Constrution of Timber Deck

[HAMMER]

Hi, I hope some one can help out on this, I am wanting to build a double car garage onto the back of house with a timber deck on top. I will be using Tongue and Groove Hardwood decking. Can I use fibre cement sheeting and maybe run 40mm battens and then decking on top with a sealer finish. Roof cover 1/3 of deck, so it will be exposed to the elements. What would be the best way to construt the roof of this garage so that it is water proof. I have had 80% of builders say that it can not be done and to use tiles and not timber??????

:( :confused:

[Sir Stinkalot]

I think the problem will be the external use of t&G. I dont think that the fibre cement sheeting will qualify as a suitable water proof membrane. If the deck is to be t&g how do you expect the water to flow off?

[silentC]

I can see a number of problems with that approach but the main two are:

1. How will you attach battens and a deck to the roof without penetrating the membrane?

2. If it leaks, which it probably will, you wont be able to access the roof to seal it because of the timber deck.

Even the tiled jobs are difficult to get water tight. You'll need to use a water-proofing membrane over the cement sheet to stop it from leaking and once you've applied that, you wont be able to fix battens to it. You might be able to fix the battens first but then you have the same problem when fixing the deck. The T&G wont keep the water out.

I've seen it done with a tin roof, then a deck cantilevered over the top but what do you do when the roof needs replacing?

It probably can be done but I'm not sure if it's a long-term solution. If I were you, I'd go with the tiles. Think of it like a bathroom floor.

[bitingmidge]

Don't do it!!

Apart from the reasons set out above the t&g will move when it gets wet. It will move so much that it will lift some boards, crack, split warp fade and peel and probably rot as well.

You can use a fibre cement sheet, suitably waterproofed, then batten timber over the top if you wish. There was a recent thread regarding building a timber deck over concrete (http://www.woodworkforums.ubeaut.com.au/showthread.php?s=&threadid=7227&highlight=timber+concrete+deck) which may help.

At the end of the day, fibre cement, flashed waterproofed and tiled will probably be the least expensive, but I like the look of timber personally.

Cheers,

P