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When roofers don’t felt under shingles, I wonder what impact that has on getting the shindles off the roof 20 (optimistically) years later. It seems the shingles would melt themselves to the plywood or OSB over time.
Any experienced roofers have an answer to this?
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Replies
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When roofers don't felt under shingles, I wonder what impact that has on getting the shindles off the roof 20 (optimistically) years later. It seems the shingles would melt themselves to the plywood or OSB over time.
Any experienced roofers have an answer to this?
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Kevin, asphaltic felt underlayment is the only way we apply roofing. New work, old work, heated, unheated... no matter. The argument against it is: Felt breeds rot.
Bull Pucky!
It's true, you CAN find
rotted sheathing under felt... after you get the remaining 20 year shingles off.
Ask: When was this roof put on? "Oh, when we bought the place,
just before our first child was born." Do the math, the kid's 28 now... the shingles were 20 year... hmmm.
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Read the instructions on the bundle of shingles ....I think you will find that most brands recomend felt underlayment ..... if you install the shingles according to the manufacturer's specs ,and have a warranty claim, I think you will have a lot fewer hassles getting an adjustment.
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Kevin...felt serves 3 purposes. 1) Keeps building dry during construction before shingles. 2) Acts as a backup if shingles fail..and 3) prevents a chemical reaction caused by the glues in the plywood and the asphalt in the shingles. I pulled this info from a roofing back I have. Later!
*The primary benefit of felt is as a quick dry-in in new construction.Once the roofers cut out all the wrinkles caused by exposing the felt to rain and dew for a couple of weeks and then shingle over it(300- plus nail punctures per square) it will have virtually no water repellancy value.As far as preventing the shingles from glueing themselvesto the deck ,over time , I don't see this as a big concern either.Over the last 15 years I have only encountered this ONCE.(lucky it was only a garage).It is far more common for me to find the FELT has glued itself down to the wood.(Ever unrolled a piece of felt and found wet patches of asphalt saturation?)The next question is do I use it?On customers jobs ALWAYS.I have found that this seems to be the one thing homeowners will single out to determine if the contractor does "quality work".Personally,I think they would be better off looking at how he flashes chimneys etc.( Does he even own a sheet metal brake? Can He use it?Is he willing to use a little Ice Gaurd to be extra sure?) I did use felt on my own home because it was a long drawn out affair,but I left it off a new garage/shop we put up last year-and I won't be laying awake at night worrying about it either.Funny thing is I eliminated the felt but then I went and over vented the roof.(what the heck,why not do it my way on my own place?) Good Luck, Stephen
*Gentlemen. For many years the NAHB has been trying to get the code required felt underlayment stricken from the codes.Stephen add to your list of questions the home owner should be asking of a roofer, "Tell me how you nail the shingles. Do you nail into or above the glue line? Do you install protective flashing on the rakes ends? Given that 95 percent of all roofing shingles are incorrectly installed, and therefor more prone to wind uplift, felt makes good sense/cents.In my book--sorry Gabe--Complete Building Construction I urge roofers to use only felt that complies with ASTM(American Society of Testing & Materials)D4869 and ASTM D226. GeneL
*The rot you're finding is from the use of fiberglasspolyventism-icedamiing&undersheathingcondensationism...not the extra eight years...J
*Gene,shingle instructions that are never read by 99% of roofers says to b nail below the glue line.In all the roof inspections I have done, never have I seen it done according to instructions except when our crew does the job....J
*Fred,Weatherization includes roofing and it sounds like I agree with you and your roof advice to...Keep getting the message out,J
*Ditto "below" the glue line, at least for CertainTeed. This is illustrated at their Web site (www.certainteed.com) in the installation section. I frequently advise folks to get the instructions for the shingles they'll be having installed in advance and attach them to the bid request and include language in the contract that the shingles will be "installed in strict accordance with (brand name)'s current written installation instructions" (exact CertainTeed warranty language). Doesn't guarantee it, of course, but it could help a workmanship claim.As for felt, the same insructions say, "Shingle underlayment is suggested(ASTM D4869 Type I)."
