Fixing bearerless deck to slab - best way?

[brisbaneg]

Hi,

I'm planning on building a ground level deck atop of the slab in my courtyard. Picked up some great tips so far on the forum, especially the one where somebody linked to a PDF explaining building a low level deck using only joists.

My concern is how to fix the frame to the slab. Obviously I can't put down stirups. A guy up at Bunnings suggested chopping some H4 Grade 90x90 and using it as spacers under the joins (using 90x45 H3 for the frame) but as to fixing it down, didn't have much in the way of options.

I have only 8cm clearence between the lowest point of the slab and the door (!!) which is kind of complicating the issue.

Could somebody suggest an option here? What about using some sort of galvanized strap, bend in an n shape over the frame and dynabolted to the slab?

Any ideas appreciated..

[Dusty]

Here's one I worked on a couple of weeks ago, where I had to replace a few boards, giving us a clear look at what is underneath. It might help in some way.

Good luck.

[addo]

A bit O/T, but I've not seen a template before like you have there (that which looks like a reinvented chopping board). How is it used?

Regards, Adam.

[DJ’s Timber]

A bit O/T, but I've not seen a template before like you have there (that which looks like a reinvented chopping board). How is it used?

Regards, Adam.

That looks like one of those mats that you use for kneeling on, not a template

[pawnhead]

It looks like a piece of mdf that's had a lot of use for something or other.
I'm intrigued now.

[Dr - 307]

brisbaneg,

A guy called 'utemad' does alot of this deck on concrete stuff. From what I've read you need to work out what clearance you have left after substracting the thickness of the decking board. Then work out what section size timber you can fit as joists and space accordingly as you would any other floor. As far as keeping the 'joists' off the floor he suggests 'horseshoe packers' which is a plastic packing material. It's easily drillable and you can build packing thickness up to whatever you like as they come in 1mm - 10mm thickness as well different size dimensions. Whatever sectional size of timber you are using as 'joists' you'll need to countersink the galvanised (don't know your knowledge base) dynabolt flush into the timber so it doesn't interfere with the laying of the decking boards. After that it should be just laying the boards either by nailing or stainless steel screwing.

Cheers,
Dr - 307.

[brisbaneg]

Hi guys. Thanks for the multitude of responses!

dusty - nice looking deck. Those L shape brackets would be ideal...

Dr - 307 - thanks. I read a few of utemad's posts. the one about the horseshoe packers sounds like a reasonable idea. much easier & less likely to rot than timber. I'll check them out.

as to my experience level, which way do you hold a hammer again kidding not quite that bad hehehe

Here's one I worked on a couple of weeks ago, where I had to replace a few boards, giving us a clear look at what is underneath. It might help in some way.

Good luck.

[Dr - 307]

That's good. You'll find that you'll get to know the usernames and their experience level as you go along. Welcome brother brisbaneg.

[pawnhead]

I reckon that you could forget about the brackets and just skew screw the joists directly into the crete, using 4" long square drives into spaghetti.

I've done this myself before. Save a few bucks, and solid as a rock.

[Dr - 307]

What about water and rot over time? At least some packing / air underneath req'd surely?

[addo]

Pack as needed, and slip a little snakeskin under the bottom packer.

[Tubby2]

I have just done this on my front porch and my back verandah.
I dyna bolted H3 35x45 straight to the concrete and then screwed my decking ontop. I expect it to last at least 10 years. I spose putting fibro packing under the battens would make it last much longer.

[pawnhead]

What about water and rot over time? At least some packing / air underneath req'd surely?

Nothing wrong with skewing through a fibro packer sitting on snakeskin.

edit: It would be strong enough, and you wouldn't have to muck around with a heap of more expensive dynabolts, socket wrench, and drilling two holes in the timber to get a deep enough countersink for adequate slab penetration, and another masonry bit to do the slab. One bit does the lot with spaghetti, but you'd put two in as opposed to one dynabolt though.