FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Discussion Forum

Discussion Forum

15# or 30# felt for roofs?

| Posted in General Discussion on May 4, 2000 06:00am

*
Manufactures changed from 15lb. felt to “#15” felt about 4 or 5 years ago as they did with 30lb. to #30.
Full weight felts are still available and are known as ASTM rated felts. Although few lumberyards stock the ASTM stock many roofing suppliers/distributors do. Visqueen [polyethelene] sheeting is another product that isn’t full weight anymore but look what happened to the 5 cent candybar, too.

Reply
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Replies

  1. Frank_D | May 06, 2000 04:29am | #22

    *
    Here's one for you. A builder is putting up 4 houses on a 5 acre lot at the end of my street. These houses are selling for $700K and up (the agent is listing our house). Drove by today and the first house built and sold had portions of the vinyl siding removed. House is brick front and vinyl on the other three sides. Apparently, someone forgot the housewrap over the OSB before putting on the siding. What is going on here people??? Do the developers have the inspectors in their pockets??? I am appalled! I will be the GC on our new home. Trust, honesty and the american way, we're headed towards anarchy at this rate. Your comments appreciated. Frank

  2. Guest_ | May 06, 2000 05:21am | #23

    *
    Frank,

    Around here, and I assume most areas, housewrap is not a code issue. It is a specification item, and I hope to God we never get to the point that every construction decision is predetermined by code.

    As a homeowner, it is your duty to know what is in your house specs, and to choose a builder that you know you can trust. And having said that, keeping an eye on your project, so you can clear up any mistakes or misunderstandings, should they occur. Believe me, no inspector is there to see that you have a quality job and good value for your dollar. I've had some rough framing inspections last less than 5 minutes. (Not that I complained)

    I don't know what you do for a living, but you better think carefully before you decide to take on the second job of contractor. Do a search on this topic here and you will have some enlightening
    information on how risky that is.

    John

    1. Guest_ | May 06, 2000 06:15am | #24

      *Rich,Sorry I didn't notice your post 'til tonite. "Bull" is roofer slang for roof cement. The aluminum starter strip has to be tarred in to the felt, as well as soil stacks, flue pipes, chimneys, etc., before the shingles are applied. Instead of step flashing they use a piece of aluminum bent at a 90 deg. angle,4"-6" on either side of the bend, 8 to 10 ft. long. This is installed against the wall, and the horizontal leg (against the felt) must also be tarred in to the felt. The shingles are then installed over the horiz. flange and up against the verticle flange. Siding or counter flashing is then installed over the verticle flange.Hope I made myself clear, John

      1. Guest_ | May 06, 2000 06:26am | #25

        *Frank, where is your "HERE"? My "here" is Southern Calif. Four houses on a ONE acre lot is the norm, there are several such in-fill projects around town within the last year. In this area these are $300K to $450K range. There is no such thing as a 1 acre building lot in Orange County, hasn't been for a long time. No vinyl siding on those houses either. Joe H

        1. Guest_ | May 06, 2000 02:20pm | #26

          *CODE HERE REQUIRES 15# FELT UNLESS YOU GO FLATTER THEN 2.50/12 THEN YOU HAVE TO RUN TWO LAYERS OF 15# OR 1 LAYER OF 30. iF YOU GO FLATTER THEN 2/12 THEN YOU RUN ICE AND WATER SHIELD, THEN FELT THEN 3 TAB. that is if you want to run 3 tab that flat. I do not like running any flatter then 3/12. According to our local inspector , two layers of 15 is better then 1 roll of 30. Says it seals around nails better.

          1. Guest_ | May 08, 2000 02:33pm | #27

            *Yes, clear even to me.Thanks,Rich Beckman

  3. nick_kelly | May 10, 2000 03:31pm | #28

    *
    It has been said that paper punctured by thousands of nails is not exactly the best leak stopper. This is true. I've always heard that that the primary purpose of paper was to act as a moisture barrier to keep the moisture and oils in asphalt and asphalt/fiberglass shingles from leaching in to the roof sheathing and thereby prematurely aging the shingles,and that it was the job of the shingles to keep the water out.

  4. Guest_ | May 10, 2000 09:26pm | #29

    *
    A friend of mine recently went to a seminar put on my Owens Corning that focused on their roofing products. OC's recommendation was to use 15# builders felt rather than 30# for fiberglass/asphalt shingle underpayment as the 15# "breaths" better and the roof does not get as hot resulting in longer shingle life. That was the first time I'd heard that one… I like 30# for roofs that will be exposed quite a while before the roofing crew shows up.

    Any opinions?

    PS: My building supply still does not carry Roofers Select felt, but say that they are considering stocking it.

