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-   -   best way to flash flat roof against concrete step (http://www.diychatroom.com/f9/best-way-flash-flat-roof-against-concrete-step-170461/)

noquacks 01-29-2013 08:04 AM

best way to flash flat roof against concrete step
 
people,

Am planning redoing aflat roof, (has a slight pitch, of course). But, the flat roof butts up against a concrete slab (a kind of "patio), and the vertical height of the "step" is about 10". It also is quite a rough surface, making it a challenge to flash neatly. How do they do it?

Also, wont water, during rain, possibly find its way BEHIND the flashing, by seepage? Then, any way to fill holes in the vertical surface to seal it?

Thnaks

jagans 01-29-2013 09:04 AM

You cant flash against the slab, unless the slab is waterproofed. The original roof membrane surely went under the slab. Very poor design with no foresight. Hopefully you left enough of a "Tail" on the original membrane extending out from below the slab to tie into. Since you don't say what the membrane is we need to know that first. How about some pictures?

To answer your second question, yes water will most definitely weep behind your flashing if you don't do this properly.

I can help you if you give me some solid information. Pictures will help a lot.

noquacks 01-29-2013 10:21 AM

Thanks, jagans. Will try for a picture....Meanwhile, yes, seems like a bad design. Now, I didnt destroy the old roof yet!! So, Im still in time. But, I have my doubts that the old membrane does go under the slab.

I should add- looking ahead, I wish to place ceramic tile on this slab. So, if I waterproof it with some paintable material, it will have to adhere to thin set......Double challenges.

jagans 01-29-2013 11:32 AM

First of all, where do you live? Do you get freeze thaw? Post your location, and some pictures. If you have a living space below that slab, I would be willing to bet that the membrane runs under that slab and is flashed at the perimeter.

noquacks 01-29-2013 03:44 PM

Quote:

Originally Posted by jagans (Post 1104896)
First of all, where do you live? Do you get freeze thaw? Post your location, and some pictures. If you have a living space below that slab, I would be willing to bet that the membrane runs under that slab and is flashed at the perimeter.

big thanks again, jag, for folow up. its not where i live, but do own the home in s cal- no freezing. worst- 32 deg f to 105 F.
Oh- just remembered- my other thread! Heres the picture!
http://www.diychatroom.com/f19/remod...ce-how-169601/

See where the old wood deck butts up against the concrete on the right of the picture? Imagine that deck being gone- it will be about 10" deeper with decking and trusses removed......

jagans 01-29-2013 07:14 PM

I dont know what happened to my last post, I asked several questions. I assume by trusses you mean the sleepers holding up the decking planks?

We need to know what the structure is including the structural deck (Thats the one underneath) the exact type of roof membrane, probably a two ply BUR with a mineral surfaced cap sheet? How the sleepers are installed, How the hand rails are installed. etc etc. You need to do some demolition and take some pictures if you want help. Forget tile. Take a look at Hanover Prest Pavers.

noquacks 01-30-2013 08:21 AM

Quote:

Originally Posted by jagans (Post 1105162)
I dont know what happened to my last post, I asked several questions. I assume by trusses you mean the sleepers holding up the decking planks?

We need to know what the structure is including the structural deck (Thats the one underneath) the exact type of roof membrane, probably a two ply BUR with a mineral surfaced cap sheet? How the sleepers are installed, How the hand rails are installed. etc etc. You need to do some demolition and take some pictures if you want help. Forget tile. Take a look at Hanover Prest Pavers.

Right- I meant the "sleepers" (guess I learnt a new word) , the "frame" under deck. I think theyre 2X6's which span the entire deck, and bolt onto each 4X4 post, NOT lay on top of the roof membrane. Guess pretty/authentic tile are out, as members also recommended on the other thread I had. Will look up these prest pavers (fake plastic material?)

I will advise asap on what holds up the roof------guesssing 2X6's also, maybe 2X8's......

noquacks 01-30-2013 08:23 AM

Man, here they are:
http://www.hanoverpavers.com/

arnt thos pavers HEAVY? Cant overload my roof surface with extra weight- Im at my limit right now......

jagans 01-30-2013 09:10 PM

Yes, they are 22.5 lbs per sq. ft. Plastic goes away with UV. Low density pavers fall apart. I thought you said you wanted to renovate this deck. Yes you would probably have to increase the design load. Considering how many people could go out there, I would build up its load carrying capacity.

We still need pictures of the edge of the slab and the roof membrane etc.

You also did not tell us if you have leaks.

noquacks 02-01-2013 03:53 PM

yeah, we got bad leaks! been limping along with patches that dont work. wood looks so tacky. so, how do you determined its 22.5lb/sf? doesnt that mean if a guy who is 200lbs standing withion the normal stance of 1sf or so will collapse?? curious.....
i understand you need pictures of the underneath, but since we havnt torn it apart yet (cuz we still are planning), no pictures if the innards....


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