# Forum Home Renovation Waterproofing  Waterproofing enclosed balcony

## paddyjoy

Would appreciate some waterproofing advice on this, I will be getting a professional in to do the waterproofing membrane however need to check I'm doing all the prep right. 
We are building an enclosed balcony, see pic below.   
I'm planning to install sycon external sheets. I have cut the joists  down so there will be a height difference of 50mm between  inside/outside. When I cut the joists out I also included a 1/100 fall  towards the back of the house. 
Obviously there is no option to run off the water so it will need to be captured. I assume a puddle is minimum standards for a situation like this? using a cup grinder to recess the flange below the surface of the sycon? 
We would really like to have a timber deck floor rather than tiles. Are there heavy duty membranes available that can have a timber decking panel type thing sitting on top without getting damaged/penetrated? or would I need to apply a layer of something on top of the membrane to protect it first?

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## Random Username

I would say reconsider the entire design. 
50mm/1:100 slope is really a minimum - and that's assuming the fall goes to an open edge. 
If it's totally enclosed you want to give the largest incentive possible for rainwater to move towards the drain, otherwise in an extreme downpour event it could behave like a kitchen sink with a bucket of water dumped into it.  And if you are putting extra stuff in there - like a timber deck and supporting timbers - you've reduced the water holding volume by the volume of that extra material, so you have to allow for that too. 
What size drain are you looking at for it?  Remember that extreme rainfall events have been increasing in number and are expected to keep doing so, so it will pay to think big!

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## phild01

I would be particular about the drain you use to avoid any blocking.  One drain I saw, and it surprised me how well it worked in a heavy downpour, was a full length channel about 20mm wide on a large driveway area.  The holes in it looked about 12mm in diameter every 100mm or so.  Think it was a plastic custom thing, anodised aluminium U channel would work well.

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## paddyjoy

> I would say reconsider the entire design. 
> 50mm/1:100 slope is really a minimum - and that's assuming the fall goes to an open edge.

  Thanks I don't disagree with you, if I could go back and redesign this I would however at this stage the only changes I can make would be to put a roof over it! I didn't spend enough time thinking this part of the design through, big lesson learnt here. When I was building the floor I ran continuous floor joists from the front to the back of the house, this means I am limited in the amount that I can notch out and subsequently slope the balcony. It's a real pain and it gives me nightmares ha ha   

> What size drain are you looking at for it?  Remember that extreme rainfall events have been increasing in number and are expected to keep doing so, so it will pay to think big!

  I'm planning to use a 100mm puddle flange with 100mm pipe, it's pretty big for an area that is only 2m2 however I want to be sure I'm covered in case some leaves or other debris gets blown into it.    

> I would be particular about the drain you use to avoid any blocking.  One drain I saw, and it surprised me how well it worked in a heavy downpour, was a full length channel about 20mm wide on a large driveway area.  The holes in it looked about 12mm in diameter every 100mm or so.  Think it was a plastic custom thing, anodised aluminium U channel would work well.

  Thanks I have seen these before. If we decide to tile the floor then I'll definitely use a strip type drain like this.

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## Gaza

Maybe add an over flow with a pipe just below the internal floor height   
Sent from my iPhone using Tapatalk

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## phild01

Rather than notching, what about ripping some long thin wedging.

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## paddyjoy

> Maybe add an over flow with a pipe just below the internal floor height   
> Sent from my iPhone using Tapatalk

  Thanks Gaza that's actually a pretty good idea  :Smilie:

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## paddyjoy

> Rather than notching, what about ripping some long thin wedging.

  Problem with the wedges is that I wouldn't achieve the minimum step down. I did all the notching yesterday, pretty laborious, even with two of us took the full day.

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## paddyjoy

So had to plough on with the current design, have the flooring cut and recess for puddle flange.  
The difference between floor levels is going to end up about 60-70mm, was the best I could do unfortunately 
Does anyone know what would usually happen to close the gap between the floor levels, do I need to install a piece of angle or does the waterproofer look after this?

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## Random Username

Personally, I'd just run a bit of timber along there (filling any overhang from the sill) as it's going to be on the dry side of the membrane.  I think it'd be more important to make sure the sill has no room to flex and to have a reasonably easily observable area to watch for water damage.

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## paddyjoy

> Personally, I'd just run a bit of timber along there (filling any overhang from the sill) as it's going to be on the dry side of the membrane.  I think it'd be more important to make sure the sill has no room to flex and to have a reasonably easily observable area to watch for water damage.

  Thanks that's definitely a simple solution, that sill is going to be the weakest link. 
Would it be safer though to run the membrane up behind the sill like below?

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## phild01

I would use the tilers plastic angle flashing (approx 50x75) adhered down with fullers 303 then waterproof  http://www.mbssandcement.com.au/pvc-...ng-75mm-x-50mm
Fulaprene 303â„¢ | H.B. Fuller Australia

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## paddyjoy

> I would use the tilers plastic angle flashing (approx 50x75) adhered down with fullers 303 then waterproof  http://www.mbssandcement.com.au/pvc-...ng-75mm-x-50mm
> Fulaprene 303â¢ | H.B. Fuller Australia

  Thanks Phil, going to use angle but aluminium as you will see it between floor and sill. Waterproofer is happy membrane will stick to alu.

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## phild01

> Thanks Phil, going to use angle but aluminium as you will see it between floor and sill. Waterproofer is happy membrane will stick to alu.

   :2thumbsup:

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