Is there a proper direction for ridge cap to run when going into a dormor. For example, capping a garage that is lower than the house roof. do you start at the house and go out or opposite?
I usually determine if the house is seeing a lot of wind from a certain direction when determining ridge cap.
Any thoughts?
----> Towards wherever the wind generally comes from.
I always srart the first 2-3 caps on the valley end
of the dormenr so the water will not run under
them and then continue with whatever direction
the wind blows to decide how to finish it.
Where I live it’s south to north and east to west.
I may not know everything, but I do enjoy the process of installing the last cap shingle, as it means there is a celebration because that section is complete.
Installing so the prevailing wind would tend not to lift the cap is the typical advice.
Ten years ago I asked one of the shingle makers, probably GAF, about how to install a cap. They said that suplementing the cement strip with actual cement from a tube was a good idea. I actually do this, running a bead of cement for every cap shingle an inch from the end, being careful not to drop cement on the finished roof.
For my last cap, I use no nails, just lots of cement and weights while it cures.
Call me crazy, if you will, but that is my own personal technique. My ridge caps have held well.
Well, I do know everything and I love that same feeling!
LOL! Just kidding about the “everything” bit!
Bad in my opinion.
What I do is to use 4 nails and then seal the nails with flashing cement and then use the grangules of the shingles to cover the flashing cement.
You have the same granules that protect the roof, protecting the cement that seals the nails and it makes the flashing disappear.
How many years have they “held well” for?
At least ten years. I like the “sprinkle granules” idea. Never saw that, and hate the exposed cement look. Ruins a perfectly well done roof at the last moment. In honor of your greater experience, I will do my next cap precisely as you have suggested.
10 years is halfway through a the life of a roof.
Still early. Plus, it also depends on your region too.
As for my “greater experience”, every once in a while,
I get lucky and come up with a good idea!
I’m not The Great Oz or anything!
LOL
I stand on the shoulders of giants (some of them even here).
But you’re way better off doing it the way it’s been
done for a century and nailing that last ridge cap.
I always run a dormer ridge towards the main body of roof.
Other than that alway run North to South and from East to West. We get more South than North wind but the nasty Winter storms come out of the North. Most wind is from the West but again some come out of the East.
In the past 8 years haven’t had any ridge caps blow off, 4-500 roofs. We do double nail each side though.
Speaking of ridge cap. Just put down some Certinateed Mountain Ridge and was really impressed with the shingle and box design. Very distinct look alot like a cedar shake ridge cap. $4 a foot.
It really depends on the layout of the ridge areas. i usually split a ridge by meeting in the middle if the winds arent much of an issue in the area. For a dormer you would want to start at the edge of dormer and end at the roof field.
Long as your using a good ridge component wind shouldn’t be much of an issue. Out here in California we use Rapid Ridge high profile ridge. They were the first to have a folded leading edge and are rated for over 80 MPH. I’ve talked to the owner a while back and he said they were going for the miami-dade 110 rating and he figured with two nails per side they wouldn’t have a problem getting it.
If you guys haven’t heard of it check it out. its nice stuff and I’ve been using it for years.
I’ll start from both ends and meet in the middle 
what kind of ridge cap are you using?
one end of the ridge peak ends in the field of the roof correct? and one end ends at the gable overhang correct? if so you want to start at the gable end and work your way towards the ridge peak termination at the roof field. if you start at both ends on this layout it will be hard to seal the ridge caps at the shingled field.
If you are using a 3 tab single layer ridge cap then you shouldnt have much of an issue laying the cap underneath the field shingles but it will look better if you start at the gable end. I only use a high profile ridge cap which has to be run as i specified.
hope this helps. a picture could help us understand your situation more because every roof is different.
Marc