Deck with very limited clearance

Hi,

This is my first post, so be kind :)

We have a new house in Perth (mmmm sand), and I am wanting to undertake a small decking project attached to our house (out some french doors). Not doing anything like this before, I am keen to learn as much as possible ( the internet is a fantastic source of information, actually so is this forum ! ) I have attached a photo, as they say it says more than I could describe !

Anyway, the issue I have is my clearance - only ~ 15 cms, or two courses of bricks high. I am thinking this is too small a space to put in stumps, bearers joists AND decking ! As I understand, it is a good idea to have clearance for draining etc.

So what are my options ? I was thinking of something like a 'steel frame' frame construction out of something like steel square tubing, and mounting this somehow (maybe some posts attached to frame, then cemeted into ground - possibly attach one end to house ) But I dont know how the decking would go attached to this ? Would the frame expand/contract with weather, hence stress the attached decking finish ?

Ideas would be appreciated - I can post more photos if required. Thanks in advance

With the ammount of extra work you are describing I would give it a miss and go for some nice large pavers. Once down they would outlast decking and most importantly be far easier and less maintenance.
Jack ;)

Hi Archio

Welcome to the forum.

I remember being in the same boat about 8 years ago - new house, demolished garden and nothing but sand, and more sand .... and two retrievers that would be dragging sand into the house ..

Are you sure that you want a wooden deck? It is a lot of upkeep. We ended up building a brick deck. Ideal in Perth. Just a personal note.

Anyhow, I don't think that you have too little room for wooden joists myself. I would vear away from steel construction. Or is this just a choice of rust verses rot? No doubt you will hear from guys like Mick ("Journeyman Mick"), one of a few professional builders on the forum.

Regards from a fellow Perthite

Derek

hi Archio

you must have a minimum of 150mm (15 cm) clearance between any timber and the ground. Given that you only 150 mm to start with you would have to dig out 150mm of dirt which would create a hole for water to collect in.
Since the 150mm clearance is mainly to prevent termite entry you could possibly lay a blinding slab with termimesh under it the lay the sub floor framing to that. WAY too much work.
Steel sounds interesting but I have limited experence here.
Quite honestly I agree with the others pave the area,less complicated and much less maintenance

Archio,
Generally you need a minimum of 600 clearance to your lowest timber members. This is for access for termite and rot inspections and to prevent rot in the timber. There are some varieties of fungus that will attack timber unless it is well clear of the ground - looks like heavy spiderwebs that go from the ground up to the timber. Best bet is pavers or similar, but having said that I once laid a pool deck on joists that were fixed to sleepers which were half buried. I didn't want to do it, but the client insisted, I don't know how long the deck lasted but I doubt it's still there. Your local laws regarding clearance may be not as strict as ours seeing you have lower rainfall and sandy soil but you would have to sit your joists on buried bearers to get in at 150mm. Like Julian said, if you excavate under you'll just end up with a mosquito breeding puddle.

Mick

Archio,

I have laid decks on very small clearances in the past, including my current house but there are a number of caveats (big word that I can't even spell!!).
Option 1
Firstly you need a concrete blinding slab as described by julianx. Easy.

Then you can fix treated battens straight onto it, and decking onto that. Treated timber everywhere, termimesh or similar to prevent tracking into the house from places you can't see. The really hard bit in your case will be getting a proper fall in such a shallow depth, you don't want any water ponding underneath, and I always like to be able to clean out underneath as well...it's amazing how leaves and litter collect there.

In your case this wont be easy.

In a similar situation here I have used 130 x 30 "speed deck" decking which is held down with stainless steel batten screws. The two boards closest to the house are pinned with shorter screws and once a year or so I'll take them up and hose out underneath. Seems fanatical, but if your not prepared to do that don't even think about the deck.

Option 2 is also one I have used previously to some effect: Build "tiles" or pavers out of timber decking of your choice on a treated batten frame.

Lay a slab to a level which is the thickness of the deck below your intended floor finish (duh!).

Build squares of decking timber on a regular module. I like 450 as a module because you only need to screw battens at each end not an intermediate one.

Drop the squares in place alternating the direction of the deck.

Bolt a perimeter beam to fit flush with the deck and hold the modules in place, allowing space for drainage under it.

Hope that all makes sense..it can be a much "softer" finish than brick paving, and easy to maintain. If something valuable falls between the cracks you just have to pick up the "tile" and retrieve it.

Good luck,

P :D :D :D

I am about to show my grave ignorance here but anyway :)

To me that sand looks like anything but a torrential downpour would disappear in seconds, leaving the top dry......

