Neighbors of mine are moving, and the buyer hired an inspection done. One of the things the inspector mentioned was that the closed-cut valley should be tarred. I put on this roof in 2004, so i crawled up to look it over. The architectural shingles are all well-adhered to one another, and it’s not very easy at all to lift up the cut side of the valley.
Pitch is 5:12 and i took into account local wind patterns for which side got cut for bonus points. Valleys are underlaid with I&W Shield under a 36″-wide layer of roll roofing. (No metal though, sorry.) I cut my valleys a bit shy of the CL to help them flush. I’m self-taught, though, so i’m willing to learn better ways.
I read Guertin’s article about four ways to cut a valley, and he uses tar on the closed cut, but i’ve been wondering if that’s a good idea, when you stop and consider it. Is it for wind lift? It seems like you’d not get much lift in a valley. If it’s to try to keep water from shooting off one plane to the other side, i doubt it will work 100%, and afterward any water that DID get behind the tar caulking would have a harder time getting back out.
I’m not adverse to doing the work before the new owners show up Saturday, just not sure it’s the right thing to do, regardless of what the inspector said. Can you folks hash this out in public for me?
Replies
splintie,
Here in western Oregon (read rain country) I have never seen tar applied to a cut valley , nor for that matter metal valley under the shingles.
Even Ice and Water isn't used , double layer of felt, run the one side high , lap the overlaying side to near center and cut.
By the time the cut valley is going to leak the roof needs replacing here.
I had to repair rot at a lot of roof intersections on this one that were flashed badly, so that's why the overkill. With snow, we get a bit more abrasion than with only rain and i've seen cheaper shingles wear through at the crease. I've never had a roof leak in six houses so far, though i haven't always used the extra layer of roll roofing on the last two. The inspector didn't get all excited about it (not like the missing drip tube for the T&P valve on the water heater! <G>)The valleys aren't very long...a pic of the job (looks less than 5:12 from here now...hmmmm):
O.K. where to start? Here in Colorado (we do get snow) a cut valley is fine. On high altitude apps or north sides I&W shield is a no brainer. On top of that An 18 in and 36 in sandwich of 90 lb. to finish the valley. Then run the roof. There is NO need to glue a valley if properly installed. If the roofing inspecters are the same type we have...they don't understand the basic laws of physics. There is apparently no profesional standard for roof inspectors in Colo. Also home inspectors are unregulated..."For just 19.95 you to can inspect a home" Hope it is better in MT. Good luck, you are right and the inspector is wrong IMHO.
TWO layers of roll roofing, eh? I'm guessing that's so the toboggans don't wear through? <G>Thanks, i needed a snow man to chime in re normal practices.
I have no help for you, but....
I've half heartedly meant to ask here on BT what the reason is for the roofing cement in a cut valley.
To hold 'em down or to keep the water out?
I know that when I encounter a cut valley that does not have the cut side tarred down, the first thing I wonder is "what else did the roofer do/not do??
I am impressed that the inspector went on to the roof and checked the valley out.
Rich Beckman
You are here.
"I am impressed that the inspector went on to the roof and checked the valley out."He opened every crank on every window, too, so after today i'm qualified to replace operators on Anderson casements, too. A couple days ago, i replaced the chimney cap, another first for me. I'm getting to learn all kinds of new stuff on their nickel!Here's hoping we get a vote on the tar/no tar issue to satisfy both our curiosities.
In Florida, we always sealed the edge of the metal with 4" of plastic roof cement to prevent water from backing up too deep. Some would laugh at that idea, but they have never been in a torrential downpour like that. I have been in a car with a good inch of water standing on the hood because it was raining so hard it could not run off fast enough. The new raindrops falling into the sheet of water were even wearing diving suits and snorkels!
;)They have even made it code there now to seal wall flashings and valleys.
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Well, here's my opinion, from the "right" coast, snow country as well,.... no need to tar the valley, period. Tar is junk any way, IMHO. The rest of the assembly is fine as well,IMO....as to the I&W, I prefer and recommend Grace brand I&W, superior to others IMO. I don't like, nor will I ever use the granulated types.
Sounds like the inspector was trying to be very thorough, not bad, but we all learn something everyday in this biz, now you can help inform him, maybe even ask his reasoning for wanting the tar. Your "fears" of trapping water are good ones.
Splintie, good move cutting your valley up from the centerline... 2" is a good distance, allows for the wash of any debris down the valley...
Just my 2cents worth.
Geoff
Thanks, Geoff; i guess i feel pretty secure now about the lack of tar, but you've got me curious about the I&W shield. What's the problem with granules on I&W shield? I looked up the Grace website and don't recall the membrane i used having their name/logo plastered all over it as it appears there. I recall my membrane had a very fine layer of black granules, i figured to keep from slipping on it, but not nearly as coarse as roll roofing. I don't recall the brand, though; are there any to avoid? I have another neighbor who asked me last night at a potluck about doing her roof, so this info is timely.I think i measured less than 2" up from the valley, maybe an inch, but i'll remember that for next time. Those architectural shingles shed like crazy, eh?The inspector also suggested caulk around the skylight on his inspection report. I wondered, "Where?" LOL...