*I think you all know that I wouldn't put felt under the shingles! If you think the felt is going to help you keep water out, why would you pay so much for ice and water shield? Just use felt!I am intrigued, but not convinced about some of the statements. The one that holds the higest possibility, is that the ply sucks the life out of the shingles. What puzzles me, is why the sucking power stops at the felt?Please convince me, as I plan to re-roof my house arter my planned addition.Blue
*Do you put felt on over old shingles for a re-roof?Blue
*What causes the downward cupping of the tabs?Does upward cupping occur only on felted roofs?I always thought the shingles were the drainage plain.I agree, driving rain can penetrate the shingles, but where does the rain go, when it gets trapped between the shingles and the felt?Blue
*Maybe this chemical reaction is what is causing some of the others to fall through the osb. Maybe some osb has a wrong chemical for roof underlayment.I thought felt was a same petroleum product as shingles. Wouldn't that cause the same chemical reaction?Blue
*Jack,You beat me to it. I was just planning to reply to Gene with that observation.The last shingles I installed were quite explicit to nail below the glue line.I LOVE instructions.Rich Beckman
*I do not reroof over old shingles If and when we roof it is over sheathing only.
*I think most roofers would prefer to nail below the glue line.If the shingle manufacturers would consistently place the glue line on the same height on the shingle this would be MUCH easier.Problem is, this glue line varies in location by as much as an inch or more from bundle to bundle and the width of the line itself varies quite a bit also.Then when you factor in the height you need to nail ABOVE the keys but below the glue line, it can sometimes be nearly impossible to comply with wrapper instructions. The important thing is to make sure that your nail hits the headlap of the shingle below. When you nail so high that you miss the headlap you ARE asking for a blow-off.(as an aside I will point out that an article in FH a few years ago, written by a roofing company,openly admidted that they rarely nailed below the glue line.I think tauton sells a roofing how-to book by this same company).Since I am going to be the one who has to handle the call-back in event of a blow off,(never had one yet,knock on wood)I will determine where I feel comfortable nailing.We use 4 nails in every 3-tab,sometimes6in dimensionals.We put extra wide drip edge around the entire perimeter of the roof and always felt the customers deck( even though we feel felt is of very minimal value--- the customers want it).AS far as voiding the manufacturers warranty by varying the nailing pattern ,I am sure you vary the recommended spacing when you shingle around valley flashing ,chimneys,soil stacks,roof vents etc.If varying the nailing pattern voids the warranty you have already voided it.I have never had to try to collect on a shingle warranty( again knock on wood) and I know of NO ONE who has succesfully collected on one.The directions on the wrapper are excellent instructions for roofing 90% of most roof areas but it is the other 10% of the roof which causes the most problems.( and on these areas the wrapper offers no help.)Only experience will help you with a blind valley draining directly against a wall, or a entire 24 foot garage run that drains directly against a wall, or a chimney or waste stack directly in a valley, or an eyebrow window. The wrapper doesn't know every thing, but it can give some people a false sense of competence.Remember, everything seems easy when you safe on the ground or writing about it on a computer, but it is MY money and safety that is on the line on every roof we do. Good Luck, Stephen
*A relative is in the materials business, sells a lot of roofing,seldom has to make good on a claim. Why? Because lots of roofers staple when the instructions say nail. When they nail they do it in the wrong place. If they have a situation that isn't covered in the instructions they don't ask what to do.Put me in the "love those instructions" category.
