Joists on concrete.

[Tandum]

We have a bit of a patchwork of concrete out back, some is stamped and red, some is plain old wood floated, some has pavers on it. A lot of it is stained with paint and crap.

I'm considering plonking hardwood decking over all of it but what sort of joists should go under it. I'm guessing treated something but treated what and how should the joists be fixed to the concrete? Glue, concrete self tappers or both? Any experts out there :)

[leon]

Treated pine Robin, A couple of dynabolts, and possibilily some liquid nails should do the job nicely.

Leon

[h0ughy]

h4

[Tandum]

Cheers leon, there will be water around the joists when it rains but I guess if the treated pine fence can handle it then it should be ok. The frigging flooring is really expensive, I need to get it right first go :)

Dave, what is h4? A wood grade? Ok found it, hazard class 4 treated pine.

[h0ughy]

yep its more durable in and above ground - just paint the ends when you cut it to save water egress - nothing is ever rot proof

[Tandum]

Cheers Dave, now I can try and price it, looks expensive :(

One other thing, anyone know what a biscuit cutter is when talking wood. Apparently a biscuit cutter cuts a thin slot along the long edge of timber. Then you can use a fixing system that does not require nails or screws through the floor boards. A tag goes between the boards, fits in the cut slots, and the tag is screwed down. The boards are also glued to the joists.

[Tandum]

Good old google :)

It's called a biscuit joiner -> http://en.wikipedia.org/wiki/Biscuit_joiner

And $100 from Bunnings (http://www.bunnings.com.au/products_product_joiner-biscuit-ryobi-600w-ebj900rg_P6210328.aspx?search=biscu it+cutter&searchType=any&searchSubType=products).

[Kunama]

In the weather conditions you have in Brissy I would be inclined to nail the decking down to the joists with twist shank nails. I would also use a galvanised plate under the bearers to keep a small gap under the timber.

With hardwood decking I also predrill the boards to prevent splitting especially anywhere near the ends of the board. With a 90mm wide board I nail 15mm in from each edge on every joist. Use galvanised nails and remember to paint or varnish the underside of the boards before installing to prevent the timber 'cupping' ( if only top is stained/coated the underside swells and then you have cupped boards that hold water and then the mould sets in.) Also stagger your joints unless you have long enough decking to go through in one piece.

Many use treated pine for joists but treated hardwood holds the nails better when the sun hits the deck and tried to ruin all you hard work.

[astro_nutt]

A dab of bituimn paint on the cut ends and dip your nails in before hammering them in also helps.
Cheers!

[Tandum]

Cheers guys. It's looking to be really expensive to cover everything, even just doing the undercover area which is about 33M2 is looking to cost da bomb. Might just be a can of paint yet :)

[Kunama]

That would be my recommendation, a good acid wash and Berger Jet Dry Paving Paint.

[alan meehan]

concrete paint Robin is the way to go is cheap enough and much easer than a deck ,even if you use treated timber it can get damp and after awile will rot
gal steel is much better but more expensive
if you can find a concrete supplier they will have a range of concrete finishes
AL

[ZeroID]

Why not support your beams above the concrete ? Build a squarish frame, mount it on pavers with some water proofing beneath. Pier is secured down to the concrete and you have an isolated floor around it.
Works for my SkySlab Ob ( hence the name )
Solves your possible damp problem. Only needs an inch or two lift.

[doppler]

With that much "bits of concrete/ pavers"' a builder would rip the lot up but if the concrete is stable ie no cracks or movement you could just bolt down some joists and put on the decking.

[Tandum]

Yeah guys you can do it lots of ways but hardwood costs about $50 a square meter plus just for the decking. Add the supports, metal fixings, nails, tools etc etc etc and you're looking at $65 a square meter minimum for material if you buy cheap crap off ebay. There must be better options. I can tile it for less than half that.

If we where building a new one from scratch then maybe. I'd rather spend this cash on a new mount to be honest :)

[alan meehan]

Robin splash some paint down then buy a new mount,thats the way to go
AL:thumbsup: