Question on Flat Roof water protection
I’m going to be building out a shed dormer — two eventually — on the back side of a Craftsman house. The inside is done (new sub-flooring, insulation, wiring, etc.) and I’m going to be slicing into the roof soon.
I’d like to end up with a flat roof over the new room as I’ve got a solid eight foot wall to conveniently come straight out from to the outer wall. My question is what is the best roof treatment for a flat roof in a rainy environment? I’m not a roofer but figured there MUST be some really good approaches these days to a solid flat roof. Any suggestions for what might be best on a one man ‘handyman’ job?
Also … any sources for the actual approach to coming out from the rafters would be great also. I’ve got some book-sources already but the more the better.
Thanks,
Terry
Replies
If it is meant to be walked on, http://WWW.Duradek.com
I'm thinking it'll be just a roof ... not a 'deck'. So ... walked on as much as a roof is .. which is .. occassionally.
It IS possible that down the line we'd want to set up an outdoor usable space there .. but doubtful.
Thanks -
T
Resource Conservation Technologies (in Baltimore, I think) has a few different flat roof systems. I used a fabric/liquid rubber system on a client's roof deck with excellent results. Installation is easy, and the stuff isn't expensive. It's not made for heavy traffic, but ceertainly walkable. I think the material for an 8' x 10' section cost me about $220, including shipping. The longest part of the installation was waiting for the liquid rubber to dry between coats.These guys advertise a nuber of products in FHB. This is as close as I could get on a google search:http://oikos.com/products/company_detail.lasso?ID=1793-Jonathan Ward
Commercial torch-down roofing will last a long time. 20% more expensive than tar and gravel but lighter, cleaner and better.
When I read "solid flat roof" I wonder if you mean dead flat. At any rate, even a flat roof should have some slope to it. A truely flat roof is not a good thing, and since you are in Seattle I'm guessing that goes double.
I would be using an EPDM (rubber) roof myself. I think the rubber is durable, easy to repair, and is easy to install if you can follow directions. And you can put a deck on top of it later if you want.
Rich Beckman
Another day, another tool.
Edited 1/5/2005 9:23 am ET by Rich Beckman
Torch down, only way to go. Don't go perfectly flat. Rip a 2 x 6 equal to the rafter length in half. Lets say 12'-0. Now rip the resulting 2 3/4" x 12'-0 diagonally length wise spike to the top of the flat rafter, butt against the wall. Each 2 x 6 will provide 4 pitch strips. Nail on sheeting, roofing, wallah. Pull the pitch strips off later if you go up.
I`ve used EPDM on several projects and haven`t had any problems. I did put a slope of 1/4 inch per foot though. The rain has to go somewhere so you should try and direct it. That being said my inspector passed the work but told me to talk people out of flat roofs because they will eventually leak. I`ve been listening to his advice.
I've used EPDM with great success for a long time now and wouldn't consider anything else. I installed it 10 years ago on my own house and it still looks new. I don't know why a building inspector would say it's eventually going to leak. Any roof is eventually going to leak if it isn't replaced when it's lifespan is over.
Having done this job alone I recommend using the heavier gauge rubber-it's a little more work to get up on the roof but alot easier to manage as you roll it onto the contact cement. Insist on getting the manufacturer's installation guide book- I found everything I needed in it and it's really important to use the proper adhesives for the proper function-i.e.; rubber to underlayment, ruber to ruber, ruber to metal curb flashing.
I'm not a roofer but figured there MUST be some really good approaches these days to a solid flat roof. Any suggestions for what might be best on a one man 'handyman' job?
With those credintials, don't even consider torch down. EPDM would be your best choice, but make the decision about what type of roof you're going to use before building the structure. The more slope the better. Go to a roofing supplier and talk to someone knowledgable about the specific product you'll be using and get a parts list together. For EPDM, you'll need the membrane, uncured flashing, roof edge, fasteners, any penetration flashings, termination bar, adhesive, etc. How's it terminate at the top? Partially adhered or fully adhered? Go in with a sketch and as much info as possible and you'll come out better educated. Good luck.
I'm not a roofer, but I play one on Breaktime.
Thanks so much for all the great feedback! Found this little one page explainer on epdm:
http://www.roofhelp.com/choices/epdm/
Looks like that is likely the way to go. ((Just did a search on Homedepot.com and came up with nothing on epdm ... guess they're not going to be my source after all.)) I knew there had to be something out there that was 'the best thing goin' for a flat roof in a rainy climate ... sounds like a nearly uniform vote for rubber.
btw -- my folks bought a house in Seattle in 1961 with a TOTALLY flat roof with higher sides. Every winter it becomes a lake ... from the higher road we've even seen ducks in it! Every summer it dries out and, as a teenager, we used to sleep out on it and hang out in the sun there. It's only leaked ONCE in over 40 years and they simply gooped up the leak. The whole surface is some kind of weird swirled tar concoction ... not anything sophisticated at all ... it's all alligatored and lumpy .. but for some reason it is STILL holding up! I've always heard that flat roofs are leakers ... but this one has heroically defied the odds for WAY longer than I would have imagined possible.
