Integrating new shingles with old + metal flashing Q's

I was ready to ask some metal valley detailing Q’s when I was hit by a curve ball yesterday: Metric vs. English/standard (12 x 36) shingles.

I haven’t needed a roof in 25+ yrs. However the covered walkway between house & garage, particularly where it intersects the 5/12 roof on the house wasn’t detailed, nor flashed properly. I found soft decking around the intersection area and a couple of holes.

So I tore it all off to have a look, and have done a lot of detailed carpentry work to fix rotted trim pieces in addition to replace the 1/2" ply deck. Went back with P&S in the three 5’ valleys, 5" width strips to cover the ply edge at the eave and metal 2x2 drip w/ kick around the eaves. I’m also installing metal V-channel in the valleys.

So far, so good.

About the time I’m ready to put new shingles on, I discover the new ones I bought (only 2 sqrs for this area) are not 12x36, but 13-1/4 x 39-3/8! Furthermore, the roofing supplier I obtained these from no longer carries any 12x36 shingles…period! So I called another…no joy.

I’d planned on nesting new shingles over the old. Obviously that’s not going to work here. I don’t want to bridge them either. It was suggested I lay 30# over the old and shingle over them. Or tear them off. Or return what I have and scout for 12x36’s.

Evidently the roofing world changed while I was busy doing other things! Metric shingles?? My layout guides/books are now (long) obsolete! Obviously this isn’t news to you pros. And many, if not most, wouldn’t even bother with a shingle-over, lay-over, or whatever you want to call it. Particularly when you have to warranty it.

I found a shingle I like, in the color I like and having to trim every one doesn’t appeal to me. Neither does tearing off the old roof, in the Tx Summer.

So for those that do layovers, what other options are there for using a larger metric shingle over a smaller english one?

why would it matter? i’ve layed over t-locs and no problems…other then it was a … should i say it? … a layover…

Metrics blend into standards just fine, just shorten the exposure.

Aren’t TAMKO’s still standard size?

Tamkos by me are still standard.
Ax is right you can just shorter the exposure. You will go through a little more material though. About 15%.
Ive done layovers before where I just pop a line and go. Don’t worry about nesting. It works fine, just looks a little bumpy.

You can “tie in” metrics to standard shingles as they are (obviously) larger, you just need to cheat the exposure. You can not however do the opposite.

Unless his old shings are 3 tab standards & he is trying to match up using 3 tab metrics. I read it a couple times trying to see if he had 3 tabs or archs & I didnt see anything that indicated either?

Thanks for the replies. Been raining off & on the past week so I’ve been working on other things. The existing shingles are 3T 12x36 with a 5" standard exposure. The new ones are CT Landmark’s dimensional 13-1/4 x 38-5/8, also with a 5" exposure, which was a surprise as I thought the ‘wider’ shingle would have a greater exposure. Perhaps this is to maintain continuity with the old 5" standard? Whatever.

So the new shingle is 1-1/4" 'wider" top to bottom. With a 5" exposure, that means 8-1/4" of it is not exposed (compared to the 7" for the old shingle).

In CT’s app. manual from their website, I read “Roof-over methods for metric dim and Landmark TL shingles: The same methods used for clean-deck application of these shingles are used for roof-overs. ***Application of these shingles OVER english dim shingles is not recommended – due to the high cost of workmanship & greater risk of worker error.***”

So what exactly is CT referring to re: “high cost of workmanship & greater risk of worker error?”

are you tieing in from bottom of old shingles? or tieing in on rows?

Laying over 3-tab without nesting is fine if thats your only option. If you are stressing over it just tear it off, its only 2 squares you said.

The covered walkway between the garage and house is what I’ve been working on. From above, it looks like a “L” each leg about 10’ long. One end butts into the garage wall, the other into a 5/12 roof on the house.

The new shingles will meet the old roof at the two valleys formed at the intersection. I was concerned about tying into these with the new shingles once I discovered they’re different sizes. A photo will help illustrate, not sure how to post one though.

Been reading up more on nesting vs. bridging. Also temporarily put some new shingles up on the old roof, nested them and took some measurements.

What’s clear (at least where I measured) is that the roofers ‘stretched’ the shingle exposure…sometime to 5-3/8". Other places it’s 4-3/4". Guess they didn’t snap chalk-lines. If consistently applied, then this allowed them to use fewer squares. Nice…

Note: The walkway I tore off is about 2 sqrs. The rest of the roof is about 25 sqrs.

As mentioned previously, the valleys where the covered walkway intersected the roof on the house were where the leaks & rotted decking occured. This area had to be ripped off and repaired to fix it correctly. I wasn’t about to lay new shingles over it.

Just put a W valley metal in and leave as a open valley, no tieing in then…

This is one of the areas I’ll have to tie the new, larger shingles into. Since the new CT Lndmrk’s are to be installed with a 5" reveal, it does simplify things somewhat. I can vary it a bit to make it all line up.

