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-   -   No felt under 25 year old three tabs! (http://www.diychatroom.com/f9/no-felt-under-25-year-old-three-tabs-118684/)

Ed G 09-29-2011 11:45 AM

No felt under 25 year old three tabs!
 
We recently had our roof redone and discovered that the original, 25 year-old three-tab roof didn't have any felt or ice/water guard underneath... just shingles nailed to the plywood! The valleys on 3 dormers had some sort of ice/water, but no metal. There were a couple areas stained from water penetration, but no significant damage... not even along the gutters that routinely grow icicles in winter.
BTW- The roof is a 9/12, about 40 squares on an otherwise well-built custom home.

Was this typical roofing practice just 25 years ago?

I thought it was a miracle we got 25+ years from the three-tabs (no missing shingles or major issues other than age), never mind the missing underlayment!

tinner666 09-29-2011 03:01 PM

UNderlay has only gotten important since they started making shingles they know aren't much good. They used to be pretty waterproof, now just water resistant and very thin.
If they were any good, no underlay would be needed, but being made by the shingle companies, it's a great upsell and adds to their bottom line too.

And I should mention that roofing is a trade occupied by many non-trades people with little roofing skills. I&W and felt will help mask a lot of sins. We roofers call it 'Dumbing down the trade' so anybody that can nail can call him/her-self a roofer.

Maintenance 6 09-29-2011 03:13 PM

After 30 some years, I've still not found somebody who can explain what a felt underlay does for a shingle roof. It certainly isn't a back up water proof layer. It's poked full of nail holes, so just what is it's purpose?

ParagonEx 09-29-2011 03:57 PM

Quote:

Originally Posted by Maintenance 6
After 30 some years, I've still not found somebody who can explain what a felt underlay does for a shingle roof. It certainly isn't a back up water proof layer. It's poked full of nail holes, so just what is it's purpose?

As a vapor barrier between the condensation in your attic and your shingles.

www.paragonexteriors.com

Roofmaster417 09-29-2011 04:57 PM

Quote:

Originally Posted by ParagonEx (Post 738430)
As a vapor barrier between the condensation in your attic and your shingles.

Agreed.,.,I have torn off single layers with no felt as well as multiple layers with no felt.Steep and walkers.

I was informed years ago that the sole purpose of felt was as Paragon explained about the elements and moisture also because of tree sap deteriorating the shingles.

I have also been told and have noticed that the steeper the roofs the lack of and the necessity for felt is needed.But with felt not being an expensive part of the roof system then why not use it.

Ed G 09-29-2011 06:24 PM

Quote:

Originally Posted by tinner666 (Post 738410)
UNderlay has only gotten important since they started making shingles they know aren't much good. They used to be pretty waterproof, now just water resistant and very thin.

Now that makes sense to me. I saw 3-tab and assumed lower quality, when in fact they were probably better quality than their replacements.

Roofmaster417 09-29-2011 07:02 PM

Quote:

Originally Posted by Ed G (Post 738514)
Now that makes sense to me. I saw 3-tab and assumed lower quality, when in fact they were probably better quality than their replacements.


Absolutely.,Sad thing about it is the shingles attached directly to the roof deck with multiple layers on top when removed are thicker and sometimes more sturdy than most of the limited lifetimes of today.

Slyfox 10-01-2011 07:12 AM

Felt/Underlayments serve a multitude of purposes.

1. Temporary dry in to keep the sheathing out of direct exposure to the weather until the roof can be installed.

2. Prevent heat & moisture escaping from the interior of the roof from damaging the under side of the shingles.

3. Prevent shingles from sealing to the roof sheathing.

4. Help minimise water penetration in storm or coastal area situations.

5. Prevent ice 'formed in gutters, bottom of valleys, etc.' from pushing melted water up & under the shingles from penetrating the roof sheathing.

It was not the thickness of shingles in the old days that gave them so much more longevity then today's, it was the asbestos.
Even non-asbestos shingles had plys of felt inside them that were called rag felts.
Rag felts had small amounts of asbestos in them.

Just because you find moisture in between the shingles and felt doe's not mean shingles aren't water proof.
A shingle roof is a breathing roofing system, that moisture is from wind driven rains and condensation situations and sometimes poor workmanship.
They are as water proof today as they were in the old days.

MJW 10-01-2011 08:37 AM

Pretty sure the OSB is more of a vapor barrier than the felt.

bcdemon 10-01-2011 09:24 AM

Quote:

Originally Posted by MJW (Post 739439)
Pretty sure the OSB is more of a vapor barrier than the felt.

