Hello To Everyone!
Two days ago I discovered that the wind had ‘peeled back’ the roof – rolled roofing material and tar paper ( no shingles ) – from over our flat-roofed den. It is roughly 16′ x 18′ in area and the pitch is very flat, 1:6, I would say.
When I climbed up to make my inspection I was further surprised to see that 1″ x 6″ rough-cut lumber had been used rather than plywood sheathing to form the roof decking. Our home is an Oak Park, IL bungalow and being from NM, I do not know what construction practices to expect in this part of the US. I’m accustomed to seeing 4′ x 8′ sheathing material used rather than loose lumber for roof decking. In my opinion it’s a ‘no brainer’ to use the sheathing as it goes on faster and provides a far superior surface for laying the roof down. However, years ago this may not have been the preferred construction practice.
This den was an addition and not part of the original brick construction. My neighbor has lived next door for 30 years and believes that the addition was there when they moved in. I say this because someone may be able to relate construction practices employed at that time.
My repair plan is as follows. Strip the old roofing material off and remove the sheathing. Check for water damage and repair as necessary. Once this is done I will lay on the plywood decking.
I have seen some 4′ x 8′ sheathing material which is seemingly pressed wood but coated or impregnated with plastic or some form of hardened glue which is impervious to moisture. This is no doubt superior to the garden variety PW.
Once this phase is complete, I want to use a tin roof. Many homes in NM are covered with plastic ( I believe ) coated galvanized tin roofing. This coating may also be a baked on enamel paint. I am not certain of this. This material comes in many colors, is channeled to give it strength, is manufactured in manageable sheets, and is simple to put on. And, it is maintenance free. This may not be the best choice of roofing for an almost flat roof so all of this is open for discussion.
If possible, I may increase the pitch of this roof. Flat roofs can be nothing but trouble unless the construction process utilized is flawless. However, from an economic perspective this may not be feasible. From a construction point of veiw, it may not be possible without a lot of modification at the main-house to den junction, all of which takes us right back to cost. At this point in time it is raining so I cannot climb up and ‘think’ about it.
In case anyone is wondering, I did manage to un-peel the roofing material so that we do have some protection from the elements. I also do have roofing experience so can certainly do this myself. I say ‘experience’ because I constructed a thousand foot addition to a home I used to own and did do the roof as well. Not much fun, but rewarding in that it was done correctly and gave me the opportunity to learn about this phase of home construction.
Your input would be greatly appreciated. Thank You! to all of you in advance.
Regards,
Phillip
Replies
Anyway to increase the slope?
Flat roofs fight mother nature and gravity
The board sheathing is probably are reflection of the age of the house. That's what was used before plywood was available.
As I understand your situation, I would consider this approach first: Strip the old asphalt. Repair any rot. Leave the sheathing alone if it's sound. Apply a rubber roof with it's fiberboard underlayment.
I'm pretty sure rubber is state-of-the-art for low-slope roofs, but I know almost nothing about metal roofs.
Al Mollitor, Sharon MA
I have seen PVC roofing on flat residential roofs a couple of times recently. They weld the sheets together into a monolithic piece. Apparently good and quite expensive, and it's BRIGHT.
Plywood came into widespread use about the time of WWII. Decorative veneers had been around long before that, but not until the late '30's was it economically practical to lay up layers like that using inexpensive structural woods. Your addition could either be that old, or done within a couple decades of the war by an old timer who preferred solid sawn to plywood. Or maybe he got a deal on the lumber. Dating things by construction decisions is very approximate, because things overlap a lot.
That "seemingly pressed wood" stuff is called OSB, Oriented Strand Board. Nobody likes it as well as real plywood, no way is it better. But for the price and purpose, it's adequate.
You don't necessarily have to demo the solid sawn sheathing. Strip the roof down to it, then check for termites and rot. If it's just a few pieces here and there, don't waste your money and effort replacing all of it. If you do pull it all off, sort out the good stuff and save it to re-mill. There's value in seasoned old growth wood. Sell it if you don't want it yourself.
-- J.S.
Commercial type torchdown or membrane roofing with careful attention to flashings, coversheets, number of fasteners/sq ft, etc. Used on millions of commercial flat roofs nation wide. Get several bids, you'll find quite a range of pricing, but a good job should be available at a competitive price.
Here's another good place to look:
http://www.conservationtechnology.com/
They have a few different ways to do flat roofs, plus a lot of gasket, weatherstrip, and caulk type things. The roof in question is 2 in 12, which should work very well with the RCT systems.
-- J.S.