    1. Guest_ | May 04, 2000 01:33am | #1

      *Matt, IMHO #15 is almost worthless. I guess it's acceptable if you cover it immediatly with shingles, but as someone who remembers what #15 used to be(ragfelt base, not paper, and a weight that actually was 15 lbs.) what they sell now is junk. I have been using #30 as my normal spec. on roofs for about 11 yrs. now.John

      1. Guest_ | May 04, 2000 01:49am | #2

        *Matt,

        I'm a 30# man myself. My comments are the same as John's.

        View Image © 1999-2000"The city is not a concrete jungle, it is a human zoo." Charles Wadsworth

        1. Guest_ | May 04, 2000 02:57am | #3

          *Matt, Florida code calls for shingles to be placed on 15lb felt, but most builder use 30lb for the same reason you posted, to dry in until the roofers shingle. I've never had any problem with inspectors, but I have heard of an inspector with an attitude failing a contractor because "the code calls for 15lb"

          1. Guest_ | May 04, 2000 03:13am | #4

            *Wow! Thats like failing a rough-in for studs being 12" on center, instead of 16". Incomprehensible! Come to think of it, I have a good friend who roofed in Naples, and he tells me #30 is code down there, all drip edge must be bulled in as well as protrusions, before shingles are applied, and step flashig is not permitted, all because high winds can drive the rain under the shingles and up the step flash.John

          2. Guest_ | May 04, 2000 03:24am | #5

            *I've never used 15# felt under shingles... but have seen it under afew leaky tear off I've done. Perhaps a coincidence

          3. Guest_ | May 04, 2000 05:03am | #6

            *nothing wrong with 15# felt, especially on new construction..but for remodeling and tearoffs, we switched to 30# about ten years ago.. and stayed with it until Certainteed's Roofers Select came out.. now we use roofers select for everything that we would have used 15# or 30# for...

          4. Guest_ | May 04, 2000 05:42am | #7

            *JRS,If you could indulge me, please.> drip edge must be bulled in as well as protrusions, before shingles are applied, and step flashig is not permittedbulled in drip edge? protrusions? I know what drip edge is (the lumberyard here calls it starter), but after that I'm lost.step flashing is not permitted? So what is used in its place?Feeling ignorant (because I am),Rich Beckman

          5. Guest_ | May 04, 2000 05:53am | #8

            *You guys are rediculous to(o) often....So if they made 1000 pound would that be the way to go?????I have used 15 and none and and 30 and full ice and water shield....all with not a problemo...This discussion is like the one last year when there were several who said they used 3/4" ply for wall sheathing!!!!....Rediculous...waste of money...but if ya sleep betta at night...then to each his own...near the stream havin a hard time not bein mean...aj9

          6. Scott_Chadbourne | May 04, 2000 06:00am | #9

            *Manufactures changed from 15lb. felt to "#15" felt about 4 or 5 years ago as they did with 30lb. to #30.Full weight felts are still available and are known as ASTM rated felts. Although few lumberyards stock the ASTM stock many roofing suppliers/distributors do. Visqueen [polyethelene] sheeting is another product that isn't full weight anymore but look what happened to the 5 cent candybar, too.

          7. Guest_ | May 04, 2000 12:45pm | #10

            *I don't do alot of roofing but when I do, it's 30# if it's going to sit exposed for a few days, and 15# if I'm roofing it now. Never had a roof leak.We don't get florida's rain or buffalo's snow and by the time any hurricanes reach us, they've lost all their strengh tearing up the states below us.Why is 30# felt better? Does the 15 let water pass through it?, Will the 15, fall apart under the shingles when the 30# won't?

          8. Guest_ | May 04, 2000 01:45pm | #11

            *Jack, I use 30# because it stands up to the weather better than 15#. With our daily deluges followed by a baking tropical sun, the lighter weight paper just doesn't last. If my roofer dries in for me, he uses 15# and shingles over the same day. He likes it because it lays down with less wringles. It's my understanding that felt paper is used to separate shingles from the wood deck. If your'e depending on felt to stop leaks, get a new roofer.

          9. Guest_ | May 04, 2000 01:48pm | #12

            *I always use 30# felt, but then again, it never gets covered up right away on our jobs...I like it because it is less likely to tear when you are installing it, and lasts a lot longer in the elements. The criticism I remember hearing about felt the most is that it may become brittle over time. To me it seems like the thicker the felt and the more asphalt the better. Plus 30# makes great 1/16" shims for packing stuff out.

