

[Janicholson]

You live with Hurricanes and potential tornadoes. I think I would like a stuck down waterproof material under my shingles I also believe in hard fastening rafter/trusses to top plates and wall structures. Jim

 

[john in la]

[b:654c4848f0]I would like a stuck down waterproof material under my shingles[/b:654c4848f0]

That is what I am thinking.
I can tie the studs to the floor and the rafters to the studs with hurricane ties (do not understand why every house is not built using them) the roofing material is the most vulnerable part in a storm.
Even if you can keep the roof structure on the house once the shingles or metal is gone rain water can still do a lot of damage.

I am thinking metal roofing.
Under that 2x4's screwed into the rafters.
Under that a roofing material with foil on one side to reflect heat back up to the metal.

Under that a peal and stick ice and water membrane in the valleys and around the edge.
I do not need it for ice but it helps with water on these edge areas.

The foil backed underlayment is good enough nothing is needed under it but I am thinking of covering the entire roof with the peal and stick underlayment like will be used in the valleys.

My thinking is the foil backed underlayment is nailed down.
If the wind takes the metal off this underlayment will rip up letting water in.
On the other hand the OSB would have to come off for the peal and stick to come off.
For a few hundred dollars I can get the added protection against water if the metal does come off.

I have seen several houses that the metal roof comes off in a storm.
The wind gets under the overhanging edge of the metal a rips it off.
I plan to put gutters around the edge to try and protect against this.

I just do not know if covering the entire roof with a non breathable ice and water dam will cause other problems so I ask the question here.

 

[Stephen Newell]

It's within industry standards to put a second layer of shingles on but when it comes to the third it's better to start over.

 

[Frankmn]

Actually the reason for the felt underpayment is to provide oil on the back side of the skingles to increase their life

 

[Geo-TH,In]

Mark,
I always do a complete tearoff when I re-roof a house.

Don't forget I'm cheap.

I had an old roofer said, the second layer holds up better to hail damage because the first layer acts like a cushion.

If I have to pay for the shingle replacement, it will do a second layer.

Each to their own, I'M CHEAP!
I have 3 roofs that will need replaced soon.
They will get a second layer if I don't get a hail storm very soon. The roofs were replaced courtesy of the hail storm of 1998. That was 25 years ago.

 

[Texasmark]

I had a new 30 year roof installed a couple of years ago. They either used that product or something similar. Having roofed my houses a couple of times I am aware of installing felt paper underlayment. Watching them proved to me that it was a superior product and was a lot easier on the installer and nicer alignment than felt.....also, when you are up there putting the shingles on and it is a hot summer day, you don't have that black hot box staring back at you. Go for it.

 

[dhermesc]

GAF makes some good stuff. I am in the middle of roofing my renter's house I am using GAFF Felt Buster - according to Bob Villa it is the best out there. It is very tough and seems like it should last.

https://www.bobvila.com/articles/best-roof-underlayments/



Like most people I believe in only one lay of shingles on a roof due to weight. The house I am doing was reshingled back in the late 1990s early 2000s and they stripped and resheeted the roof put down a what appears to be 30 pound felt. But they used the cheapest 3 tab shingles they could find. I am peeling the shingles off and have had excellent luck NOT damaging the felt paper. I am leaving the 30 pound felt from 20/25 years ago down and putting the Gaff Felt Buster over it. I had never tried this before because usually the felt is heavily damaged while removing the shingles and everything gets removed. Anyone else tried this in the past?


I bought 4 shingle shovels at an auction last fall for $5 (new about $70 each) and they have made removing the shingles so much easier than what I've done in the past - that and these 3 tabs are about ready to come off the roof on their own with just a little wind. In the past I had use flat shovels and potato forks to then spend hours pulling nails. The shingle shovels have me kicking myself for not using them in the past.

 

[showcrop]

(quoted from post at 21:39:47 09/09/23) [b:40991cd51a]I would like a stuck down waterproof material under my shingles[/b:40991cd51a]

That is what I am thinking.
I can tie the studs to the floor and the rafters to the studs with hurricane ties (do not understand why every house is not built using them) the roofing material is the most vulnerable part in a storm.
Even if you can keep the roof structure on the house once the shingles or metal is gone rain water can still do a lot of damage.

I am thinking metal roofing.
Under that 2x4's screwed into the rafters.
Under that a roofing material with foil on one side to reflect heat back up to the metal.

<img src=https://www.yesterdaystractors.com/cvphotos/cvphoto162880.jpg>

Under that a peal and stick ice and water membrane in the valleys and around the edge.
I do not need it for ice but it helps with water on these edge areas.

The foil backed underlayment is good enough nothing is needed under it but I am thinking of covering the entire roof with the peal and stick underlayment like will be used in the valleys.

My thinking is the foil backed underlayment is nailed down.
If the wind takes the metal off this underlayment will rip up letting water in.
On the other hand the OSB would have to come off for the peal and stick to come off.
For a few hundred dollars I can get the added protection against water if the metal does come off.

I have seen several houses that the metal roof comes off in a storm.
The wind gets under the overhanging edge of the metal a rips it off.
I plan to put gutters around the edge to try and protect against this.

I just do not know if covering the entire roof with a non breathable ice and water dam will cause other problems so I ask the question here.

I wouldn't use steel unless it were the steel shingles or standing seam. The standard steel roof gets too leaky after 15-30 years. the holes get enlarged by the daily expansion contraction and the O-rings under the screw heads deteriorate. fiberglass shingles last much longer.

 

[Frank(Mi.)]

As a retired carpenter I have used the ice/water sheild on many roofs in the past. If your attic space under it is vented well both top and bottom there should be no problem. In a humid location like yours probably is, mold could be an issue. Maybe check with your building supplies store and see if they have any good info.

 

[DanielW]

Most steel manufacturers now recommend installing the screws on the flats right next to the ribs instead of on the ribs themselves to prevent that issue of screw holes enlarging. Even when screwed on the ridge, however, I've only seen that issue of holes enlarging on old, old barns with the
lead-shielded nails or the old-style of sealing washers, and old-style profiles. For many years now, steel profiles have been such that the expansion/contraction is taken up in the body between the ribs and thus the holes don't enlarge due to expansion/contraction. I have steel on 4 barns,
two machine sheds, and two houses (plus a couple of smaller fuel sheds etc.). The newest one is still 32 years old and shows no signs of leaking. The only one that has leaked is the oldest barn, with an old, 'wave' profile and the old-style of screws with the lousy sealing washers (the old
style didn't have the cupped washer over the rubber to sinch it down around the hole.