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Roofing/Deck on sloped balcony


QUESTION: Hello, John -

I have an apartment with a balcony over my neighbor's living space.  The balcony has a Kemper membrane with bitumen covering.  I'd like to install attractive tiles or pavers over this.

I'm drawn to the pedestal systems, as they don't attach to or penetrate the building's structure (condo rules) and would allow easy removal of the tiles/pavers for repairs underneath.  Also, the balcony is not flat, and the pedestals could be adjusted for high and low points.  However, the pedestals are extremely pricey, as are the special tiles and pavers sold with them.  Tiling my small (115 square foot) balcony this way would cost thousands of dollars for materials alone.

Is there another way to go about this, using items found at a big box store?  Like rubber pads under the corners of standard garden pavers?  Any ideas or suggestions would be very much appreciated.  FYI, I'm in NYC, so everything must be able to withstand cold winters and hot summers.  

Many, many thanks,

ANSWER: Is it mandatory the pavers be level? The slope is there to drain any precipitation off the balcony.
so here are my thoughts:
If an un-level surface is not a problem:
Install a Miradrain (plastic drainage layer over the concrete) and then lay concrete pavers on top.

If you need to level it:
you can by blue (RoofMate) or pink (Foamular) polystyrene insulation to use as pads in the corners. One large piece can hold four corners. But it will be a headache to try and make it exactly level.
buy the adjustable plastic pedestals for four corners of the pavers. might be costly.

Alternately see if you can find recycled plastic or rubber pavers for use on your deck, lighter than concrete with the MiraDrain underneath.

Hope this helps. All the best.

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QUESTION: Thanks, John!  The insulation padding is a great idea.  Two follow-up questions:  

1.  I'd love to do a natural stone paver, 12" or 16" square, 1" thick.  Since only the corners will be supported, is this thickness adequate?  

2.  How large should each corner pad be?  

Again, many thanks!

The natural stone paver I suggest you ask the manufacturer if it will take unsupported foot traffic.
The 12 x 12 paver would be good to use a 4" x 4" piece supporting 4 corners, so each 12 x 12 would have an 8 inch unsupported length in both width x length (2 inches support at each corner). So you need to find out if the centre 8 x 8 inch part of the paver will take foot traffic. If you were to use a 6 x 6" piece there would be no space for drainage under the pavers at all.

You might possibly place a full sheet of insulation underneath if you can obtain the board with drainage channels on the bottom, that way you would not have to cut the board and would have full support everywhere. Sheets are normally 4 x 8 feet in size.

Dow Chemical Ribbed Roofmate= 2 inches thick
Owens Corning- Insul-drain = 1.5 inches thick
         - Foamular 404RB- 1.5" thick.

That way the stone would not have to take any unsupported foot traffic.

Hope this helps


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D. John Henderson


My 33 years in the building science business has involved air barriers, waterproofing, and flat & steep slope roofing systems.


My roofing encompasses commercial systems (BUR, mod-bit, single-ply) and residential applications (asphalt shingles, cedar shingles, slate and metal. I am cognizant of code stipulations in regards to FM and UL for commercial roofs.

Attended numerous courses offerd by Roof Consultants Institute, Roofing Industry Educational Institute, Factory Mutual Research Corporation, University of Wisconsin, and BURSI. Lectured for RCI and mentored at a local university for a Building Science Certificate.

Past/Present Clients
Government, commercial businesses such as The GAP, hospitals, school boards as a roof designer.

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