Roofing underlayment - roofing felt requirement questions & answers:

Frequently-asked questions about the need for felt underlayment below asphalt shingles or other roof coverings.

This article series discusses roofing felt, specifically addressing the roofing code or roofing manufacturer's requirements for use of an underlayment, such as roofing felt, tarpaper, or other underlayment products beneath asphalt shingles and other roofing materials.

Roofing Felt / Underlayment Requirement FAQs

[Click to enlarge any image]

Our photo (page top) shows felt underlayment in good condition as a worn out roof was being stripped. It looks as if the installer of asphalt roof shingles (still visible at below right but now worn out) may have placed roofing felt on top of a still older wood-shingle roof.

Questions & answers about the requirements for roofing underlayment posted originally

at ROOFING FELT UNDERLAYMENT REQUIREMENTS

On 2019-11-06 by danjoefriedman (mod) - no ice and water felt or a double layer of felt under the asphault shingles

Hmm a little confusing

"ice and water felt" is not a product that exists; the roofer probably meant no "ice and water shield" or waterproof membrane that is often used in leak-prone areas (roof eaves, valleys etc) in new roofing; That is a great product though not required by building codes.

similarly

"water felt or a double layer of felt" doesn't quite compute; double layer of felt is not required under an asphalt shingle roof, but indeed to comply with asphalt shingle installation guidelines from most manufacturers a roofer would be expected to use a layer of roofing felt - as discussed above on this page.

The roofer can see the roof construction by looking carefully at roof gable ends or eaves, often lifting the shingles carefully (hopefully without damaging anything).

My overall opinion is that the part of the roof report you cite is not useful nor meaningful.

You don't give the important roof questions and answers for a home buyer:

1. Is the roof leaking anywhere? If so where, why, how extensive, cost to cure, etc.

2. What is the remaining roof life - approximately - in years? Any specific observations that mean reduced roof life (not properly vented, not properly nailed, etc.)

3. Is there roof damage or are there roof errors or omissions likely to give trouble or leaks such as improper or missing flashing at valleys or roof-wall abutments, chimneys, etc. ?

A buyer needs to know if she' facing

- a near term significant re-roof expense
- risk of hidden damage from leaks

On 2019-11-06 by Anonymous

A roofing contractor, who inspected my roof for a potential buyer states "it appears that there is no ice and water felt or a double layer of felt under the asphault shingles". Short of peeling off shingles how would he know that? The roof was installed by a professional roofing company, prior to my purchase, and there is not and has not been a single leak, and not a single shingle has peeled or cupped, and there is no moisture damage.

On 2019-10-21 - by (mod) -

I don't see a problem as long as they will adhere to ome another at overlaps. so if I missed a concern or question please let me know.

On 2019-10-21 by Anonymous

Is it permissible to use two different brands or kinds of peel and stick underlayment on my roof?

On 2019-09-20 - by (mod) -

Sounds as if there are ice dam backup leaks - but I'd need to know more about roof construction and to see the actual leak point to understand the situation.

Most-likely the roof isn't properly installed and you will need to remove enough roofing to permit installation of enough ice and water shield underlayment to prevent future leaks.

It might also be possible to correct under-roof ventilation to avoid ice formation.

See HEAT TAPES & CABLES for ROOF ICE DAMS https://inspectapedia.com/ventilation/Roof_Gutter_De-Icing_Cables.php

and see ROOF ICE DAM DIAGNOSIS https://inspectapedia.com/ventilation/Roof_Ice_Dam_Leak_Diagnosis.php

On 2019-09-19 by Dominic joseph

I have a 1.3 pitch valley and it only leaks in the winter when ice is formed. never leaks in summer, its a new roof on addition tied into existing structure. leaked 1st winter only when ice formed, when ice melts leaks stops. ice was in the 1.3 grade valley.

On 2018-02-16 - by (mod) -

Jeff,

UNDERLAYMENT REQUIREMENTS on ROOFS - https://inspectapedia.com/roof/Roofing_Underlayment_Requirements.php
describes your situation and states:

Asphalt shingles can be used on roofs with a slope of 2:12 to 4:12 if double-coverage underlayment is used.

You can install multiple layers of shingles and underlayment without doing a tear-off, depending on code restrictions where you live and on the number of layers already in place.

Details are at ASPHALT SHINGLE RE-ROOF GUIDE https://inspectapedia.com/BestPractices/Asphalt_Shingle_Re_Roof.php

Typically on a conventional roof you'll be allowed 2 layers, or in some jurisdictions 3.