*Fred B,I could be wrong here but I don't think any wrappers forbid staples.The term they use is fasteners.Some even show 2 pictures( after all most of us roofers are illiterate) 1 picture depicts a staple installation , the other picture shows a nail installation.Again, I could be wrong because it has been quite some time since I felt so unsure of my abilities that I had to depend on a shingle wrapper for how to advice. You are correct if you are assuming that nails provide a vastly superior installation. Good Luck, Stephen
*Nails are superior, but staples will do the trick if the installer pays attention to the depth that staple is driven.Staples are also good for dragon flies!Blue
*I staple my roofs and I have had one claim against a manufacturer...They gave me 25 square of shingles and $1000 for my labor back in 1988...Staples are allowed by some companies if not all.J
*BoogermanDragonflies b EATmosquito's!!! Realizing, of course, that no self respecting Mosquito would venture near the 'motor city', you wouldn't have any use for these wunnerful critters. . .shoo em across the river, blow 'em down my way. . . package em up and bring em to the slap fest!!!snow's-a-meltin'. . . bugs are on the way!!!-Patrick
*Patrick,Last year for whatever reason we had hardly a bug around here except in the fall; millions of lady bugs knockin on all the doors and windows...Be nice to see another year like last.Boogerin without bugs,J
*Gentlemen. the turpentine in the plywood resins dissolves the asphalt.Ninety-nine percent of all sahingles are nailed into or above the glue line.I onece had a roofing contractor tkae issue with me when I stopped him fromnailing inot the glue line. He argued the the shingle wrapper would show that he was right and i was wrong.I told him if I was wronmg i would admit it and leave him and all the other roofers alone.I asked for a wrapper and handing to me he said see for yourself. I was nearly knocked to the ground when I saw what appeared to be that he was right. Then i noticed that we were looking at the wrapper up side down. This is no made up joke. It really happened.Another problem with roofers is their failure to nail corrosion resistant flashing--drip-edge to the rake ends. According to those who earn their living repairing roofs, 99 percent of roof failures begins at the unprotected rake ends.GeneL.
*Well I can't speak with a great deal of authority because most of the roofs I put on are metal. But I am quoting my relative correctly. Also, a couple jobs this past summer I noticed the roofers were stapling. When I asked they said they liked it better even though the manufacturer specified nails...And it was faster and cheaper.Oh yes, back to the original question: I've put on roofs both with and without felt. Can't say I can give a good analytical reason why to or not to use felt except that sometimes it seems to give a better seal around the screws/nails and prevents a leak. It is cheap and if it only does that occasionally the installation is worth it.
*Gene,Go to Home Depot when you get a chance and read the label on the shingles....Nails go below glue line...But it doesn't matter that much as I have seen nails all over the place and no leaks....Sorry Gene...99% below,J
*JackThei "for whatever reason"is all the "nuclear fallout" dropping on you from the Ohio valley. LOL-P
*Gene, if the turp dissolves the asphalt, why would the manufacturers specify asphalt impregnated parper? This whole issue is makingless and less sense?The question of nailing below,aor above the tar strip is really a misguided discussion. All of the shingle wrappers that I have read, indicate that the fasteners must be installed below the tar strips. They don't specify why, but carpenter sense will tell you why! ED NOTE: Blue has specifically said "carpenter sense", because common sense is not allowed to be used anymore due to legal and liability issues.The importance of the nailing has been properly noted by one of the more astute members of the boogerin' club already. The fastener must hit the underlying shingle. If you nail abovet the top of the underlying shingle, significant damage will be done to the top shingle as the fastener is driven tight. The shingle companies tell to put the fasteners here, or there, but they don't consistently put their tar strips in the proper place. Sometimes the strip is so low, that your fasteners would be exposed, unless you adjusted your reveal, or simply nailed into or above the tar strip. The tar strip function will perform either way. A tiny bit of nail, or staple isn't going to significantly affect the sealing performance! Sometimes that tar strip is very high, and if yu do nail above it, you will be forced to nail above the underlying shingle, thus voiding the warranty. All of this is in sharp contrast to the proper nailing lap siding. The nails must be installed above the underlying siding, when installing wood siding. This effectively pulls the top portion of the siding tight to the sheathing. Maybe some on this board are confusing the two applications?Blue
*Patrick,The Lady bugs do look like "nuclear enhanced" creatures..J
*When nailing with a coil nailer, if you consistently nail below the glue line,the contact nose of the gun will become rapidly gunked and "hesitant" because even though the nail is in the "right" place the gun is in the glue line.ELK shingles, which I use at every possible opportunity, are a laminated shingle and the glue line is on the bottom of the back of the shingle.Seal down strip protection, and, clean guns. Why aren't all shingles made this way? Good Luck , Stephen
*Blue, old shingles? The carting companies know me on a first name basis. Anyway, if we didn't rip the old ones off, what would the newbies do after toting up the bundles?Total tear off. Evaluate the sheathing. New Felt, bituthane, flashing. Copper valley and lead at the chimney, galvy nails (except on the copper). Architecturals if I can, rather than 3-tab.