From what I've seen tar is used as a substitute for being totally sure of your skill level and knowledge of the task at hand.
None required if properly detailed!!
With asphalt shingles roofing cement is code in Florida. starter to eave, any flashings, all penetrations and any exposed nails. This plus six nails.
Yeah, you've got some of that Capital W wind down there.Wait a minute! Last time i was in Pensacola, it was all blue tarps! <G>
I hope you took someone with you when you left
What theslateman said. I've been roofing for 20+ years and I've never bought any tar.http://grantlogan.net/
Add me to the list of people who dno't put tar in valleys. I don't think I've ever once seen it done.
A good film is when the price of the dinner, the theatre admission and the babysitter were worth it. [Alfred Hitchcock]
If that inspector wants caulk around the skylight, he needs to go back to school! He could CAUSE a leak that way.
Ask him if he likes to see the weep holes in storms caulked in too!
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splinter---- I would point blank refuse to tar the valley
things might operate differently in other locales, but here in akron,ohio
1) shingles do not blow off in valleys, for the most part. On a gable roof any blow offs are likely to be within 3 feet of a main ridge on the main roof.
occasionally--- i see someone who has a shingle slipping down in a valley-----usually because that shingle was highnailed------and nailed with only 2 nails.
2)I feel VERY strongly tarring a valley will cause more leaks than it will solve in the long run------ I can't possibly stress this enough. water running down that valley----WILL get under the edge of the cut shingle---for an inch or so--------you will frequently find small leaves, maple "helicopters" etc. washed under there an inch or so.-----the water drains right out and down the valley
If you try to prevent that with tar-----you are simply going to direct that water sideway-----water running sideways has to travel a maximum of about 3 feet before it finds a joint between 2 shingles--LEAK----it's the sideways travel of water that will screw ya.
3) regaurding the grace ice and water shield--- it is fantastic stuff---if you can get it installed properly---without wrinkles. If you haven't used it-----you have NO idea how sticky it is-----just not describeable.-----and Grace refuses to install a truly workable split release sheet that would make the thing more installer friendly. working solo it is just about impossible to install it in a valley. certainteed makes a MUCH more user freindly product----granulated
to each his own----- If you NEED a granule free product----sometimes I use self adhering base sheet meant for the first ply of a self adhering modified bitumen roof.
good luck-----just say NO to tar.
stephen
As I mentioned above, there are places where the tar is a good thing. Roofs in Florida are often low pitch and can get great volumes of rain.But for her roof, I agree it is wrong to think of adding it there and now. Good point about the lack of wind damage at valleys. When I worked in Texas - where there is more big wind than most places in this country ( they think they invented wind in West Texas, but it is only an import from Montana and Wyoming) we would lay loose shingles and tools in a valley overnight and rarely, if ever, ever had any blow off
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I expected a bit more controversy, tar-lovers v. tar-haters, but the results are astonishing consistent. Breaktime first? <G>I did use a bucket of tar on that place, come to think, but it was only to fasten the step flashing in place on the deck w/o using nails. I also used a lot more nails than expected, too: at least half the sheets of ply had only 4-6 nails per sheet for the last 20 years. I don't see how you guys bid jobs, but i'm going T&M for all these jobs with a hidden component from now on.Thanks to everyone for getting back to me so soon on this. I'm sure the sellers will be as happy as i am that one more thing can be scratched off the inspector's list. The only remaining item to do today is to plane a door to fit better, then my job is done!
I'm surprised by the unanimity also. Especially since the instructions often say the cement should be applied.
Rich BeckmanYou are here.
I just got back from repairing a shed roof for some neighbors, one of those kind of sheds that are hauled in on a flatbed. There was tar for the caps, a sparse line down each side, but that didn't make up for the staples barely penetrating the sheating. I didnt't know you could get such short roofing staples. I'm guessing they're for attaching Tyvek or something...bizarre. And no felt, none at all. High nailed about half the time. It's a year old. I'm tearing it off and re-doing it on Thursday! <G>
Inspected a few houses.
Built a few houses.
Walked a few roofs for warranty claims.
Read a few manufacturer association installation specs.
Exposed Tar is not part of the spec for a properly shingled valley.
Concealed tar is for adhesive purposes, not watertightness.
Have the inspector/prospective owners check out the spec.
Your work is okay. Tar lines indicate a the presence of a problem.
Caulk requires regular inspection and maintenance.
FWIW.................Iron Helix
I roofed for over twenty years in several different regions, climate wise.
IMO< it is six of one and half a dozen of the other. sealing it when laying the shingles can prevent uplift and ice backups, but can also prevent water drainage if any gets in higher than the seal line. On point of installation, it is a matter of opinion one way or the other that I would never argue.
Now that it is done and not5 leaking though, one is far more likely to cause damage by doing it than by leaving it alone - a case of "If it ain't broke, don't fix it, or you might need to fix the fix"
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