I like the pavers idea - seems to lend itself to the construction of the home

This suggestion depends heavily on the overall size of it, but maybe you could build a raised deck - with say a 1metre square lower section at the door, then stepping up a further 15cms or so to a raised, U-shaped deck?

:)

I know it looks like bugs bunny is about to come out of the house, but you get the idea I hope

Archio, looking at the image of your home I would assume that it built with concrete slab floor.
In any case there is insufficient space to construct a timber deck without creating serious problems.
With a paved area remember to keep the level below the existing weep holes & to slope the paving (min. 1 degree) away from the external walls.

Thankyou all for your replys, I have learnt heaps over the last week about decks !

On the weekend, I went and spoke to a company in perth which constructs decks. I actually went there to have a look at modwood (mentioned on this forum before) because it sounded like an 'interesting' product. Anyway, didnt like the stuff at all ( it seriously is like plastic, looks like plastic, feels like plastic, damages like plastic !! ).

I asked the guy there about how they do decks like mine (limited clearance) directly off the house.

He said they clear out the area, compact it ( its sand all the way over here), and virtually lay a wooden frame onto this area ! Then the decking goes on top of this frame. He didnt say how this frame is fixed to anything though.

I have since spoken to another person, who suggested this would probably work. One of the display homes near our house has decking simular to mine. But they have put in a concrete slab, which a frame structure rests on, which the decking connects to that.

What are peoples thoughts on this ? I know alot of people have suggested paving, and we have taken this on board. Paving is used extensively throughout Perth (probably W.A also ! ), but we like the look of a deck. It must be possible, since we have seen several decks with simular clearance to ours. The Deck will be purely flat, for something like a day bed or some tables to sit on.

Oh, while I am asking, what is Batu like as a decking material ?

Regards

there is a product out that i saw on TV. its a gridlock system that has a 'tile' with a plastic base that locks into other 'tiles' and on top of it is timber slats. its laid over a concrete slab and the plastic base has drainage grooves in it. the tiles can be laid all in one direction or 'herringbone' effect. Not sure of the name and dont know who makes it. may be a solution to your height problem.

Archio, you are contemplating exactly what I am doing at the moment (in the big sandpit). Firstly consider access to services such as water, gas and soakwells. Midge's idea of timber tiles is good in this respect and does work. Anyway here's how it goes:

1. Scrape out to 8" deep, a bobcat helps but I did most of mine by hand
2. Plan and layout out your grid of framework which should be jarrah 4 x 2's
3. Did and install concrete pillars/foundations into the sand and don't use the rapid set cr*p. Install flush top stirrups for the 4 x 2's on the conrete.
4. Install the framework and put in 3 or so inches of blue metal which almost comes up to the bottom of the frame work.
5. On goes the deck

Consider having the area treated for termites, most of the concrete guys can do this for you.

Consider additional drainage from the area. AG pipe etc??

We have had this arrangement down for 20 years in Kalbarri and it has been superb. I actually had to pull up a section to connect to the deep sewage but whilst it took some work it was acheivable. I assume you are talking about decking with gaps between the boards, this lets the sand fall through and is heaps better for keeping the house clean than paving or concrete.

Pre-paint the framework before you put it down.

Cheers

OK !

I have taken everyones advice on board, and started my deck contruction last weekend.

I ran 90x45mm bearers in the ground (coated with Cresote), 70x35mm Joists then ran 500mm apart sitting on top. I concreted in extra support for the bearers, and the whole thing is attached to the house.

( I will post photos tonight, have to wait for my camera to charge )

Hope I have done everything right - the guy who put up my patio said it looked good, and thats how they do decks like mine over here.

The sand really offers very good drainage, but I will put some crushed bluestone around anyway.

So, I now have 42 peices of Batu decking. I was supplied self-countersinking galvenised screws. I have been told I need to predrill, and then screw in.

My question is : How flush 'should' the screws be to the top of the decking - I have tried on some test batu, but it didnt countersink very well, sat up ~ 1mm. Admittably the drill bit I have was 'crap', and probably so was the drill. But do people predrill, countersink and then perhaps finish it off with something else ?

Advice appreciated :)

Hey Archio,
re countersinking of screws, you can purchase a combination drill and countersinker from most hardware stores. This means as you predrill you are also countersinking. I have found them handy when screwing down harder type wood, and i leave my screws just a touch under level with the board.
Cheers, happy screwing!

Or you could buy a countersinking bit that in effect makes a shallow but wide hole so that the head of the screw doesn;t have to push through the wood. Self-countersinking bits only work well in softwood or if you give them lots of downward pressure.

You could always just nail it down - usign galvanised twist shank nails of course!

Trav