*Ah... another satified ELK customer!
*Jack and blue eyed devil/ Jack Yes beloe the glue line, But not because it has anything to do with leaks.The issue of were to nail is a matter of the shibhgle's wind resistance. As one gets higher up the shingle the leas the shibgle's wind resistance and the more the shinple is exposed to wind uplift. Alas I must remind you. No matter how wrong the shingle manufacturers are they hold the ace card.Yet I wonder how many shingle warranties have been voided because of incorrect nailing? GeneL
*Shingles....I have very little trouble with using them....I have no clue how they could generate such a long discussion...Elk's sound great...what an easy solution to tool gum up!!!...Wish I held that patent!J
*I agree, that's the way to go. I'm just glad I don't have to do it anymire.
*Gene, A substantial portion of my income is from roof repairs and rake edge drip has never been an issue.I find that valleys and chimney flashing are the trouble spots.In high wind area's I could see the rakes being a problem though
*I saw a TOH segment once that showed how shingles were made. One constant was that the shingle was never turned over, something that I'd think would be required in order to put the glue strip on the back. I presume that the ELK shingle is more expensive than standard shingles, both due to the extra process and the heavier shingle.
*I would tend to agree Stephen.Blue
*Stephen, blue eyed et al. First. Turpentine in the plywood's resins dissolving the asphalt is less of a problem today--according to CertainTeed--than it was years ago. In fact I don't remember ever hearing of it happening while I've been in business.Second. The turpetine caused the shingles to bubble and led to the shingle's eventual destruction. But why, you ask doesn't it happen to the asphalt impregnated underlayment? It does but to a lesser extent. The underlayment in this case is a sacraficial layer to protect the shingle, so any damage to the underlayment is susually minor. Therefore we sacrifice the underlayment to protect the shingle.Third. As already noted by me, where the nails are located is important. The higher up the shingle the nail is located the less of the shingle is held down: its wind resistance is lessened.Fourth. ARMA (Asphalt Roofing Manufacturers Association) strongly argues for nails vs. staples. It may have already have said no staples. As you know they are not allowed in Dade county, Florida. GeneL.
*And you think I'm going to believe Gabe? His poly theory lowered his theoretical value, and he cant explain why ice makes things expand, and why heat makes things expand!Blue
*Hi Fred,Your comment about the volitiles is one that I had never thought of. Makes sense.I usually follow the method in George's post. I have seen some relly old roofs still in good shape with no felt. They were ALL with steep pitches. I have only done one roof without felt or ice and water shield. It was on a shed in my back yard with a 15 in 12 pitch. I don't think wind will blow rain under the shingles with that pitch.Ron
*Rich,I read the instruction too. I dont allways follow them, but only after thinking about the effects.
*I'll stretch this thread a little bit, but I tried staples on cedar wall shingles. Darned if they didn't hold better than the nails. Still feel funny about using staples on fiberglass shingle in a windy area thou.
*Gene, I just don't buy the turp theory, and the "lesser extent" comment. Are you saying that with all the tecnological wisdom, roofing companies couldn't come up with a 100% sure buffer between the ply and the shingles?Blue
*I thought of an obvious question yesterday.If shingles curl down because of volitiles being sucked into the wood,how come I find so many 2nd and 3rd layer roofs with turned down shingles. If a thin layer of felt is a sacrificial layer to protect the first layer of shingles, would not the 1st and 2nd layer of shingles protect the 3rd layer.( and before anyone reams me a new one let me say I don't install 3rd layers,but I have torn many off)With all due respectto those greater minds out there........ Strong Back,Weak Mind...Stephen
*Perhaps the desiccated lower areas remove volatiles from the new layer?So what makes (new) shingles curl UP?