But Watch out: on a mobile home whose roof is most-likely not framed to the strength of a conventionally framed home, the weight of added roof layers could cause a structural problem.

Low Slope is defined as slopes from 2:12 to 4:12

I would advise against squeaking-by "the letter of the law" on roof slope vs shingle application method, as if you push by just 1/4" of slope you're asking for a leaky roof and future complaints, claims, hassle that's not right and not worth-it.

Instead I'd have used documentation of having done a more-reliable roofing job as a selling point.

Also see LOW SLOPE ROOFING https://inspectapedia.com/roof/Low_Slope_Roofing.php

On 2018-02-15 by Jeff Lester

I recently "flipped" a single wide mobile in WA state. I had to have an L&I inspection and he is throwing the book at me in regards to permits. He is stating that I need 2 layers of 15 # felt vs 1 layer of 30 # on a 4:12 pitch roof asphalt shingles. I called a local roofing company and of course they are saying he is correct. My question is do I have to tear off the entire roof, or can I put rolled roofing over the existing or remedy this issue any other way? The inspector said this rule actually written on the back of a bundle.I haven't verified that it is a 4:12 roof I think it may be like 4.25:12 but I won't know until I put a tape on it

On 2017-11-07 by (mod) - bad roof job, leaking, where do I get an inspector

I would start by focusing on identifying what needs to be fixed on the roof and having those problems corrected as quickly as possible in order to avoid expensive damage to the building.

In the experts directory at the top of any of our Pages you may find a home inspector who is able to help you.

On 2017-11-06 by carole brinkert

New roof installed, an have had nothing but leaks, no drip edge either...water is wicking up into the roof!! Were can l get an inspector or do l need a lawyer too?

On 2017-11-06 by (mod) - how many layers of felt were actually installed under the shingles?

Tom,

A detailed answer to your question about determining whether or not the roofer used single or double felt underlayment is given at

UNDERLAYMENT DOUBLE vs SINGLE

On 2017-11-06 by Tom

I have a doublewide mobile (low slope) that the contractor says he put double felt on. I was not on site that day. Roof is now coverded in 30 year composite shingle. The city inspector says it's single layer of felt.

With flashing all around the edge of the roof I'm wondering where he's looking? Contractor is standing by his statement. How do I tell?

On 2017-05-13 by (mod) - is it common for a roof to leak before shingles are installed?

Steve,

It depends. If the roofer simply installed felt, sure it's possible to see some leaks: the felt is not a waterproof roof covering since it is punctured by nails all over the place.

Where ice and water shield is installed, such as is often used at roof eaves and at valleys or other flashed locations, that membrane should seal around nails and shouldn't leak.

On 2017-05-13 by Steve

New home construction. The roofing felt paper was just applied and I noticed several leaks after a rain storm around the valleys and one or two other locations. Is it common for leaks prior to the shingles being installed?

On 2017-03-27 by android said:

Pretty good post. I just stumbled upon your blog and wanted to say that I have really enyed reading your blog posts. Any way I'll be subscribing to your feed and I hope you post again soon

On 2016-09-16 by Keith S

Thanks for the information.

On 2016-09-16 by (mod) - Does roofing felt serve any purpose on an open structure like a gazebo or pavilion?

Sure, Keith; if there is a solid roof deck below most roofing products, the roofing manufacturer wants underlayment installed; you're not just protecting against leaks - I infer you're suggesting it doesn't matter if a gazebo roof leaks onto the lovers trysting below - it's also protecting the roof decking and framing against water damage, rot, insect damage that would ensue.

On 2016-09-15 by Keith S

Does roofing felt serve any purpose on an open structure like a gazebo or pavilion?

On 2016-08-19 by (mod) - is 30# felt required on roofs?

Aug

Depending on the roof covering material, climate, and other factors, Local codes may specify 30# felt underlayment, though 15# is common too. You'll want to find the roofing code for the country, state, province where you live.

Un-stated is what's the issue here? If the roof is leaking the issue isn't the underlayment.

On 2016-08-18 by Augustino Brothers

We are in a dispute and NEED your HELP!!! We were taught that on a roof that is 7/12 or greater...that 30# felt or a really good synthetic passes code requirements??? Could you please verify and advise...
Thanx you,

Robert Perdomo

On 2016-06-21 by (mod) - old clothes and rags ?

Roof underlayment is not a useful place to even think about disposing of old clothes.

