Howdy,
This is my first post but I’ve been a subscriber for better than a decade and have been reading this column in the print version for a while. I’ve got a redwood house on the north coast of California. The existing roof is heavy redwood shake, but it’s 30 years old and I’ve been fixing it regularly for 5.
I’m planning to replace the shake with a high quality composition shingle this summer. I’ve dreamed about copper, but I don’t think I can afford it. The tricky part is the construction. The roof is made of 2×6 inch toung-and-groove redwood. The inside of the roof is the interior ceiling and the outside is to weather.
My first thought was to remove the old roof, seal the 2 inch redwood t&g with a high quality wood sealer (Daly’s Ship and Shore), then slap down 30 pound felt and just nail the shingles on.
On second thought, I’m thinking I should make sure the roof can “breathe”.
I would appreciate some professional advice on 1) whether sealing the roof with wood sealer would be a good idea?
2) Should I attach furring strips and plywood over the 2×6 redwood so it can breathe? If so, a ridge vent would probably be in order.
3) Is there a better way to roof this building?
The roof is about 40 degrees, and it is an A-frame type structure with no valleys. The climate is generally cool and moist, summer max is 85 degrees F, but that is rare. The south side gets the sun, most of the wind from the west.
Thanks for the help.
rich
Replies
Here's what I would recommend. The only thing wrong with your roof as is, is that you have absolutely no insulation.
Remove the existing shakes and clean up.
Apply a layer of 2" foam board.
Use furring strips (1x4") laid horizontally at 16" to 24" OC to hold the foam in place and create a "cold roof" Use five inch screws to fasten them in place. I use Reisser screws from GRK Canada. They rarely break and the Torx head makes them easy to install. Any good deck or structural screw will work.
Nail a plywood deck over the furring.
Have a custom copper eave edge made with a four inch face to cover the edges of the material you have built up.
Cover with thirty pound felt and then the architectural grade shingles.
The extra insulation work should pay for itself in energy savings.
Excellence is its own reward!
Thanks Piffin,
The insulation is a good idea. For breathe-ability wouldn't vertical furring with a ridge vent be better than horizontal?
rich
I'm going to agree that insulating this roof is a good idea even though I wrongly tend to think of California basking in the mid 70's year round. (20 more inches of snow here in Pennsylvania this week.....) The method Piffin has recommended is great, it's just a little labor intensive. You can buy polyiso ventilated nailboard for this application which could save you a lot of money. The roof gets ventilated at the bottom and top as always. You should call your local roofing (commercial) supplier to get pricing on this stuff. It isn't cheap, but as is often the case, it is a big labor saver. Take a look at the link below to view the product.
http://www.pacesupplycorp.com/roofing_sheathing.htm
By the way, the product shown in this link is polyiso only, normally when we buy it, we specify the product as a ventilated polyiso as shown with a layer of 1/2" plywood or OSB already bonded to the sheet for shingle nailing.
carpenter in transition
Edited 2/22/2003 4:36:20 PM ET by TIM_KLINE
Nice site and good drawings!.
Excellence is its own reward!
Thanks Tim,
That looks like a great product for this application. I think I've got a plan now.
rich
I suppose it would.
Just never did it that way before! I kind of like being able to walk on the roof without sliding off and horizonatl makes a good chicken ladder. And most of the roofs i have refitted like this were metal so with that I eliminate the top ply of plywood and fasten the metal directly to the furring. Old brains like mine are slower to make the new application..
Excellence is its own reward!
phiffin is right about the insulation but just as important is the ventilation. I would reccoment going to certainteed.com and ordering (I think it is free) the video about the importance of attic (and any kind of roof for that matter) ventilation. As a matter of fact some warranties are severely limited on roofing if the proper ventilation isn't in order. I know that any certainteed warranty is limited to 10 years instead of 20, 30, or even the 40 years! Just someting to seriously consider. Proper venilation greatly increases the life of your roof.