Pine decking on existing concrete slab

[gideOn]

Hi ppl,
I currently have an existing concrete slab (6m x 4m) and wish to cover it with 90mm treated pine reeded decking.

Qns:
1) Support batton dimensions? (was thinking ~ 40mm x 20 mm?)
2) Support batton spacing?
3) Fastening of battons to concrete slab?
4) Fastening of decking to battons?

The slab is currently covered by a gabled patio roof, and as such is protected from the worst of the weather, and only gets late afternoon sun

thxs in advance,

gid

[Sir Stinkalot]

There was some questions raised about this a few months ago. (I think that I asked :))
One of your problems will be when small things (credit cards, coins, food, dirt, leaves, etc) fall between the decking boards and become lodged between the deck and the slab. They cannot be removed.
Waterproofing of the batterns will also be an issue. They will need to be raised above the slab to allow for drainage off the surface of the slab.
Try doing a search (button above) for decking over concrete or the like as I recall there being a few different approaches used and some suggestions from users that have tried.

Stinky.

[seriph1]

[B]Hi ppl,
I currently have an existing concrete slab (6m x 4m) and wish to cover it with 90mm treated pine reeded decking.
Qns:
1)batton dimensions?

35mm square treated pine or similar, but what you have suggested will work - just make sure you use fixing nails that are long enough to make it all secure, and short enough so they don't go through both decking and batton and bend.

2) Support batton spacing?

450mm centres

3) Fastening of battons to concrete slab?

RAMSET, or: masonary drill, rawplug and screw

4) Fastening of decking to battons?

galvanised nails

Also, you probably know this but just in case..... the reeded side goes down, not up - mistake people often make. Agree with the "lost stuff" concept and this can be adressed by having a pair of screwed decking planks every so often, instead of all nailed.

Finally, builders seem to use a 2 inch nail as the way of spacing the boards, for those that want a space between them.

Cheers

[Thommo]

Hi Gid,

Have a think about using 90mm merbu

We had the pine decking and the stuff they put out now is rubbish

We pulled it up after 1 year and replaced it with merbu.
Heaps stronger and doesn't move nowhere as much as treated pine


Cya Guy

[seriph1]

I didnt wanna wade into this debate, though agree about not using treated pine - it is probably the cheapest stuff around, but I personally prefer merbau or similar too.

Being undercover would help the treated pine a lot though.

[Trav]

what about looking at recycled timber for your deck?

I only say this because I am about 40% through fixing the timber boards for my deck. I sourced some recycled blackbutt cut from old joists and bearers. It was about the same price as merbau (approx $50 sq mtr) and it looks fantastic. It is a bit more 'rustic' though (has old nail holes etc).

despite comments in another thread, I am a little concerned about the sustainability of merbau - a lot is harvested from tropical rainforests etc. While I'm not a tree-hugging hippie, I figure that anything we can do easily to stop logging in these areas would be good. Plus, everyone knows that aussie timber is the best...:)

Over your way I reckon you could pick up some great old jarrah for a deck - similar colour to merbau but stacks better.

my 10c worth

Trav

PS keen to hear which way you decide to go with fixing the timber. I have a similar situation and, after reading all the threads on it, decided to just paint the concrete. It seemed to me that the overall feeling was to demolish the concrete - not an appealing thought for me!

[seriph1]

agree - Jarrah decking kills!

[Geno]

Avoid treated pine decking like the plague. I can think of no redeeming features of the stuff apart from price, but even that is a false econmy as you will have to replace it in a few years. Looks like crap and moves to all buggery.

Seriously consider getting some decent recycled timber (as Trav has said). Failing that go for merbau (preferably responsibly sourced). You won't regret it, she'll look tip-top!

[gideOn]

Hi ppl,
To begin, let me thank everyone for their prompt and informative suggestions. It seems I have a number of things to consider before I proceed.

Some information I (foolishly :-/ ) did not include in my original post:
The concrete slab in question is actually a suspended slab, forming the roof/ceiling of a bedroom on the ground floor.
The reasons for wanting to install the decking are 2 fold:
1) aesthetics (current painted concrete look is ........ errmmm ... well painted concrete!)
2) to provide some heat insulation. Even with the gabled patio roofing as cover, the late afternoon sun heats up the slab, making the room below uncomfortable... especially with a run of days with temps in excess of 35C

With this in mind, would the dark woods (jarrah etc) heat up more and lessen the insulation effect? I don't want to make the joists too tall (increasing the cavity between decking and slab) as this slab ajoins the rear first floor patio, and a large step would look out of place.

thx again for all your help,
regards,
gid

[silentC]

Have you considered tiling it?

