Hello all,
I have an 8′ x 12′ shed roof that needs to be replaced. I would like to be able to walk on it since there is a door from the second floor onto the roof. I was thinking of some sort of metal – copper, aluminum or steel. Whatever the material, what other layers do I need? 30 lb felt…
The current sheathing is 1 x 6″ pine. Is this good because of the airflow afforded by the gaps? Would plywood or OSB be better?
Any advice would be greatly appreciated.
Thanks,
Scott
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Replies
What's the pitch of the roof? What kind of roofing material is/was on it? How often do you plan to walk on it?
The roof pitch is 1" rise in 12" run. The original material was 1 x 6 sheathing covered with felt, then asphalt roll roofing. The structure is 2x4 ceiling joists and roof rafters that meet side-by-side at the low end of the roof.I would like to treat it as an occasional deck, meaning sit out there in plastic lawn chairs once in a while.
Unless you beef up your 2x4 rafters, don't even think of sticking people on your 'deck'. An easy, DIY, low-slope, roofing material is EPDM. You apply it over a layer of plywood which you can put over your boards or remove the boards and attach the ply to the rafters directly. The rubber roofing sheet is adhered with contact cement made for the material. You can pull the material under the eaves, staple it, and put trim over it to finish and make the eaves and fascia watertight, too. The .045 thickness is fine for this job. http://www.roofhelp.com/choices/epdm/http://www.mulehide.com/epdm/epdm.html
I'm with Splinter. Double up the rafters. Lay 1/2" plywood on top of the 1X6, nailed or screwed through to the new 2X4s. EPDM, installed with adhesive per manufacturer's recommendations.
Edit: If you're very concerned about the roof load, you could sandwich plywood between the doubled rafters. I'd probably start some screws in the new rafters before putting them in place. Pounding nails into old DF 2X4s doesn't usually go real well.
Edited 6/21/2007 2:48 pm ET by Hudson Valley Carpenter
The structure is a bump-out on a 1929 bungalow. The main structure is brick veneer on balloon-frame. The second floor of the main structure has a door onto the shed roof of the bump-out. There is a 7" step down from the door threshold to the roof, so there probably is some space to add rafter width. Are you suggesting to add another 2x4 to the top edge of the existing rafters? If so, glue & screw or? Is there any reason to leave the existing 1x6 sheathing, or tear it up and lay plywood over the improved rafters? I would rather not tear out the existing rafters since they are toe-nailed to the main structure's wall studs and any demo would eat them up.I have attached drawings filed for the permit. The header shown actually spans the structure and directly supports the rafters and joists.Thanks for all your help,Scott
You can leave the existing rafters and the inch boards. What they are talking about with sistering on is to take your new rafters (2x whatever necessary for loads), and butting them both up to the 1x6s and the side of the existing rafters. You'll probably need to push on them a fair bit to take out bows/sags in the old roof. I would also recommend using PL Premium construction adhesive when sistering.I've never used EDPM, but I'm guessing it would be a good call to add some plywood on top of the skip sheathing.Probably have to experiment with nails vs. screws. Nails would be nice, but given the age of the wood, it might be more trouble than it's worth.
Here's another link to explain strengthening framing members by "sistering" larger members next to the old ones, with pictures.
The sistered rafters are placed alongside the existing rafters, normally with the upper edges of the two rafters being in plane. If you have a finished ceiling in your porch you are loathe to destroy, however, you can remove the 1x6 board roof decking and sister the new to the old with the bottom edges being even, then build a new deck on that with 3/4"plywood.
If you have sag in your roof, you should jack up the sagging rafters before screwing the sistered rafters alongside. Use 3" lag screws or 16d nails with construction adhesive between the old and new sistered rafter. I find turning screws with a cordless drill fitted with a socket easier to deal with than hammering nails, but that's your call. If you screw, pre-drill starter holes in the sister rafter before putting it up.
Edited 6/22/2007 2:52 am ET by splintergroupie
Splinter's advice is all good stuff, well explained too. I found this part particularly useful.
Use 3" lag screws or 16d nails with construction adhesive between the old and new sistered rafter. I find turning screws with a cordless drill fitted with a socket easier to deal with than hammering nails, but that's your call. If you screw, pre-drill starter holes in the sister rafter before putting it up.
As you may know, lag screws have hex heads, like small bolts and nuts. Using a 1/4" drive socket fitted to a short extension, held in the chuck of your drill will allow you to drive the screws into the old 2X4 with relative ease, even if your hand/arm position is awkward. Lag screws are available in small diameters too, almost as small as piffen screws*.
*dry wall
Continuing with this project...
I have the week off from my day-job, so I am tackling this project with reckless abandon. The 8 x 12' shed roof had eaves perpendicular to the last rafter which were supported only by the roof sheathing, which was 1x6 pine. Yikes! Crunchy the drying squirrel was guarding the eaves in his/her fiberglass nest. The building inspector suggested building a ladder soffit from 2x6 lumber, then nailing/bolting it to the exterior wall. I don't really want or need facia wider than 6", so this brings 2 questions. Since I want the soffit to be recessed above the lower edge of the facia, doesn't the 2x6 requirement mean I am forced to have a wider facia? Should the roof sheathing sit on top of the facia board edge or within it? Since I'm rebuilding the roof, precedence holds little muster, but the existing structure had the 1x6 roof sheathing within the facia. The back edge of the roof has soffit built off the rafter tails.Thanks,Scott
The other running argument is 3/4" vs 5/8" roof sheathing. My brother-in-law is a carpenter, says 3/4", the building inspector says save your back - 5/8".
Had a similar thread a few months ago.
Best value SHED roof is old flattened car hoods, followed by scrap formica sheets and old whiteboard sheet metal fronts.
Also rans were license plate shingles, split your own shakes, flattened 5 cal cans, split old tires, etc.
The shed to the left of the pix is an old whiteboard sheet metal roof <G>
View Image
Edited 6/20/2007 8:16 am ET by junkhound
Edited 6/20/2007 8:16 am ET by junkhound
Use EPDM roofing membrane. Double up your joist first to 2x8's sistered to the existing ones. Then put 1/2" plywood on top of that. Glue down the EPDM and it will last a long time. If you can find it at a roofing supply store look online at http://www.flatroofsolutions.com/aboutepdm.html
Btw 45mil should be good enough.
Martin