| Author |
Message |
Steven Hauk
Senior Member
Username: sh1net
Post Number: 19
Registered: 12-2004
| | Posted on Tuesday, March 10, 2009 - 07:47 pm: |    |
What's the prevailing thought for waterproofing on balconies in mid-quality wood construction, under a concrete topping? 60-mil rubberized asphalt sheet? |
William C. Pegues, FCSI, CCS
Senior Member
Username: wpegues
Post Number: 781
Registered: 10-2002
| | Posted on Tuesday, March 10, 2009 - 08:51 pm: | |
Where is the membrane going, under a concrete topping?
So what is the substrate that the membrane is supposed to adhere to? Wood? That is what supports the concrete?
I think it might help to know a bit more about the sandwich that makes up the materials in this slab.
William
William C. Pegues, FCSI, CCS, SCIP Affiliate
WDG Architecture, Washington, DC | Dallas, TX |
Jerome J. Lazar, RA, CCS, CSI, SCIP
Senior Member
Username: lazarcitec
Post Number: 659
Registered: 05-2003
| | Posted on Tuesday, March 10, 2009 - 10:43 pm: | |
Also, what will the finaly balcony finish be, if its tile, Ditra membrane by Schulter is one of our favorites for balconies..when it comes to waterproofing we always spec the best even if it is "mid-quality construction', when it leaks you can't blame cost issues if you specified an inferior product, we let the Owner and GC manipulate the specs (VE) if they are that careless when it comes to waterproofing integrity and money. |
Steven Hauk
Senior Member
Username: sh1net
Post Number: 20
Registered: 12-2004
| | Posted on Wednesday, March 11, 2009 - 12:12 am: | |
The membrane goes under a concrete topping and drainage board, like Enkadrain. The membrane adheres to a wood deck on wood trusses. So the sandwich is concrete, drainage board, waterproofing, and wood deck. The wood deck slopes down to the edge.
Probably of significance to this topic is the concrete edge, which is an aluminum T bar. The contractor shims the T bar up with squares of waterproofing so drainage that gets through the concrete is supposed to weep below the T bar. |
William C. Pegues, FCSI, CCS
Senior Member
Username: wpegues
Post Number: 782
Registered: 10-2002
| | Posted on Wednesday, March 11, 2009 - 12:31 am: | |
You are using the drainage board (Enkadrain like) for what reason? Most 'soft' and many other waterproofing membranes are going to require a protection mat product over the waterproofing. Most even if there is no drainage board material they will require a protection product over the waterproofing.
Not sure I would bother with the drainage board, when I sandwich a waterproofing membrane under a concrete wearing surface, I typically don't. Many membrane details from manufacturer's don't require it either.
If you wish to shim the T-Bar edge, use something other than waterproofing 'squares'. The membrane material you are considering is easily compressed.
The membrane you are looking at, rubberized asphalt sheet, works, but, you are obviously bringing it out to the edge, likely exposed. Those membranes do not do well in that regard, they can tend to soften and 'ooze' on hot days and I have some wonderful pictures of the similar material in flashing from someone else's project with black drips running down the facade. If you were to go with this kind of membrane, you would need to detail it like flashing - with a stainless steel edge where the waterproofing membrane is held back from the edge by 1/2 inch minimum and the stainless steel edging goes out to the edge. You don't need the turn down drip type - though some waterproofing consultants might say you do. There are multiple reasons not to do so.
I would seriously consider a membrane that did not have any detailing concerns like metal edges. Something say like a PVC membrane that is thermoplastic and heat weldable. You can carry it right to the edge, no problem.
All of this is assuming that the space below is not an enclosed/conditioned occupied space (meaning the space below is another deck space, not an enclosed room. If you get into an enclosed room below, you want to move to a true roofing membrane solution.
William
William C. Pegues, FCSI, CCS, SCIP Affiliate
WDG Architecture, Washington, DC | Dallas, TX |
Steven Hauk
Senior Member
Username: sh1net
Post Number: 21
Registered: 12-2004
| | Posted on Wednesday, March 11, 2009 - 01:26 am: | |
I should clarify...the assembly is proposed by the contractor. A single subcontractor will provide the waterproofing system, the flashing and the topping. This assembly came in as a submittal, as did the interior assembly with Acoustimat and gypcrete on the wood deck.
And to fill in background info...The space below isn't enclosed. These are cantilevered balconies in a plan that's identical on every floor. Sometimes the exterior wall is recessed around the balcony, but nevertheless, they're cantilevered and open-air below.
PVC is what I thought I'd see submitted...and it wasn't there. I figured maybe these guys knew something I needed to check into. I've been accustomed to assuming concrete toppings shed the water and the waterproofing is back-up. The proposed assembly seems to treat it like the waterproofing is the primary...like an open-joint paver system. |
Curt Norton, CSI, CCS
Senior Member
Username: curtn
Post Number: 139
Registered: 06-2002
| | Posted on Wednesday, March 11, 2009 - 09:43 am: | |
I ran across this product a few months ago. I haven't had time to review it, but it looks very promising for stacked exterior balconies. It would probably require some redesign. http://www.xccentdecking.com/drydeck.html |
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