Typically volunteer organizations such as the Salvation Army or Red Cross accept clothes donations and sort through them. Items that are not suitable for use by others are then baled and sold as rag-scrap to raise a little money for the association. Or you can take that route directly.

On 2016-06-21 by ANNA MUSGRAVE

looking for place to get rid of old clothes and rags this is from a mission to help buy food for food pantry

On 2016-03-21 by (mod) - large fir tree branch fall and break (13) tiles on my roof.

Paul,

I can't quite offer an authoritative citation as I don't know where your property is located, what codes apply nor exactly what sort of tile roof is installed.

"Meets code" is a mis-used and mis-applied claim and approach to good building practices. Building codes are a minimum standard. At the end of the day, your roof needs to meet the roofing manufacturer's installation specifications. If you insist on relying on "meets code" as basis for an argument, then you need to find, in your local, state, or provincial building codes, the code section that says (as most codes do) that the product must be installed following the maunfacturer's specifications.

Some tile roofs absolutely rely on the underlayment to prevent leaks, where the tiles themselves offer only sun protection for the underlayment and of course an aesthetic roof topping. Such roofs are common in the South and Southwestern U.S. (for example).

Other tile roof systems rely on the tile design and installation to shed water effectively, using the underlayment as a surface padding, as leak protection during installation. Such roofs are found in Norway, northern Europe, and in the Northern U.S. such as in Minnesota. You'll find photos of all of those tile roof examples here at InspectApedia.com

If you know the specific roofing tile product, we (or you) can find its manufacturer, then find the manufacturer's roofing tile installation specifications. That will put an end to the arguing and finger-pointing.

Paul, also see our excerpt from Best Construction Practices (Bliss) at CLAY TILE ROOF SLOPE, DECK & UNDERLAY - https://inspectapedia.com/BestPractices/Clay_Tile_Roof_Slope_Deck_Underlayment.php

where we will re-post your question, our detailed reply, and any further references we can dig up.

On 2016-03-21 by Paul Smyth

Two weeks ago I had a large fir tree branch fall and break (13) tiles on my roof. The roof let water fall all of the way to our Hardwood.

When we asked the contractor about installing under all the tiles, to meet code. They said they only had to put tar paper around where the tiles were broken. Is the contractor right?

When the hole was open we could see that none of the tiles had no underlayment. We could see the sky!! Please call me @623-249-3549 or send an e-mail. Please refer me if you can not provide the answer Thanks

On 2015-12-12 by (mod) - My contractor cut my felt paper short and it does not reach the edges

J

If the roof is installed this is a dispute you don't want to have since the cost of re-roofing over a dispute over felt details is costly for both parties and unlikely to be satisfying. To re-roof over again to fix felt is prohibitive in most views.

Look at the roof shingle life warranted by the manufacturer. Detail exactly what felt installation defects are present. Ask the manufacturer for advice on accepting or correcting that or ask how those defects affect the shingle warranty.

Let me know what you're told.

On 2015-12-11 by J

I understand what Nov 28 Anon said. My contractor cut my felt paper short and it does not reach the edges, much less go passed half inch which I wanted. Now what do I do?

On 2015-11-29 by (mod) - Roof Contract states the felt paper does not need to be even with the roof deck edge/drip edge.

Not sure exactly what you mean. Best practice laps the felt over the top of the drip edge, but of felt edge is nor precisely even work the drip edge outer edge - the edge projecting past the lower edge of roof shearhing, that's ok

On 2015-11-29 by Anonymous

I had a new roof installed and the Roof Contract states the felt paper does not need to be even with the roof deck edge/drip edge. Is the contract correct?

Question: did omission of felt underlayment contribute to shingle blow-off in windy conditions?

(Aug 18, 2011) mike callahan,lake erie roof&sid said:

I have encountered a roof with absolutely no felt in what way did this contribute to the seal of the roofing if any? Shingles are blowing off constantly! The roof was installed in 1998

Reply:

Mike, the article ROOFING FELT UNDERLAYMENT REQUIREMENTS quotes authoritative sources on why we want felt below asphalt shingles on a roof. But I haven not found any reference to a connection between shingle blow-off and the absence of felt. If shingles are blowing off of a roof it's most likely because

- the self-sealing tabs did not seal
- the shingles were not properly nailed
- the roof is exposed to particularly high winds

On the other hand, the omission of felt underlayment may increase the roof leaks that occur during a storm when shingles blow off of the roof.