          10. Guest_ | May 04, 2000 03:14pm | #13

            *Maybe it's just because I'm a klutz and all, but every thime I've tried to walk in 15# on a steep roof, I've torn it somewhere. Guess what I use?Mike

          11. Guest_ | May 04, 2000 09:05pm | #14

            *Schedule shingle delivery on the last day of roof sheathing, and when you finish the sheathing you switch guns and start nailing down the shingles. If you expect rain and you put in the wood windows already, then felt it with whatever you can get till the rain stops and you can shingle. Put 6 guys up there and you can have 25 squares down in less than a day. I know some want to wait till the plumber gets his stack through but WHY? You can leave a few courses out for a chimney also. (ok , I know everybody wants to be (or hire) a specialist, get a roofer to do it. Carpenters are trained to roof yes?)

          12. Guest_ | May 05, 2000 12:32am | #15

            *Kind of intersting that when it comes to roofs you all recommend more than code requires but when it's sparky on the job, you want the code minimum. I can sympathize - since I also use 30# the times I have roofed - but it is a little wee bit inconsistent methinks. True, it doesn't add as much as say a switch from romex to emt, but it does add.

          13. Guest_ | May 05, 2000 03:41am | #16

            *and it's not a required code...i can chose 30 lb. or Roofer's Select as the need may arise.. or if it's new construction..15 lb....i am also not prevented by some arbitraray code from experimenting with new products...like Roofer's Select....

          14. Guest_ | May 05, 2000 04:00am | #17

            *A felt meeting some minimum standard isn't required by code? I always thought it was. In any case, certainly roofers select and 30# meet the same minimum perforemance tests that 15# must meet to carry that astm marking.

          15. Guest_ | May 05, 2000 04:23am | #18

            *geeesh bill ..yur a PITA.. where did u lern to read?the 30 # is not required by code , nor some arbitrary rule..i can use it IF i want.. unlike the rules yur discssin as MAY be adopted in yur willage..solve the mystery of the 7/11 stairwell in the 24' house yet?

          16. Guest_ | May 05, 2000 10:17pm | #19

            *To those that scoff at the use of felt paper under shingles:Do you know what "headlap" is? I doubt it. Headlap is the difference between twice the shingle exposure and the total height of the individual shingle.For example. A standard three tab shingle is 12" tall. It is normally laid at a 5" exposure. That leaves 7" of coverage by the next course(course #2). Right?...Wrong! The next course may cover by 7", but the keys(cut-outs that form the tabs) go up another 5". Plus, where the shingles butt together, is not continuously covered. So even keyless shingles have this weak link.The third course covers course #2 by 7" and course #1 by 2". This is the headlap. The weak link in the system is the headlap. If you have a driving rain the water only has to be blown uphill 2" to get under the shingles. On a 12/12 roof this is almost impossible. But on a 4/12 roof this is very likly to happen. Around here we call these roofs "Feltless Wonders". Felt under the shingles is the last line of defense against water.I get anywhere from 5 to 20 calls a year on leaks of this type. It depends on how long and severe our storm season is.So......I guess if you live where there is no rain and no wind then felt is truly unnecessary. For the rest of us, who have to answer to our customers years down the road, we do what we have to do.JohnP.S. I am not suggesting that EVERY roof without felt leaks, only that it unnecessarily increases your chances of a leak. And that's what good roofing practice is all about-minimizing the chances that a roof can leak.

          17. Guest_ | May 06, 2000 01:14am | #20

            *If 30# felt cost $5000 more than 15, everybody here would use 15. Especially since there is no local group with no real world knowledge of roofing passing rules because they think 30# might be better.

          18. Guest_ | May 06, 2000 03:14am | #21

            *JRS:The think about headlap is very interesting - I guess I'm easily entertained! :)By the way, here at Breaktime, someone brought up another advantage of felt which is supposedly that it prevents asphalt from the shingles from being absorbed into the roof sheathing and thereby drying out and shortening the life of the shingles. Don't know this for a fact, but it sounds plausible to me.

  5. Guest_ | May 10, 2000 09:26pm | #30

    *
    Josh,

    I agree with nick. No way does felt "seal around the nails"- #15 or #30, one layer or two. Ice & Water shield is the product you want to use for that purpose.

    John

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

Rescuing Old Hardware

Whether it’s already in your house or picked up at a flea market, vintage hardware almost always needs help.

Featured Video

Micro-Adjust Deck-Baluster Spacing for an Eye-Deceiving Layout

No math, no measuring—just a simple jig made from an elastic band is all you need to lay out a good-looking deck railing.

Related Stories

  • Ramon Martinez, Site Supervisor
  • What Size Nails?
  • Stop Ice Dams When Reroofing
  • Outdoor Lighting

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Fine Homebuilding Magazine

  • Issue 332 - July 2025
    • Custom Built-ins With Job-Site Tools
    • Fight House Fires Through Design
    • Making the Move to Multifamily
  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2024
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

Enjoy unlimited access to Fine Homebuilding. Join Now

Already a member? Log in

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data