Laying 19mm Floorboard - Over Existing or on Joists??

[learninglots]

We're renovating a century old Queenslander.

Sadly, the old baltic pine floorboards are stuffed. There are largish holes through to downstairs, wide gaps of up to 10mm between boards and large areas that have been replaced with mismatched boards (wrong width and all!). Its also about as level as the tasman sea. To top it off there are a few areas of wet rot.

We knew it when we bought the place so don't feel too sorry for us.

My question is - what is the best option for laying a new 19mm end-match T&G floor (80mm Redgum)? The options are:

1. Level the existing floor as the house is raised as best as possible, then lay the floor directly on the old floor (I'm a bit concerned about the wet rot in this case

2. Rip up the old floor, put down marine ply base then new floor over

3. Rip up the old floor, put the boards directly on the joists

4. Another Option I haven't thought of.

Also, should this be done early prior to other trades, then covered to be finished near completion of other work, or should it all be done near completion?

Any advice is much appreciated.

Plus any ideas of good floor tradies in the Brisbane area.

[Skew ChiDAMN!!]

3. Rip up the old floor, put the boards directly on the joists

1. Laying over the top is doubling the load on the joists, which ain't as young as they used to be. And you're right to be concerned about covering over wet rot. Remove the old boards and use them to keep warm or roast a few spuds in foil. Give the exposed joists a good inspection and replace any that look suspect.

2. Depends... If you're going T&G then why bother going to the extra expense of a sub-floor unless you have good reason?

3. This would, IMHO, be the way to go, provided the joists are a max of around 600mm apart and of suitable size. (I imagine they would be.)

4. You could go the ply underlay and slap laminated/engineered boards on top. I prefer the look of old T&G myself, but that's just my personal preference.

[glock40sw]

G'day.
To fix 19mm T&G directly to the joists, they have to have 450mm centres.
If it is more than 450mm the floor will bounce.

If they are 600 centres you will need to use 25mm T&G boards or install 19mm Yellow tongue to the joists and them glue and nail the T&G to the Y/Tongue.

It is all in the data sheets at www.timber.net.au/downloads

get the flooring data sheets.

[learninglots]

Thanks for the replies.
I'll go with pulling up the floor. The existing subfloor needs reinforcement, which I've already planned.

Cheers!

[Connollys]

Pull up the old boards, level and replace any rotten or damaged joists, then lay yellow or red tongue before laying the new boards.

Cheers

Craig

http://www.connollys.com.au