Randolph S. E. Carter
|Posted on Wednesday, June 09, 2004 - 08:37 am: ||
A portion of the original roof that had been slate is being replaced with copper. Possibility exists of having to replace a sheathing board or two. The original was oak but finding seasoned oak of the proper diomension may be tough on short notice. What other woods would be acceptable for long term fix? This is a porch roof and the bottom edge board looks a little warped. Is yellow pine OK?
The roof was replaced because the transition from the main roof to the porch roof was a curve which began leaking all the way across and no one here knew how to make the repair. The slate in the curve was set in concrete so that it could be stood on to paint the dormers without breaking the slate.
The first replacement roof was terne metal which I couldnt't keep paint on so it is now going to be replaced with standing seam copper.
|Posted on Wednesday, June 09, 2004 - 06:01 pm: ||
Yellow pine is a good wood. Oak doesn't need to be seasoned, but can be used green. Oak was traditionally used green for building because once it dries, a nail will not penetrate it without bending. You can nail through green oak. The bigger issue is thickness. If you have 1" sheathing boards on your roof, you need to match it with 1" lumber. It doesn't have to be the same wood species.
|Posted on Tuesday, February 08, 2005 - 10:28 am: ||
We are in the process of replacement of the existing slate roof, about 100 years old. The original sheathing had been made of 1"x2" battens @10" o.c. nailed over 3"x5" rafters, 24"o.c.
The roof is about 5:12 pitch.I was debating if we need to remove the old battens and put solid sheathing boards instead, or in order to minimize the stress to the rafters, to fit the boards between the battens? If to fit the new boards between the battens, do we need to make longitudinal joints tight? Using #2 grade of the yellow pine, should it be green or dry? Installed green lumber will shrink and open the gaps along the joints. Will it effects the integrity of the felt paper, nailed over the new solid deck?
Do we need to sister the existing rafters with new 2x6, to support additional weight of new solid green deck?
What is the best practice of the design for ridge vent: closed "caped" or open "vented"?
|Posted on Wednesday, February 09, 2005 - 02:23 am: ||
You can add lumber between the 1x2s. You can also go over top of the 1x2s with wide boards (1x10). Either system will work and I have done both. If going between, and you can fit a 1x4 minimum, then that's the easiest approach. You will need to try to match the original lumber in thickness, so 1" rough-sawn lumber is what you need. 3/4" lumber is not thick enough. Gaps between the boards won't hurt anything. You can felt right over the green lumber.
If you go over top with 1x10s (or whatever width works), keep in mind that you will be nailing the sheathing on with 16 penny nails in order to nail past the 1x2s and into the rafters. We only used this system once, on a hundred year old slate roof with 1x2s battens of oak. They were spaced too close together to be able to fit 1x4s in between, so we went over top of them with 1x10 of rough sawn (green) hemlock lumber. It worked fine, but we had to nail the sheathing on with 16 penny nails. The roof was originally slate, but it was a soft PA slate that was beyond its useful life. We replaced it with salvaged Vermont slate.
You can see photos of these jobs at http://www.joseph-jenkins.com/contract_install.html. The 11th photo down is the farmhouse where we nailed over the 1x2s with 1x10s.
The 10th photo down from the top is the barn where we installed 1x4s between the existing battens.
Scabbing onto the rafter sides in order to beef them up is probably not necessary - certainly not for the weight of the extra sheathing. Are the rafters straight or sagging now? If sagging, they will need beefed up. If straight, you should probably leave them alone. Also, you did not state what kind of wood the rafters are made of. Oak? It makes a difference.
|Posted on Thursday, February 10, 2005 - 12:13 pm: ||
Thanks for your responce.
First of all answering your questions. The rafters and battens are made of hemlock. The existing rafters are about 33lf long and no visual sagging. All battens are in sound condition. The air travels between the battens, cooling the slate. I like your advise of installing green 1x10 rough sawn hemlock lumber over the existing battens, keeping the same air ventilation system. In addition to this I'd like to add a ridge vent for better air exhaust.
The last dilemma I have is to choose the metals for ridge vent capping, flashing, drip edges, gutters and downspouts.
The front and the side of the building is surrounded with an "L" shape porch. The porch and two big dormer roofs had being covered a few years ago with standing seam galvanized metal, because of the low pitch (2:12).
I understand that I can't use new cooper drip edges,flashing and capping in conjunction with existing galvanized porch and dormer metal roofs, and aluminum gutters and downspouts.
It seems to me that the only choice I have, is to choose a heavy gauge aluminum (.032)for all metals over the newly replaced slate roof, to match to the life of slate.
The galvanic scale doesn't allow the use of opposite charged metals. To replace galvanized roofs with cooper is very costly.
If you have different approach, please let me know.
|Posted on Friday, February 11, 2005 - 12:28 pm: ||
First, metal drip edges were never used traditionally on slate roofs and you can eliminate them entirely. You don't need them at the drip edge or on the rake edge. We never use them. Secondly, you can make your hips and ridges out of slate, thereby eliminating any exposed metal. Finally, you can use terne coated stainless steel for valleys and whatnot. This will not impact the galvanized in a negative manner. You can see slate hip and ridge installation at http://www.jenkinsslate.com/install_hips_ridges.htm