Floor for external balcony

Hey

As the name suggest - I have no idea.. Hoping someone can help.

I have a external 3m x 4m terracotta tile balcony on the 2nd level of my house.

Problem is it has been leaking (only in heavy rain) for the last 2 years and damage has been caused on the ceiling below.

Contemplated "sealing" the balcony but have been told by so many people its a quick fix and unlikely to last. In any case my water problem looked a bit more serious.

Last weekend I ripped up the tiles and the membrane. 5 hours on the end of a kanga hammer and 750kg of tiles/cement later I was left with a substrate of compressed fibre sheets. Unfortunately (although maybe a blessing) I have created a couple of fist size holes where I had been two keen with the kanga. On close inspection of one of the holes I could see part of the joist - Wouldn't you know it.. its 1/2 rotten.

So it looks like I'm going to have to rip up the existing fibre sheets, get some of the joists/bearers relaid and new sheets put down.

Its at this point I decided to call in the professionals.

Had two builders come look at the job today.. Both independently have recommended using a James Hardy product (with tongue and grove) for the substrate. They said it is much lighter and easier to nail/fix than compress fibre sheets.

http://www.jameshardie.com.au/Products/Flooring/ScyonInteriorWetAreaFlooring/

I've done a bit of googling and this appears to be the product they are talking about

Problem is it says this should only be used internally...

I'm going to get a waterproofing membrane over the floor and then re-tile but am still concerned that their suggested solution is not the correct one.

Should I use these Sycon sheets externally (plus waterproofing membrane)? Or should I insist on them using Compress Fibre Sheets.

Could of they been talking about another product? Were these builders trying to cut corners and make the job easier for themselves...or is it a suitable option?

Any help appreciated.

This is not the kinda of thing I want to do twice.

First I'll start by saying I can't answer your spcific question but I wanted to describe my exact same situation.

We bought a house last xmas and when the rains came we discovered leaking into the downstairs from the upstairs deck.

I hired a demo hammer and lifted all the tiles (36sqm) and then spent a day in hospital with a racing heart courtesy of the using the hammer.

I hired a concrete mower to remove all the mortar and returned the sheeting to a smooth service.

I located the damaged areas and on lifting the sheeting I discovered the rotting joists and bearers underneath.

I called the pros and they replaced the timbers and cement sheeting.

I can't say what they used it appeared lighter and less dense than the original, they nail gunned it rather than screwed it, it was tongue and groove, similar to the link you sent. So it may have been the same.

I then applied a membrane (Bostik Ultraseal) laid battens and another coat of membrane over the battens, then laid decking boards.

Fingers crossed this will last for a while.

A previous post shows the old and new deck, and the photo below is the completed product with some furniture.

Cheers,

https://www.woodworkforums.com/showthread.php?t=57362

Simple - follow manufacturers advice and use compressed sheets - the Sycon is for internal use only and will lose any guarantee if used externally as in your deck (and contrary to specs).

See:

http://www.jameshardie.com.au/Produc...llationManual/

This stuff is easy to install and there are various levels of sealing during construction to provide water resistance up to fully waterproof.

Most likely you will need only to replace joists that are under joins in the original and possibly by simply adding new joist adjacent to the existing one rather than removing the old ones.

If the ceiling underneath is accessible and plasterboard you might be better to remove it to inspect what state the joists are in - if they are mostly OK then you could re-sheet over the existing fibro sheeting.

Depending on the age of the deck the sheeting might be asbestos - quite safe so long as you do not drill, cut or sand it, but a good idea to have it removed safely anyway (and each state has rules about who and how).

It ought not to be too hard a job though - if the existing sheets are screwed or nailed then you just remove one row of sheets at one end, do the needed repairs to joists and place new sheeting back on then do next sheets working of the new ones. Following the instructions for edge joint sealing and then you can use a brushable urethane membrane over the top when all sheets have been replaced.

Summary - do not use sheeting designed for interior work regardless of a tradey saying you can - it means that you then rely on the membrane when in fact your should have a complete system that gives you the service life and performance you need for exterior use.

That sums it up nicely Bloss. You'll void any warranty, implied or written, if manufacturers' specifications are not complied with.
It may be highly unlikely that you'll have any problems, however if it was guaranteed, then Hardies would sell the sheets for external use.

I know who I'd rather be chasing if I had a failure somewhere down the track, and it's not some builder who may be bankrupt, or unreachable by that time.

I am a bit confused about this Scyon sheeting. I read the tech data posted and yes it says "internal". But they use thinner Scyon panels for facards and general external walling. I might phone Hardies on Monday to find out what they say. I'm curious myself.

It's certainly much easier to use, being lighter and nail fixed.
It would be more porous and less waterproof than compressed though. If the membrane does get punctured or scratched by a tiler, I'd rather have compressed under it, but then again a shower recess would see a lot more water than a deck.
I don't really know what their reasoning would be. :?