*Curling has more to do with expansion and contraction, unequally on the top, and bottom of the shingle. Maybe heat differential has an effect.Who cares! If the dang things didnt curl, you'd never have a re roof job!Blue
*BLUE, you are a frigging GENIUS.I have been coming at this from the wrong end. I should be marketing with planned obsolesence in mind,like the Auto companies(warrantied for 3 years or 300 rainfalls,which ever comes first)Anybody have any suggestions on which shingles fall apart the fastest?I feel there is a market here just waiting to be filled.Good Luck,Stephen
*SteveI was told ELK shingles have granules on both sides. If this is true have you noticed this having any effect on thier curling.
*Don't ask. . . he no longer wants to know!!!
*
Kevin;
Here's something everyone else missed: O-C requires underlayment to meet UL Class A fire rating. Do the other manufactureres specify this?
Other than for the fire rating it is not required.
I too prefer using paper over the deck. It is very inexpensive extra isurance on leaks
b if installed properly.
The only negative I have to say "D@#$ that stuff is slippery on a dew laden roof."
We worry the details of flashing the rake, valley, crickets around chimneys and against sided walls then we go & use those cheap electro-galvanized roofing nails. I prefer the good old multi bath hot dipped.
Cheers; JE
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Kevin,Good question.We haven't seen an Elk shingle with granules on both sides for some time now.Except the rediculously expensive hip and ridge cap.
Good Luck,Stephen
*blue eyed. As we all know turpentine if produced from pine resin. Asphalt shingle manufacturers are the source of the "turpentine dissolves the asphalt." Fact or theory, the fact remains, as JohnE noted, that O/C--and perhaps all shingle manufacturers-requires the felt underlayment if the shingles are claimed to be UL Class A. That is, it is the system of shingles and underlayment that is firerated. GeneL.
*Still sounds like gibberish to me Gene! I went up and checked out my paperless barn roof and feel quite confident that it won't be leaking soon!Paper away all tar paper freaks!Still goin' bare,Blue
*I started asking the "with all the nails and bubble reducing knife cuts in this felt paper what the heck is it for?" question the first roof I worked on in the early 70s, and I have been asking it ever since. It made for interesting if somewhat redundant discussions and I never did get an answer I thought made much sense until last year. A retired cedar salesman told me it was a left over practice from the days when shingles were mostly asphalt. The sheathing would wick the oil out of the shingles and they wouldn"t resist water as well. With today's fiberglass shingles I sure wonder about the practicality of it.The same rational goes for cedar roofs, the sheathing would wick the resins (oils that give cedar its weatherability) and the cedar would get dry, porous and brittle.The thing he told me that really got my attention was this - have you ever stripped a roof or siding and seen how blackened some of the sheathing was, while other parts of the same building the sheathing still looked woodlike? The blackened areas are where this protection failed for one reason or another. I sure have seen a lot of what he described.Another thing he told me of interest was the reason all the old barns here in the Pacific NW have shakes on them is as late as 1960 compsition roofing was still 17-18.00 per square, hand split heavy shakes were 10-12.00!
