3 Tab valley question: Am I right?

Did a roof for another company last week. He just lost his crew and was in a bad pickle. Anyway, it was a trailer house with a 2/12 pitch with a front gable that was a little over a 3/12 pitch. I went ahead and added ice and water in the valley from my truck eventhough he didn’t purchase any. Since the pitch of the gable was higher, my guys went ahead and crossed the gable facet over the main roof section and cut the valley.

Company owner gets on roof and blows a gasket! He claims the valley was done wrong. At first, I look at it and believe him. My crew chief comes over and explains that the gable has a steeper pitch so he intentionally crossed the gable side on top. Company owner is adamant that the larger side always goes on top because more water drains from the larger side. I explain that I believed he was incorrect but added that we did install ice and water shield and that we cross our shingles about 2 feet past the center line. I offer to redo the valley his way but he refuses. He then complains that he didn’t want a California valley. I explain to him that this is a closed cut 3 tab valley and not a California which is what we sometimes do on 30 year roofs.

As a side note, I can say my Crew Leader has around 1,000 roofs under his belt with zero call backs. He’s pretty rare. The same guy I clocked at 60+ squares a day last year in new construction. Was my Crew leader right or the other guy? I have actually heard it both ways.

It’s a general rule that the steeper pitched deck is the cut side of a closed valley system. However there are exceptions to every rule and imo a signifigantly larger deck would be one of them, particularly if the pitch change was only and inch as you suggested.

Id have to agree with Tar Monkey.

Pitch is usually the determining factor in what slope is more dominate. but 1 inch in slope doesn’t make much of a difference. The larger deck area should of been the dominate slope.

How ever, if the valley was installed correctly in combination of using ice & water shield… I doubt there will be any problems.

If the pitch difference is minimal, then I would then look at height difference.

This is one of those instances where you have to be there to decide.
But I’m thinking I would have done the little gable/dormer first then the main roof.

Big side should have been cut in this one…2/12 & 3/12 is not really a pitch difference…

Agree with all responses. Whole thing should have Ice/water shield as well. At minimum, gable and eves and valleys, if cost an issue as well as dweebed courses to shorten exposure.

Some gratitude he was showing you.Blowing a gasket on a trailer house is poor self control.IMO of course.

I have helped other contractors out and have never had problems but I would not stand for someone showing their a** when I was doing them a favor.

First and foremost I believe my crew leaders over anyone on any day.Its called trust.They are in the position of “Leader” for that reason.If I cannot trust them to have a valley installed correctly due to pitch then I have failed.

Valley installations are the same,major over minor. Major pitch over minor pitch,major slope over minor slope.Someone that has 1,000 house under his belt should know how to install a valley.

You should always take your crew leaders side until you find out otherwise.It creates a bond between both of you.You are showing faith in his installations.Escpecially in front of another contractor.

But if you don’t have faith in his installations then,well thats another story.

ditto monkey.
sorry but your guy needs a little steeper/bigger dormer to be rite.
fire em.
just kiddin.


no wonder your not a boss…I&W the whole thing?? :lol:

On a trailer roof? I can’t imagine there being much roof above the gable. It’ll work

2/12 pitch shouldn’t of had shingles on it anyway according to the manufactures specificiations and standard roofing practices. However the 1/12 pitch difference on double wide really wont make a diffrence either way you installed it, extra insurance with the Ice & Water in it will resolve any issues of the right/wrong installation

Another thing to consider besides pitch is field area
and which surface is going to carry more water.

GAF and Certainteed don’t mind if you shingle a 2/12, you just have double up on your underlay or use I&W in order to obtain warranty. Most companies are like this actually. Except IKO, if you shingle a 2/12 they only warrant their 30 yr shingles for 12 yrs…

I would never install an archictectual shingle on a 2/12 pitch, it wont work that roof will be leaking bad in 6 years guaranteed !!!As soon as the nails rust out it will start leaking laminates trap water and it will travel to the nail head and leak,seen it many times on center match decking that is cupped on 4/12 and aove decks.I can install an exposed fastner metal roofing system on low slope for the same price as an archictect and never have issues with leaks.My customers would bad mouth if i did crap like that, roofs are to expensive and my reputation is to important to do bum jobs!

Manufactures are not going to warranty thier shingles on a 2/12 pitch, its a labor issue.Installer error to low of a pitch for shingle to be installed not the manufactures fault.


no wonder your not a boss…I&W the whole thing?? :lol:[/quote]

ABSOLUTELY Ice and water the whole thing. This is a project manager/salesman saying this, too! Anything under 4/12 should be all I&W. especially with 3-tabs. You’ve got a possible water infiltration spot every 12 inches with a dip (puddle) right behind the overlap. 4/12 and up water with flow off. Below that, water sits and spreads (ice too)

How many years have you had as a roofing mechanic, nwronk?

I’ve been in roofing 5 years now. Various trades for 6 years before that in both civilian and military

To clarify, what I meant is: so I know how much cost it adds to the job, and I know it’s a harder sell, but IMO and many manufacturers’ opinions, it is well worth it.

The point here is that shingles are not waterproof, they are made to shed water, and if they don’t have enough pitch to do so, water will get into the system (that’s why a dotted sealant strip is more advantageous than a solid sealant strip, so water can exit) In areas where you have more likelihood for water to enter the system, you would be ahead to put I&W down to keep it from getting in the building. In this scenario, the area is the entire roof.

ahh…no in this scenario it should not even have shingles…