Thanks again,
Terry
The torch down is definitely not a DIY job, it is only a ten to fifteen year roof, and it is more dangerous to apply.( Yessir Mr Insurance Adjustor, I did put the torch dowen there for just a minute, I didn't think it could catch the place on fire thqt quickly. I was only trying to roof the addi....)The EPDM is what you want, but not matter what kind of roof, don't attempt to replicate the unbelievable good luck that other roof had, tho if any material choice can do it, the EPDM will.It's not that ahrd to rip a taper in the 2x12s to provide that recommended 1/4" per foot slope
Give thought to tapering off to both sides from center - depending on where the door will be so you don't have drainage right over the door.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
i'd bet the roof you describe is "pitch" or "pitch tar" i might not be spelling it right... but from what i've been told it use to be the norm on good flat roofs ... I've run into it as the original roof on 100+yo buildings (at the bottom of 20 layers of built up tar) and it still had life to it... still stuck to everything and stunk when u started cut'n into it... as i understand it there may have been some health issues with it's use.. but i also heard it was "self sealing/healing" with hot tar now the refineing has gotten so good that there isn't much good left to make the tar with...
i do like torch down and use a ton of it... just mho
pony
If it were pitch, he would have several unfond memories of having slept out up there on it. It was rarely used on residential, butt I know why you suspect that it might have been pitch. It was the govt spec of choice for ponded roof systems and it is somewhat self healing, but it was also nothing you would be walking on in that osrt of puddled condition.The smell is unmistakeable. i occasionally run into pitch paper under old shingles still.Yes, there are severe health issues. I have torn off a three inch thick pitch roof and have run a pitch kettle. I would rather eat lead and breathe asbestos all day long, then go home to a house filled with tuberculosis, than to have to work with pitch for a living.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
what exactly is it? is it oil based? i was once told it was from pine trees and another time i was told it was from coal? i know it'd stop a 16hp roof cutter like it was hit'n glue... and seems i remember itch'n from it...
thanks
pony
Break some barnches off a fir or pine tree.go back in a day a stick you r hand in the resin running down the trunk most people call sap.nasty aint it? refine it down and you have pitchNoah had a terrible job building that ark - "Pitch it within and without..."I've heard it has also been manufactured as coal tar but the original was from trees.The vapour from hot stuff can crystalize /condense in lungs or eyes and can lead to blindness. It is toxic in your system. The crystaled stuff is very a abrasive irritant. I have had skin rubbed right off at contact points on insides of elbows wher exposed without long sleeves. It was before I knew anything about pitch that I tore off that roof in Texas full of it. That night, I ran a fever of at least 104 and had to sit in a bathtub of cold water for hours, drinking 7UP until the fever went down.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
i do like torch down and use a ton of it... just mho.
pony
I'll take a look at torchdown before actually committing ... but I must admit the epdm'ers have got me thinking that way. Also ... I'll ask around at some roofing stores and suchlike here in rain-city. See what the locals say.
Yeah ... I've been convinced here to definitely build in a little pitch. If 1/4" to the foot is really better than FLAT then I figure I can come up with that as it's only 3 inches in the approximately 12 ft. run I'll be doing.
At the top end I'll be running this epdm (most likely) straight into shingles. They'll only extend up about 2 or 3 feet to the top (pitch?) of the roof. Wondering, also, if I should just run the rubber up and slightly over the roof or come in under the shingles? (If no responses to this now I'll put it out there closer to the job.)
Thanks!
T
Depending on the pitch of the shingle roof,it should run up the slope under the shingles at least 18" - that is true for any flat roof amterial
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
C'mon guys, this is DIY!
No way on the torch-down. Thanks greenCu for jumping on that first.
I'm with Mr. Beckman and the others who suggested EPDM.
And, yes...add a bit of slope to the roof.
> If 1/4" to the foot is really better than FLAT then I figure I can come up with that ....
1/4" per foot is the bare minimum you should ever consider for a flat roof. If you have room to do it, go to 1/2" or even 1". The more encouragement you can give water to go sideways, the better. Especially DIY, you have to think about how accurately you can make that slope. It doesn't take a whole lot of sag or error to get from 1/4" to puddles behind the seams.
-- J.S.
Gotcha.
Thanks John.
T.
EPDM
John Svenson, builder, remodeler, NE Ohio