This is the left valley viewed from the ladder. It spills onto a tiny section of the main roof. I P&S’d all of it to ensure water would run off.

the valley on the left side should be installed lower and a couple step flashings under the valley metal where lower roof and dormer roof connect…and on one of my roofs you would be short a lenght of valley metal…not enough coverage on ridge or the bottom…just sayin… :wink:

I haven’t applied the metal valley yet. I needed to do some thinking before taking the snips to it and screwing it up! It WILL completely cover the valley though, past the bottom edge of the ‘upper’ roof and hang over 1/2" or so.

Because CT mixed ‘english’ with ‘metric’ on the same instruction page, I caught a mistake of mine: english are used with 5" exposure, however metric are to use a 5-5/8" exposure.

If I try to shorten a bigger metric shingle to 5" to make it nest into the existing english shingle 3T layout, the new shingle won’t completely seal across it’s length: Part of the tar strip will be ‘flying in air’ in a gap. This is quite noticeable from the ground on my 5/12 pitch. It may also void any warranty. Instead of 100% of the shingle edge adhearing, now only ~ 50% would.

Others have replied that some dim shingles are still avail in english, BUT getting them locally is the problem. The three shingle suppliers I called said they don’t carry english shingles anymore. I did find english 3T’s at the box stores though. . perhaps that’s to distinguish ‘amateur’ from ‘pro’.

Not good. . . . nor acceptable. And trimming 5/8" off of 26 sqrs would be a PITA. Good thing I decided to think this through before nailing em down.

[quote=“Bobsleigh”]I haven’t applied the metal valley yet. I needed to do some thinking before taking the snips to it and screwing it up! It WILL completely cover the valley though, past the bottom edge of the ‘upper’ roof and hang over 1/2" or so.

Because CT mixed ‘english’ with ‘metric’ on the same instruction page, I caught a mistake of mine: english are used with 5" exposure, however metric are to use a 5-5/8" exposure.

If I try to shorten a bigger metric shingle to 5" to make it nest into the existing english shingle 3T layout, the new shingle won’t completely seal across it’s length: Part of the tar strip will be ‘flying in air’ in a gap. This is quite noticeable from the ground on my 5/12 pitch. It may also void any warranty. Instead of 100% of the shingle edge adhearing, now only ~ 50% would.

Others have replied that some dim shingles are still avail in english, BUT getting them locally is the problem. The three shingle suppliers I called said they don’t carry english shingles anymore. I did find english 3T’s at the box stores though. . perhaps that’s to distinguish ‘amateur’ from ‘pro’.

Not good. . . . nor acceptable. And trimming 5/8" off of 26 sqrs would be a PITA. Good thing I decided to think this through before nailing em down.[/quote]

The shingles will seal just fine, you wouldn’t happen to be an Engineer or a commercial Pilot would you?

Uh oh…I’ve been made!

OK, the rain has finally stopped, the tarp is off and I’m waiting for the felt to dry a bit before proceeding. My header did mention metal flashing Q’s, so here’s one.

Step flashing vs. “L” or “turnback” where a roof intersects a vertical wall. In my case, the walkway roof butts into the vertical wall of the garage. The research I’ve done indicates step-flashing should be used here. Problem is, it’s hard to find unless I make my own. When I asked ABC and Bradco about this, they said “everyone uses turnback”.

Note the hole nailed through the flashing near the bottom: http://i788.photobucket.com/albums/yy169/SumSol/52c0bc55.jpg Nice! Where they cut a section out near the bottom to make it fit, there was a hole in the siding. I filled it with NP1 temporarily. Digging the nails out of the sidewall was no fun. nor successfull…yet. This thing had pushed the shingles above it about 1-1/2" off the deck. I don’t like the way this looks as it causes a noticeable HUMP in the shingles all the way up. At least the carpenters left enough of a gap so the siding wasn’t sitting on top of the shingles.

So, how do you pros remove these things and do you always go back with step? Anyone use ‘turnback’ or something else? Any advice on detailing the bottom junction where the siding sticks out (with the hole I filled with NP1)? The other side of the roof is much worse…there’s about 12" of space to work in underneath a 12" overhang from the roof line above. (At least no rain will ever get back in there…)

step flashings, and the first step would need to be a diverter so water doesnt go down your wall…

Am I being a little too picky here? Perhaps I should put down my 0.5mm pencil & pickup a carpenters pencil? OK…I get the point! :lol: (I could use a little humor at this point in the project!)

Problem is I keep hearing (reading) differing opinions and have little experience to draw from (except my critical eye!) The CT guy on the phone said “You’ll have shingles all over your yard doing it like that!!” “You’ll VOID the warranty”. He didn’t bother to inquire further before making such an outlandish statement. Just BANG! There it is…next?

So where’s the line between 5" & 5’5/8" and between truth and bravo sierra?

If it’s not that big of a deal and 'butt ‘n run with the gun’ is the way the go, then that’ll work.