*Young Bob, it still doesn't make sense. If the sheathing can wick asphalt impregnated materials, why wouldn't they require a different type of barrier?In our sub, the building inspector has warned the roofers about laying the tar paper vertically. Does the sheathing wick asphalt through vertically layed paper?This tar paper business is silly! Its a throwback to the days when cedar shingles were layed over spaced boards. The rain would penetrate the shingles, until they swelled up. Since small amounts of rain could enter the attic, during the swelling periioad, they layed the paper as a barrier.When asphalt shingles were introduced, they didn't have a seal down feature. Since they could easily be lifted during a driving rain, paper was still needed. With the new seal down shingles, paper is not needed. Period! All the stories that tell you that roofs fail are hocus pocus! The shingle manufacturers are staying with the recommendation, because there is no unified voice telling them to stop the needless practice. The day will come though.If shingle manufacturers required a self sealing paper, it would make sense. If you think tar paper will seal a houlse, punch 1000 holes in a sheet, and drape the thing on your couch. Then pour five gallons of water on it, and don't worry, the paper will keep the water out!Silly!Blue
*Blue.I'm with you I don't understand the sense of it all either.However I still install tarpaper under the roofs that I do because my clients think it makes a better job. So as long as it makes me look better than the other guys, and the clients want to pay for the stuff and for me to put it on I'll continue using it. After all it can't do any damage having the tarpaper under the shingles. Also some shingle manufacturing reps have told me that the warranty may be void without the tarpaper. However I haven't seen anything in writing yet to confirm this. I just don't want to take any chances.By the way I hate installing shingles. I just haven't been able to find a roofer that can install the damn things staight.
*I know what's eatin' ya Blue, you're sore cause you can't use an 8 pounder to fasten the stuff with. Booger on Ragae Blue!
*It would work fine, as long as you didn't put shingles over it. The shingles trap the water, and it ends up leaking through the paper. If the paper was truly water proof, they wouldn't require Ice and water shield which claims to self seal the nail holes. I haven't seen anyone claiming that TP self seals it's nail holes. Are you claiming they do?Blue
*Blue - let's go back to the anti-wicking idea for just a second. I think you are discounting this for reasons you state in you first sentence, what if back in the 20's, 30's whenever this became the norm, asphalt impregnated products were the most impermeable barriers they had? or at least they got acceptable results within economic constraints using them.Don't get me wrong, I have long had serious doubts about paper with modern shingles. I just think that at one time, with the forrunners of what we use today, it might have been a usefull technique.As for waterproofing I totally agree.
*
I installed dozens of roofs on homes and barns during the early 80s using no felt underlayment. I still drive by many of these jobs now 15 years later and they all look as good as the day I laid them. In areas with the possibility of ice damming I'd use a felt or rubberized underlayment along the rake.
*I guess I can confess to not installing my roofs as to the instructions on the bundle.. I can read them but I do not agree with them. I have never in my 22 years experience ever cut the tabs off my starter course to bring the glue line down to the first course. My thinking is that those tabs have more benefit helping to prevent ice damming, I flip mine over tabs uphill for starter. Also a glue line past the overhang will prevent the shingle from curling in towards the gutter as I believe it should. It will act as a lamination and hold the shingle out straight in plane with the roof. I DO however use felt and ice shield. Also I use eave starter and project my roof out 1 inch beyond the rake.
*
Woodchip,I am with you on this one(an other controversy).I never cut the tabs off.Out of the hundreds of roofs I have torn off I have seen tabs cut off exactly ONCE.It was memorable because I had never seen it before and have never seen it since.
I have however found a lot of roofs done by people who have great faith in wrapper instructions.I can always tell these roofs because the installer took seriously the instruction to turn the starter course upside down.Thats when I find the starter shingles laid granule side DOWN.When I find these I know I will be billing for wood replacement elsewhere on the roof.
Good Luck,Stephen
*That's how I do it too mark.Blue
*I tried it once. I'll try anything once. I don't quite agree with your assertion that a tar strip near the bottom will automatically prevent curl.I think that a tar strip up about two inches from the eave would bear the same benefits that all the subsequent tar strips deliver: prevent uplift.I just don't worry enough about it to do it!Blue
*
I was wondering what the common practice is out there
I have always installed #15 or #30 felt under my shingles and yet I have found some who seem to think that, in unheated structures (garages), this is not necesary: What are your experiences/opinions??
*Kevin, so do we.It's a very, very minor line of added defence against water infiltration but I will continue to do so. It's cheap and easy to do.