[Trav]

gideOn

sounds like you are going to have to step down from your new deck into the house. Is this right?

You would want to be pretty careful doing this as you could end up with a loungeroom full of water.

I guess jarrah would be hotter, but probably not all that mugh hotter. By the time you paint/stain pine (which you would need to do to protect it as it is really soft), it would be resonably dark anyway.

Have you thought about insulating under the slab? ie hanging a ceiling if you have room and then insulating with bats or with that foil stuff (as you can tell, I'm not an expert on insulation)?

Another thought would be to put up some kind of shade sail. Hard to tell if it would owrk in your case, but it would keep the sun off the roof for much of the day.

[Trav]

seriph

would you just use normal (galvanised) screws to fasten the battens?

Also, what would happen if you packed the boards close together (ie no gap), but on a slope sufficient to encourage the water to run-off quickly? This could get around the hassle of dropping cash, creditcards, dirt etc down under the boards.

Trav

[seriph1]

I wouldnt worry too much about galvanized for the battens, as they will be permanently covered and theoretically out of the rain.

Regarding the gaps, if you arent going to have a gap, then I am uncertain if decking is the best solution - perhaps floorboards may be the way to go..... I feel it would be rare that something as important as a credit card would get lost but it is possible....but couldnt you just "sweep" it out from one end?

I feel sure that if something extremely important was dropped, a way of retrieving it would be found, even if it came down to removing a single board.

Like I think I said previously, a screwed (stainless or gal screws)board every so often would solve it, if you wanted to go to that extent.

Success, Steve

[journeyman Mick]

The gap beween the decking and the slab will help somewhat with the heat even if the boards are quite dark. ( Think old land rovers and permanent site caravans in hot climates, they often have a second roof fitted over the existing with an air gap between- called a tropical roof). If the decking is exposed or semi exposed it will need to be laid as decking (ie with 3mm or so gaps between boards) rather than flooring, unless of course you want to see what walking on water might be like as the flooring will develop wave shaped buckles. Don't even consider using bright steel or zinc plated fasteners as even with the shelter of the roof it's still semi exposed and how much is it going to add to the cost to use gal fixings? Use 50 or 65mm gal bullet head nails, battens at 450 centres, laid on a generous bead of polyurethane sealant (Sikaflex, or Bostik Matrix or Seal & Flex) with mechanical fasteners at 600 - 900 crs. For battens I'd use 70x35 on edge, or if the height was an issue rip down some 90x45. If the deck ends up being higher than the inside floor I'd ramp the end of the deck down over the last 5 - 10 boards (depending on the height difference). As far as dropping stuff between the gaps is concerned, make the first board removable so you can poke a hose in and flush everything to the outside edge. My 2.2c worth.

Mick

[bitingmidge]

Another solution is to simply make a heap of "tiles" in whatever decking you choose; simply make squares of decking of a suitable size (say 600 x 600) and loose-lay them in alternating directions.

I'd screw them from the underside with stainless screws, but you could just as easily use nails or staples. Fixings from the underside will give a nice clean finish.

Use small rubber grommets or a bead of silicone to take up any slight variation in the slab.

Fix a perimeter border around the whole deck, and you can take them up individually to clean and maintain. This has the added advantage of allowing you to oil/finish the underside each time as well.

I am about to do exactly this with our shower floors: any suggestions on timber species?

I had originally intended to use Western Red Cedar for durability, then thought "it's only water" (!) and maybe almost any thing will do the trick if it's maintained well enough?

Merbau? Beech?

Cheers,

P

[silentC]

Or you could tile it.

No height problem, no water problem, no lost keys, no stuff growing underneath, no mould or rot if the drainage isn't right, no weathering (well, that depends on the tile). Insulation? Probably negligible. Put some batts in the ceiling of the room below. Don't think a timber deck is going to help much there anyway.

Probably even be cheaper too. Last time I looked you could buy tiles for under $60 a metre.