Question: using heavier than 15# felt

(Dec 12, 2011) Jon Wright said:

Are there any OSHA, IRC, NRCA or other regulations about using stronger than 15 lb. felt on steeper roofs to protect the installer?

Reply:

15# felt is the minimum recommended felt thickness. Other specifications are in the

article ROOFING FELT UNDERLAYMENT REQUIREMENTS

Question:

[delete] (Aug 16, 2012) Anonymous said:

My name is Dennis from Deco roofing systems ltd.
I am looking for a board which is between 10-12mm thick to be used as an under layer material for the Shingles.
Mostly what we use is silvachip board which is a recycled material from tetrapak.

Kindly advice on whether we can get a material which can be nailed on the roof and if possible it should be waterproof.
We are considering importing several containers for our running projects.
Looking forward to hearing from you soon.

Regards

Dennis
+254722588467

Question:

(Oct 12, 2012) Mike said:

can you install new felt over the old felt? what negative effect can it have?

Reply:

Mike -

No particular problem except if you leave a mess or old half-driven nails or old rippled, torn or folded felt you may have a rough surface that punctures new felt and shingles or causes the new roof not to lie flat. One needs to make a field decision based on the on-roof conditions.

Question: hail damage in McAllen TX

(Nov 19, 2012) Maria form Cancun said:

I live in McALlen Tx. In april, we had a historic hail strom. My 2 rental houses' roofs were replaced by a cheating Roofing Company. Contract said: 25 Owens Corning, but he installed Tamko 20year; and all wrinkled.

Now he wants to offer me what the original contract said: Ownes Corning 25 years. My question is: 1500 shingles x 5 nails each one = 7500 extra holes the plywood will have. I do not like the idea of having a strainer as a roof. I want this cheating roofer to install new plywood as punishment for being a thief.

Pleas,e help me with yor answers. Maria from Cancun

Reply:

Maria,

It is common to install three or even more shingle roofs atop the original roof sheathing without worrying that the sheating has been damaged by prior nails.

Just be sure that the OLD roofing is first removed. Mulit-layered shingles on a roof often have a shorter life. ALso that will allow an actual inspection of the roof decking or sheathing - any rotted or damaged sections should be replaced.

See also HAIL DAMAGED ROOFS

Question: originally a shake roof, now a concrete tile roof.

(Feb 6, 2013) Anonymous said:

I inspected a home today that was originally a shake roof, now a concrete tile roof. The structure is reinforced 2X6 so I am not as concerned about the weight, as I am the underlayment.

I found the roof had metal hat channel screwed to the skip sheathing and a heavy paper, almost cardboard type underlayment between the hat channel and concrete. I saw no battens supporting the tiles and all the fastener at the ridge and valleys were exposed screws. Has anyone seen anything like this? The roof was installed in 2004

Question: We just started manufacturing roofing underlayment in india

(Apr 12, 2014) Jonathan said:

We just started manufacturing roofing underlayment in india and we are trying to find dealers on north America who can market this product.
Please advice or comment over how to go ahead or can some one be bridge between us and end users.

Question: insulating & venting a cathedral ceiling

(July 1, 2014) Anonymous said:

Would it be safe/wise to insulate a cathedral ceiling with, say, styofoam/then sheeting, then asphalt shingles from the outside and how would you vent the heat out of the interior - gable end vents? I'd prefer not to insulate from the inside. I'd like to keep the look of the interior cathedral boarding (3.5" fir).

Reply:

Anon

I've installed a design that placed foam insulating board atop rafters, followed by plywood, then roofing; we left an air space between the plywood deck underside and the top of insulation placed between the rafters in an effort to obtain a very high-R roof.

It seemed to me to have been a waste to place that uppermost layer of foam insulating board. However there has been more recent research on the effects of and benefits of heat transmission through top-insulated roofs.

If you don't want to disturb the interior finished ceiling you indeed have to insulate from above. Some approaches include

- installing insulated strutural panels onto the rafters or over an existing roof deck (after tearing off old roofing) - making either a hot roof design or using insulating panels that inclde a vent path from eaves to ridge vent

- tearing off decking, insulating between rafters - foam or fiberglass - leaving (or not) an air path (hot roof or not)

- Nailing high-R solid foam atop rafters (or existing bare decking) then plywood, then roofing, venting the rafter space from eaves to ridge

See specifications at

• CAPE COD ROOF & KNEE WALL INSULATION & VENTILATION
• CATHEDRAL CEILING INSULATION
• CATHEDRAL CEILING INSULATION FAQs
• CATHEDRAL CEILING INSULATION FAQs-2
• CATHEDRAL CEILING VENTILATION

Question: who is responsible for step flashing caulking when a new roof has been installed?

