# Forum Home Renovation Waterproofing  Build a rooftop terrace/balcony on top of existing ceiling

## world2160

I am about to do a second storey addition on my house. As part of the addition, I want to have a rooftop terrace/large balcony (20-30 sqm), sitting on top of the ground floor ceiling. It's not floating.  I've talked to some builders and they reckon it is asking for trouble because it will surely leak someday.  - Is it true that no matter how good the water proofing is, it will leak in the near future?  - If it does leak, do we have to rip out the tiles and redo the floor?

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## David.Elliott

I'm no builder, but I'd be tempted to construct a proper roof with steel at 5? degrees and float a deck above that...

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## world2160

> I'm no builder, but I'd be tempted to construct a proper roof with steel at 5? degrees and float a deck above that...

  Interesting idea. However this will add more height to be overall building making my DA even harder. Has anyone done this before?

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## OBBob

We don't seem to do this stuff very well here ... look at home many apartment balconies seem to manage to leak into garages or apartments below. In Europe it seems quite common and they use bitumen waterproofing systems that are joined in situ with heat guns. I'm with David ... I'd like to see the physical separation ... but if you are willing to pay then I'm sure it could be done as you want. Attention to detail would be the key I think (hard to fix afterwards).

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## pharmaboy2

It's not tricky, it just has to be done properly.  You'll want some architectural detailed drawings (not a drafty) and a quality builder.  It's really just a balcony over a living over a living Area but without the complication of the wall balcony interface, but instead will have a hatch as access - this will need flashing, raising above etc

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## world2160

I've been looking at different products as underlay. For example Scyon Secura from James Hardie - Scyonâ¢ Securaâ¢ exterior flooring | James Hardie 
These products all claim to be used on balconies over rooms. Have anyone used these and do they actually work over a long time (at least 10 years). The above suggestions are good but obviously sounds like it's going to add a lot more cost to my extension  :Frown:

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## pharmaboy2

I have done a balcony with compressed sheet, it lasted for 10 years with tiling over water proofing without any problems. I removed it as part of a greater renovation.  You need to follow the product guides to the letter - expansion gaps, proper sealants, flexible waterproofing suitable for exterior etc and drainage. 
of course it's more expensive, you have to weigh up the value of the rooftop though.  Your main problem will likely be council and neighbours though - amazing how neighbours assume loud parties with every change

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## wspivak

Hi world2160, 
It will work fine as long as you use quality construction materials, coupled with a good builder and an expert waterproofer who is using good quality waterproofing materials. 
The biggest issues I see with wateproofing membrane failures on balconies are almost always due to incorrect installation or poor building practices.

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