|Posted on Friday, February 18, 2005 - 10:00 pm: ||
Am replacing a leaking terne metal ridge cap (roll?), would like to use copper for the new one.
My contractor says the roll may have leaked for two reasons: insufficient headlap and corrosion. I have not owned the house very long, so I can't say if the design is poor or if the metal is just worn out.
Well, I know the metal is worn out. You can poke a hole in the metal with your finger, if you find a "soft" spot. Don't ask how I know! I just don't know much about the other issue: headlap.
I've read through the The Slate Roof Bible, 2nd Edition does not specify headlaps for metal ridges. The contractor says my ridge has only 2" of headlap. Mr. Jenkins states somewhere else in the book that some older roofs only had 2" headlap on the slates, and they worked OK (can't remember the exact page of this reference). Are the two equal?
I'd like to use the same profile as is currently installed, but need to know if I need to extend it further down the roof. Can anyone specify a minimum headlap requirement?
|Posted on Saturday, February 19, 2005 - 05:45 am: ||
Hi, A 3" headlap is more common than a 2" headlap and provides better coverage from blowing rains especially at the peak of ones roof. Go the extra inch of headlap,plus this helps to cover the old nail holes of the existing ridge cap..Although a 2" headlap is fine for steeper roof applications such as a 10/12 pitch and above.
|Posted on Sunday, February 20, 2005 - 03:06 pm: ||
Your ridge is leaking because the metal is worn out and/or the nail heads are leaking. It's a simple matter to replace the metal with new by removing the old, repairing any broken slates under the ridge, and nailing the new metal into place, then caulking the nail heads with good caulk (GE Silicon II,clear caulk, is recommended). There is not usually a headlap issue at the ridge. The last two courses of slate usually terminate at the ridgeline, so headlap does not need to be a concern.
One issue is old nail holes from the old ridge, which Slateworks mentions. Sometimes the new ridge will not completely cover the old nails holes. You must very carefully and closely look on both sides of the new ridge (when you're caulking the new nails) for these old stray holes (they may be slightly underneath the new ridge, so you really have to look close) and be sure to caulk them too.
Otherwise, use a wider ridge. We replace old terne metal ridges with new 16 ounce copper ridges made from stock that is 2" wider than the original. If I remember correctly, the original terne ridge roll is made from 10" stock and we're using copper ridge roll made from 12" stock. That extra inch on both sides makes a big difference in covering up the ridge and making it water proof.
We also sell these copper ridges for $65/10 feet, but we don't ship them - they're only for pick up here in western PA.
|Posted on Sunday, February 20, 2005 - 07:18 pm: ||
As your contractor has examined the ridged it may be that he could see the slates stopped a little short of the ridge.
Also he may have been referring to the overlap of the metal, I know some contractors who call that a head lap, it's really an overlap.
There should be no problem in your contractor fitting a wider ridge, while 3" may be acceptable, he can extend out to 4" and cover any old nail holes after they are repaired.
We use a clip system when fitting copper ridge as it holds the metal tight into the roll, we also turn a watercheck at the laps.
Peter Crawley, M.I.o.R.
|Posted on Monday, February 21, 2005 - 09:40 pm: ||
Thank you for responding to my query!
I believe the second to the last course of slates butts into a cant strip, then the last course is nailed to it . . .
Although the contractor seems reputable, it never hurts to get a second opinion!