A little Deck Project - my first - eeeeek!

**BronteDave** · 25th May 2011, 05:07 PM

Hi all

I've been lurking here for a while but now taking the plunge and exposing my clear lack of knowledge in all things woodwork related - but on a mission to build a ground level deck that's been in the planning for years now.

Where better to ask for advice than here?

So, here's the summary. I have a U shaped area bordered by an existing paved patio (left), my house (top) and a paved pool area (bottom). See attached sketch. (Grey area is planned decking, yellow dots are planned lights, decking to run from top to bottom)

I've decided to incorporate both a sand pit and a garden bed into the design which means I've ended up with a non-simple design (i.e. not a straight rectangle but a couple of rectangles and a bunch of offset squares).

So, some initial questions to get the ball rolling

1. How far do I have to dig down bearing in mind that I'd like to build with my joists on top of my bearers and use post brackets (rather than bury my posts into the ground)

2. I've read of some designs recently where the entire deck is built (or at least the posts, bearers and joists) prior to the posts being set into the ground. The post brackets (is that what they're called?) are then suspended in the holes and concrete poured in around them. This sounds like a good idea. Anyone?

3. What size timber should I be using for my joists and bearers (I know it depends on what span I am after but to be honest, that's less of an issue). What is the standard size that people would use for a fairly small (e.g. 5m x 2m ground level deck). (Once I know this then I can work out what spans I am allowed using span tables - right?)

4. What type of timber do I need? I haven't a clue about strength ratings and/or treated ratings

5. Where do I buy timber from? Bunnings only has a limited range and I guess is fairly pricey compared to the yards? Any recommendations (I am in Brisbane)

6. Has anyone used modwood for decking? Any good compared to hardwood?

7. I'm in Queensland - does anyone know of any special conditions around building low level decks? It's fairly small so probably doesn't need Building or Planning Permission? Maybe?

So as you can see - while I have lots of passion I am fairly clueless in technique - so if anyone can help I'd really appreciate some tips and pointers (even if it's 'go read this article').

Thanks all
Dave

**Astrodog** · 25th May 2011, 09:35 PM

I'll answer a few of your questions....
1. Can't go wrong with 600mm - but you may need to consult local regs.
2. Good idea - I did this for a small observatory a few years ago - build the structure and then suspend over your pre-dug holes, I used a few car jacks to level everything up, then our your concrete - works very well.....
3. Depends on span and the timber you want to use....
4. I myself would use some nice kiln dried hardwood for the frame, and some hardwood flooring, will cost a motza more than treated pine, but will look much better....
5. Check around timber yards before Cunnings - this goes for most woodwork supplies too!
6. never used
7. ?? you may need to check your local planning regs - there will probably be a deck area and height limit above which you would need a permit.

Nice design.... I like Pryda's "high-wind" anchors for post support - you can bolt straight to the bearer too. Link to catalog

**BronteDave** · 26th May 2011, 06:09 PM

Thanks so much for that Astrodog.

1. Is that 600mm below ground level or below the lowest bearer?

2.Excellent - will give that a go

3. Since the entire frame will be hidden I think I'll go with treated pine. Is there any recommendations on what size (and I'll work out the span from there)

5. OK - Timber yards here I come ... eeeek not even sure what I'm asking for

Thanks for the link to Prydas catalog!

Regarding ventilation underneath ... does enough air flow through the gaps in the decking boards or do I need to ensure airflow from the sides of the deck as well?

Thanks!
Dave

**Astrodog** · 26th May 2011, 09:27 PM

1. Below ground mate, a petrol auger is a good hire investment!
3. Work out spans for 140x45 or 190x45mm pine - I've emailed my Brisbane builder father for spans for you....
5. have a look around at Cunnings first, suss out what you want and learn some terminology, then you won't look wet behind the ears at the timber yards!....
Decking - hardwoods - things like Blackbutt/Spotted Gum/Grey Ironbark etc all look great.....

Decks are usually open around at least an edge or two? I wouldn't think airflow will be too much of an issue....

**justinmcf** · 26th May 2011, 09:34 PM

hi dave.

with regards to planning permission.

any construction works carried out within 6 metres of the main structure (your house) requires planning permission.

you should call you local council to confirm this.

dont take my word for it.

regards, justin. (licenced builder)

**MrShuffles** · 28th May 2011, 02:01 AM

Hi BD,

I am a structural engineer and offer my two cents worth.
Recommended depth of footing to minimize movements depends on soil classification that is type of soil re movements with moisture change (sand stable but clay moves to varying extents so have footings deeper.)
Council should know type of soil likely in your area and could advise on this. There are geological maps of soil types.

I would suggest kiln dried hardwood for the bearers and joists for durability.

Consider merbau or jarrah battens for deck, both very rot resistant.

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