:eek:
Why use a product that will absorb moisture as a vapor barrier?

I have only seen a few old roofs that have any sort of underlayment. And it's usually a 36" strip of poly along the eve, if anything at all. So to answer your question, yes it is normal to NOT have any underlay on an old roof.

I think most companies consider the felt as a wind blown rain stopper. It's not going to stop a consistent leak, but it will prevent a minor amount of water from penetrating into your house.

Slyfox 10-01-2011 11:34 AM

Quote:

Originally Posted by MJW (Post 739439)
Pretty sure the OSB is more of a vapor barrier than the felt.

Never thought of sheathing as a vapor barrier being it has opened/un-sealed joints. The opened joints allow heat to escape and with out an underlayment that escaping heat will hit the underside of the shingle, which normally is not designed to resist heat.
The felt isn't a vapor barrier in a shingle installation, a vapor barrier isn't needed in that type of breathable system.

Slyfox 10-01-2011 11:46 AM

Quote:

Originally Posted by bcdemon (Post 739460)
:eek:
Why use a product that will absorb moisture as a vapor barrier?

I have only seen a few old roofs that have any sort of underlayment. And it's usually a 36" strip of poly along the eve, if anything at all. So to answer your question, yes it is normal to NOT have any underlay on an old roof.

I think most companies consider the felt as a wind blown rain stopper. It's not going to stop a consistent leak, but it will prevent a minor amount of water from penetrating into your house.


I did a re-roof earlier this year that had two layers of shingles on it, top was Owens Corning 25 year 3-tabs installed in 1990, the bottom was a (not sure of brand) 3-tab with the ripples in the tabs, I think they were Certainteed and it was installed in 1955/56.
The original roofers ran a half course of felt across all eaves and up all rakes, nothing in the valleys and that is common for that era.

The re-roofs I have done in which the homes were built in the mid 1960's or newer, finding no underlayment is very rare.

MJW 10-01-2011 02:24 PM

Quote:

Originally Posted by Slyfox (Post 739526)
Never thought of sheathing as a vapor barrier being it has opened/un-sealed joints. The opened joints allow heat to escape and with out an underlayment that escaping heat will hit the underside of the shingle, which normally is not designed to resist heat.
The felt isn't a vapor barrier in a shingle installation, a vapor barrier isn't needed in that type of breathable system.

I agree mostly. The felt has plenty of open ends also. :wink:
The heat should go up and out the vents, but I get what you're saying. I have seen shingles adhered to the sheathing because there was no felt under them.

Very rare to see a roof without felt up here. Plenty without anything on the walls though.

Back when the framers were actually carpenters, on a new house they would "dry in" the house with felt until the roofers got there or they roofed it themselves. Just a few years ago they would put up the house wrap also, but not anymore.....well, who builds new anymore....

bubbler 10-01-2011 02:37 PM

Quote:

Originally Posted by Slyfox (Post 739531)
I did a re-roof earlier this year that had two layers of shingles on it, top was Owens Corning 25 year 3-tabs installed in 1990, the bottom was a (not sure of brand) 3-tab with the ripples in the tabs, I think they were Certainteed and it was installed in 1955/56.
The original roofers ran a half course of felt across all eaves and up all rakes, nothing in the valleys and that is common for that era.

The re-roofs I have done in which the homes were built in the mid 1960's or newer, finding no underlayment is very rare.

My house was built in 1950, 2nd layer of shingles applied in 1992. The original owners sold it to me, said the 1992 roof was the first they did. I found moderately significant water damage inside the walls where a dormer meets, I'm guessing must have been happening just prior to the re-roofing. Still, 42 years from the original roof... now on nearly 20 years for the replacement roof.

I have the unhappy duty of being the one to pay to have everything stripped and re-done. Whether it's a crutch or not I know I'll be asking the roofer to quote me at least 6-8' of I&W to gain an edge over ice dams that happy frequently here.

ParagonEx 10-01-2011 05:25 PM

Quote:

Originally Posted by bubbler

My house was built in 1950, 2nd layer of shingles applied in 1992. The original owners sold it to me, said the 1992 roof was the first they did. I found moderately significant water damage inside the walls where a dormer meets, I'm guessing must have been happening just prior to the re-roofing. Still, 42 years from the original roof... now on nearly 20 years for the replacement roof.

I have the unhappy duty of being the one to pay to have everything stripped and re-done. Whether it's a crutch or not I know I'll be asking the roofer to quote me at least 6-8' of I&W to gain an edge over ice dams that happy frequently here.

Ice & Water shield does not prevent ice damming.


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