(July 8, 2014) greg o said:

hi. who is responsible for step flashing caulking when a new roof has been installed? thanks

Reply:

Greg,

In my opinion the caulking of the upper edge of step flashing, if the design requires that sealant use, is certainly part of installing the step flashing itself, not a separate job. Usually roof flashing installation is part of roof installation, though there could be exceptions such as when a roof penetration is installed *after* the roof has been installed.

Then proper flashing should be part of the installation of whatever that subsequent thing was - a chimney, plumbing vent, etc. If the installer does not know how to install flashing then s/he needs to arrange with a qualified roofer or other person who knows how to install flashing - else the job will leak and thus have been improperly executed.

Question: remove existing flashing to install ice and water shield properly

(Oct 24, 2014) Leslie said:

I am having my roof re-shingled and I am worried about my skylights. I asked the roofer if we should install ice & shield around my skylights but he said it's not necessary as he doesn't think it's a good idea to remove the skylight flashing.

He said the ice & shield goes under the flashing and he's reluctant to replace the current skylight flashing since it is not leaking. Is this true or is he just trying to avoid extra work? Other roofers I received quotes from said I should install ice&shield and new flashing around skylights.

Reply:

He's got a point that it is difficult to install ice and water shield under existing flashing. He' d have to remove and reinstall the flashing to do a good job. That's what I'd prefer.

Question: felt underlayment on concrete tile roofs?

(Mar 29, 2015) Sam S. said:

My house has a concrete tile roof where the tiles were nailed directly to the spaced sawn wood stripping that is nailed to the roof rafters. There was no felt underlayment used and no deck to apply it to. This roof is now 36-years old and has never leaked, at all. Would felt underlayment improve this assembly and how would it be installed?

Reply:

Sam you don't say where you live - as concrete roof tile installation requirements or specs vary by jurisdiction.

At any event, there is no cost-reasonable way to add felt below the existing concrete tile roof. Leave it alone and bring this up again at re-roof time - if we live that long.

Question: is tar paper required by building codes?

(May 9, 2015) Debbie Cleland said:
I need to know if tar paper is a must under the building code...My roof was reshingled in 2008 and this year had a leak...the roofer who fixed leak said there is no tar paper under my shingles..Is this against the code...can the contractor be fined and made to bring my roof up to code? I live in Elliot Lake Ontario canada

Reply:

Roofing manufacturers recommend using roof underlayment. It does not have to be specifically "tar paper" as other products are also available.

If your local building codes require following the manufacturer's installation instructions then underlayment is probably requried where you live.

Question: installing new shingles direct on plywood?

(June 19, 2015) Norma said:
We moved into a home in a newer subdivision (10 yrs. old). When we bought the house 4 years ago that would have made the shingles/roof 6 years old. We, along with several other neighbours are now faced with having to re-shingle our roofs. Some quotes from a variety of roofers are saying we don't need a membrane under the new shingles. We feel the current problem we are all having is because there is NO underlay or membrane on the roofs.

We live in a cold/hot climate in Canada and because of those types of weather conditions (which are sometimes very very severe) we feel the membrane is necessary. Some owners have decided to go ahead and apply new shingles to just the plywood. Is this a good choice?

Reply:

I would

1. follow the shingle manufacturer's recommendations to install underlyament

2. in freezing climates like Canada I'd like to see liberal use of ice and water shield at eaves, valleys, and other leak-prone areas.

...

Continue reading at ROOFING FELT UNDERLAYMENT REQUIREMENTS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Roofing Underlayment-related Articles

• ROOFING FELT UNDERLAYMENT REQUIREMENTS - home
  • ASPHALT SHINGLE VALLEY FLASHING
  • CLAY TILE ROOF SLOPE, DECK & UNDERLAY
  • ROOF VENTILATION SPECIFICATIONS
  • ROOFING UNDERLAYMENT BEST PRACTICES
  • STANDARDS for ROOFING
  • UNDERLAYMENT DOUBLE vs SINGLE
  • WARRANTIES for ROOF SHINGLES
  • WOOD ROOF SHEATHING, UNDERLAYMENT
• STANDARDS for ROOFING

Suggested citation for this web page

ROOFING FELT UNDERLAYMENT REQUIREMENT FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING ROOFING

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