Wood Sleepers over Torch-Down Primary Roofing Waterproofing: Exterior Deck over Living Space

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JohnfrWhipple

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I have a pickle of a design dilemma today. I have been asked to fix a poor draining torch on deck. The deck is not draining all that well and the builder has asked for a solution. The deck will get sleepers and some kind of Cedar or Composite Decking boards.

The torch on is not the best (poor sloping and pitch) but has passed a local inspection and is as far a s the city goes - Good To Go.

I want to place some sleepers down. Have them graded to the West Corner. And then infill the sleepers so the deck can not hold so much water.

New torch on and a do over is not going to happen. Siding is on. Stucco is up.

I have called Ardex about 8+9 and my rep does not like it. I'm told this is a no go.

What I'm thinking is to coat out the torch on with Ardex 8+9. Three coats. Set the sleepers with Ardex 8+9 and angle iron.

In fill between sleepers with Mapecem premix.

Coat the entire thing out with more 8+9.

Screw the new decking to the sleepers.

Call it a day.

The concept is kind of like adding a brick to a toilet bowl tank.

What do you think Roberto? RSCB? have you tried anything like this before. The deck does not leak. Leaving the deck as is will mean there is a breeding ground for mosquitoes year round.
 

Eurob

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John , I don't think your plan is going to work . Too many things can go wrong if water penetrates below the new deck .

How much build up -- in inches --you need to make it work ?


I would cut , as a first choice , the torch on 18'' from the siding , remove everything and rework the structure -- removing the minimum material necessary to allow the proper sloping , then cover it back to original torch on membrane .
 

JohnfrWhipple

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That is what I suggested. I told the builder about the torch on pre-slope kits. Told him to do it. The torch on guys came back and just capped off the one drain. Now the deck has one drain and two scuppers. So by code it's still good to go.

I could see his face if I said I need to break out the Stucco and do a do over for the do over.... lol :)

I guess I'm thinking that I will get a pretty good bite with the Ardex 8+9 over the torch on. Then the screed mortar to fix the grading. Then wait a few days (going to hit it from 1" to 1/4" over 21'). Then more 8+9.

I have some old Jiffy Seal 140/60 that I'm going to lay down over top now I think. Since the 8+9 is not a wear surface.

Can you say.....

Santa-Cruz-Cowboy,-California.jpg

Cowboy​
 

Jadnashua

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There are some jobs you should just pass on...this is likely one of them. Let some other yahoo take the hit. Wood sleepers, surrounded by waterproofing, then screws into them? They'll likely all rot, then there's nothing holding your surface in place except gravity. You wouldn't build a shower curb, then put screws into it no matter how well you tried to waterproof them. Why would you expect wood to survive in this?
 

Eurob

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That is what I suggested. I told the builder about the torch on pre-slope kits. Told him to do it. The torch on guys came back and just capped off the one drain. Now the deck has one drain and two scuppers. So by code it's still good to go.

I could see his face if I said I need to break out the Stucco and do a do over for the do over.... lol :)

I guess I'm thinking that I will get a pretty good bite with the Ardex 8+9 over the torch on. Then the screed mortar to fix the grading. Then wait a few days (going to hit it from 1" to 1/4" over 21'). Then more 8+9.

I have some old Jiffy Seal 140/60 that I'm going to lay down over top now I think. Since the 8+9 is not a wear surface.

Can you say..... cowboy


John , agreeing to accommodate a problematic build by '' patching '' over it , the problem becomes yours -- transfer of responsibility -- . First the warranty on the torch on membrane -- roofers -- gets out the drain , second the builder -- improper slope -- can claim '' innocence '' once it is covered and third , if your system doesn't work , it can really get you in trouble .

I didn't think of you being a '' go cowboy '' pro , but usually the re-do costs less than a patching over . Your call , your client . And without any pictures I can not even see what is going on there .
 

JohnfrWhipple

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Typically I'm not a cowboy. The torch on work is solid. I plan to add further waterproofing to it. Kind of like making a really large concrete tile waterproofed on six sides.

I could simply add concrete pavers and have thought of that too.

It's a tough call Roberto. I'd like to help the builder out. Will see what he thinks of my price. In the end I think the deck might just stay the way it is. Maybe the simplest approach is to cover it with pea gravel....
 

Eurob

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This is only because water is pooling on a section of the deck, right ?

The situation has to be assessed on site . Hard to say what the real conditions are from here . Is it sagging or just improper built ? Adding weight could create another issue . How the structure is built ?

You need all the information before you can present a valuable fix , I would say . :)
 

Eurob

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I think 1/2'' or less of intermittent water accumulations is considered not to be a problem for flat roofs with torch on membranes , especially if it is only present at the overlapping junctions .

What is the slope % on the structural plan ?
 
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