Feedback on decking project

[nmilne]

Hi all ... I'm just contemplating my first decking project at my home, as I have a large rear area on the house that is currently unused. My woodworking and joining skills are best described as basic but a decking project seems like quite an achievable thing to undertake, and should keep my bike motors together for longer as a bit of a diversion

To keep things interesting, the area that I want to deck in isn't square but is a sort of half octagon shape (of sorts) and there is an existing small balcony/staircase leading down into the area that I'm hoping not to tear down and replace. Oh, there's also a rather large tree in the middle of the decked area that I want to deck around

I've been doing a bit of reading around this site and others about timber sizes, however without being particularly experienced in this area I wanted to get some feedback on design and timber types/sizes before I confuse myself too much. I've drawn up some basic plans and have an approach:



The grey area in the design is the wall of the house. The brown/yellow section is a small balcony with handrail that has an angled staircase descending into the garden are (and inconveniently into the space I wish to deck ). And, of course, the green circle is the location of the tree, adjusted slightly for where it sits in relation to the expected top of the deck height.

Appologies for the lack of scale (this didn't make it out of visio), but for the most part the stumps are in a grid separated by 1.2 meters in each direction (so 1.2m bearer span and 1.2m joist span, the joists at 450mm intervals). I'm also planning on attaching a bearer to the posts that hold up the balcony area and staircase. I decided not to use the side of the house to attach bearers directly to because at the level I want to deck at they're just slats, as the house itself is up on stumps.

The decking will run top to bottom fairly simply, except for the bits around the tree (which should still be fairly straight forward) and the bit that intrudes into the stairwell. I'm planning here to actually use the 2nd lower step on the stair to attach the end of the joists to and to make up a funky triangular bit of decking in a frame of sorts to fit into this area (I can feel pain here already), in order to avoid pulling the stair out and rebuilding it, although I'm getting the feeling that the latter option might end up being easier in the long run.

In terms of material I'm currently thinking:

Stumps - concrete 100x100 (the type with the steel rod jutting out the top) cemented on top of packed dry concrete
Bearers - treated pine, 100x75 [width by height] (or perhaps 100x100?)
Joists - treated pine, 50x100 [at 450mm intervals]
Decking - 100x50, undecided on type of wood yet

As you can probably tell I'm something of a woodworking noob and haven't tackled anything more than bench building, so I'm not clear on the appropriate grade of treated pine to use and other such details. I'm a big fan of big sold things, and the impression that I'm under is that the dimensions I've listed are slightly over engineered (please correct me if I'm wrong!) but I'd prefer to err on the side of more sturdyness rather than trying to save a couple of hundred bucks on the construction.

Hopefully this makes some sense, and sorry for the long post. I'll try and grab a couple of photos of the desribed area if that would help clear up what I'm trying to do here.

Thanks in advance for any help

Cheers,
Neil.

[nmilne]

I've taken a couple of snaps of the area that is to be decked so that the plan view above makes more sense.







I've also worked out (duh) that I can actually mount stump/bearer sections on the house itself as there seem to be a fair number of decent stumps for the house itself that I can drill into for mounting (once I work out how I'm going to actually afix them given I can't get access to the other side in order to run a nut & bolt through). I'm working on a new plan view showing this and will post when done

[johnc]

Firstly you will need a building permit, and while you are enquiring about that ask about minimum sizes and spacings. The chances are whoever you speak to will be willing to give you the details to save hassles later on if the plan is not up to scratch.

Concrete posts are best so a tick there but the rest is slightly off beam. Posts to close, bearers I don't know but 75 x 50 should be fine for the joists and the 450mm spacings are about right. Don't go 50mm thick for decking, 20mm dressed is fine and not 100mm wide they will only cup in my opinion. Look at a deck laid in treated pine, the product is basic but the sizes are about right.

Have a look at a few decks if you can, observation will give a better idea of proportions. For bearer gaps look under the house and measure what's there, that will be suitable for the deck. I would keep the deck independant to the house and would not attempt to anchor your work to the house itself. It would be easiest to just put the bearer and stumps against the house rather than stuffing around drilling through in any case.

John

[Ivan in Oz]

Why do I always want to change things????????????

Have you considered Decking the whole area and [RE]using the Stairs
external.
Maybe down from where the present Patio is.

I like to have Options,
and Opinions

[aussieglen]

My strong suggestion is to obtain a copy of the Australian publication "Decks and Pergolas Construction Manual" by Allan Staines. It may be available at your library but is worth buying a copy from any reputable book store or from the internet - try this link - http://www.dymocks.com.au/ContentDyn...SBN=187521710X

I have already built 2 decks at home and am starting a third and have used this as my "bible " for the projects.
Hope this helps
Aussieglen

[nmilne]

Thanks for the replies guys ... I'm really thinking about using the house to mount some ledger plates for the joists to butt against and to act as the initial stumps on the top side of the plan. I know this will be a bit more stuffing around, but it helps space the stumps out when using 1.5m spacing and cuts out an additional 6 stump holes and associated fiddling around. In fitting the quasi-stump/ledger plates to the house stumps, is there something similar to a dynabolt that could be used? Or better just drilling a hole and then driving a pin through them both in an interference fit?

I've also decided to pull the stairs off, cut them short and re-use them to descend onto the decking. That was the right idea, thanks Ivan (btw, nice Mk.1 ). Think I'll go with 100x100 bearers and the 75x50 joists and 20mm decking as mentioned (thanks John), giving me a total rise of 195mm over the top of the stumps. This gives me a maximum deck height of about 750mm at the point where the ground drops off the most (in the lower right hand corner).

Here's an update of my thinking, with the drawing now adjusted properly for scale



I'll get on to the council and find out what hoops they need/want me to jump through tomorrow. My main concern at the moment are the 2 stump holes closest to the tree, as I'm sure I'll find a fat root through at least one of them...

[nmilne]

Just updated plans to include key and some basic dimensions ...