*
I would like to roof a 3-seasons sunroom using cedar shakes to compliment the main house. I was constrained to a 3/12 roof pitch and incorporated a vaulted section (radius about 2.5 feet) at the roof/wall junction to avoid an unappealing shed roofline. I have been advised to cover the ply sheathing with ice and water shield, continue it down the wall ply and then proceed normally with 30 lb. underlay between shake courses at 5 inch exposure. To apply shakes on top of the vault, it was suggested, would require trimming the shakes to an appropriate length. I was also planning to bring the shakes partway down the wall to just about the window line so a flashing would be required. If this application is feasible what shake trimming and flashing recommendations are advisable.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Listeners write in about haunted pipes and building-science tomes, and they ask questions about roof venting and roof leaks.
Highlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
*
Alex Salki - 07:08pm Sep 1, 2000 EST
I would like to roof a 3-seasons sunroom using cedar shakes to compliment the main house. I was constrained to a 3/12 roof pitch and incorporated a vaulted section (radius about 2.5 feet) at the roof/wall junction to avoid an unappealing shed roofline. I have been advised to cover the ply sheathing with ice and water shield, continue it down the wall ply and then proceed normally with 30 lb. underlay between shake courses at 5 inch exposure. To apply shakes on top of the vault, it was suggested, would require trimming the shakes to an appropriate length. I was also planning to bring the shakes partway down the wall to just about the window line so a flashing would be required. If this application is feasible what shake trimming and flashing recommendations are advisable.
*
Alex, what? I don't understand how you build a 3/12 vault with a radius. You can build a barrel vault with a 2.5' radius. Your post makes it sound like your roof has a radius on the exterior surface that starts at the wall and ends with your 3/12 pitch roof. I know it's Fri. before a long weekend, so maybe I'm just a little slow right now, but I don't understand.
*
Hi Steve. You correctly interpreted my imprecisely described roof design. Yes, a 6 foot wall transforms into a curved roof section (r=2.5 feet- is this termed a one half vault)and then rises as a roof with a 3/12 pitch. Basically a shed with a curve at the wall/roof junction. Yes its Friday of a long week. Had fun making the curved connecting rafters of plywood though and then applying two layers of 1/4 inch plywood on the curve to act as roof sheathing. Hope you have some suggestions.
*
Alex, will there be any insulation and/or vapor barrier?
*3 in 12 sure is a low pitch for cedar shakes. Hope it doesn't snow there.
*Who advised you to put shakes over ply sheathing? I don't think the ice and water shield will do anything for you but cause the shakes to rot. You need better advice.
*
Hi Steve, Yes I was planning to insulate and VB at least one part of the roof and a small wall section that will perhaps help extend use of the room into the earlier spring and late fall. I dont anticipate using it in the winter since Winnipeg's design temp is -33 F. I will fill the 2x6 rafter cavity with insulation (perhaps SM), then a HD VB, then 3/4 foil faced polyisocyanurate then finish interior with 1x4 cedar. I will fabricate my double glazed windows using tinted tempered glass (picked up for pennies from a bankrupt solarium distributor) set in a cedar or redwood frame. But first to get the roof on. Thanks
*Hi Mad Dog, Yes I thought the 3/12 was a bit shallow for shakes but one of the premier cedar roofers in our city advised me to follow this technique. The house adjoining the sunroom has a 6/12 slope and the shakes over ply is performing perfectly. (I know this because when I replaced a section of roof danaged by a heavy hail storm, the fir ply roof sheathing was still like new.) I originally thought to go to a sheet metal roof on the sunroom and still may after getting a concensus. Thanks
*
I would like to roof a 3-seasons sunroom using cedar shakes to compliment the main house. I was constrained to a 3/12 roof pitch and incorporated a vaulted section (radius about 2.5 feet) at the roof/wall junction to avoid an unappealing shed roofline. I have been advised to cover the ply sheathing with ice and water shield, continue it down the wall ply and then proceed normally with 30 lb. underlay between shake courses at 5 inch exposure. To apply shakes on top of the vault, it was suggested, would require trimming the shakes to an appropriate length. I was also planning to bring the shakes partway down the wall to just about the window line so a flashing would be required. If this application is feasible what shake trimming and flashing recommendations are advisable.
*
Alex, here are my concerns.
1. You have a "hot'" roof, no ventilation, make sure your vapor barrier is unbroken. Tape all seams, use Lesco boxes behind any electrical openings and tape your vapor barrier to them.
2. The fact that your roof transitions to your wall with no break means that all the water that runs off your roof will run down your side walls. You could run ice and water all the way down the walls, but then you have the problem of a double vapor barrier. I would think about using Cedar Breather or firring strips behind your shingles so there is an opportunity for things to dry out. A better solution would be some kind of a break between roof and wall allowing water to drip off and air to circulate under the roof.
So here is my solution for you. Fir your roof area up with 1x2s. run then every 5" so you can nail your shingles to them. Leave some spaces between them so air can flow through to ridge where you should use Cobra vent or similar under your ridge shingles. At the roof /wall transition use a row of Cor A Vent ( see add in FHB) and hang the first row of roof shingles 1-1/2" below the vent. You are still going to have water running down the wall, though not quite as problematic. Use type D felt behind the wall shingles.
Good luck, Steve