Planning a Pool Deck

[Clive McF]

Hi all. So while I wait for my bricks to turn up I have to draw up my pool decking plans and would appreciate your advice. It’s for a semi in-ground pool, deck approx 650mm high. Cantilever log retaining walls on 3 sides, brick wall on 4<SUP>th</SUP> side. To visualise, draw a rectangle with short sides top & bottom, long sides left and right. Put an oval in the middle for the pool. Rectangle is approx 11m by 6.5m, pool 8.5 by 3.5m, width of decking from pool to edges of rectangle about 1m. The brick wall is the bottom short side, other 3 sides are the log walls. Because I’d like to recycle some joists, I’d like to lay this out what I guess is the non-obvious way, ie with long bearers running top to bottom and short joists running left to right. First question: is this going to cause me more hassle than it’s worth?

If not, then here’s the rest of the plan. Bolt 140*45 F7 treated pine ledgers to retaining wall posts (175mm dia treated pine) at 1200mm crs. Ditto for brick wall. Footings at approx 1500mm crs, 400mm dia by 500mm deep concrete pads with stirrups for 90*90 F7 treated pine posts (soil class M). Bearers 150*50 F7 TP, notched into posts. Joists 100*50 hardwood (yeah, I know, nailing will be so much fun…) at 450crs. Are there any problems with this approach? Improvements? Advice?

Bonus questions: what’s the best way to join the bearers, since I’ll need to run several lengths end-to end to get the long runs? Oh and finally (Produces tin opener. Picks up can of worms) what’s the best (ie lowest maintenance) type of timber to use for exposed pool decking? Thanks in advance everyone. Clive

[mic-d]

I think the only problem with running the joists L2R is that the decking will be running with the long axis of the pool and the decking adjacent the pool may need to be cut with long thin tapers which could be a splinter hazard. Of course laying it the other way you may face the same problem across the ends of the pool. Only you'll be able to judge that by looking at the curves of the pool.
F7 150x50 bearer is adequate but I would probably go to 175x50.
Join bearers with a scarf joint at posts, one 12mm gal bolt in each.
Arguably the best deck timber for around pools is Yellow Cedar but its expensive. Does not splinter and finishing is optional. I have used yellow belau with success, Kwilla is also good.
Look at Spa-n-Deck as your deck treatment.

Cheers
Michael

[Clive McF]

Thanks Michael: I'll increase the bearer size as you suggest. Since the ends of the pool are semicircular I'm going to end up with tapered decking either way I guess. Sketching the layout along these lines (images attached) inevitably I end up with more questions. First, how do I join the 4 angled bearers to the adjacent bearers (over posts)? Second, because most of the joists are short, the proportion of each joist which is cantilevered can become quite substantial: is this a problem? All other comments and advice welcome, as always.

Cheers
Clive

[mic-d]

Gday Clive, I'd be using long gal batten screws to join the angled bearers over theposts, say 100mm and 3 of. If you can fit bots though, that would be preferable. Pryda make a bunch of different gal angles and gang nails that may also be useful. Have a look at the range and find the ones that fit your need. For instance, with your joists I'd probably use triple grips in addition/instead of skew nailing the joists. How much of the joists will be cantilevered?

Cheers
Michael

[Clive McF]

Hi Michael, I guess since the bearers would be 50mm wide I could just about get away with a couple (?) of 12mm bolts as in sketch A, with the bearers sitting on top of the post? Or would I be better off notching into the post and bolting into it (sketch B)?

Entirely agree about grips for the joists: not looking forward to nailing the hardwood. But I have plenty of them salvaged from a demolition and I can't bear to chuck 'em out for landfill...

Worst case scenario for the cantilevered joists is around the middle of the long edges of the pool - joist around 1275mm long spans 2 bearers at 750mm crs and extends about 350mm beyond the centre of one of the bearers. So the actual length cantilevered is pretty short, but of course is about 50% of the joist span...

Cheers

Clive

[mic-d]

Those 2 diagrams make me shudder a bit. May be misleading but I wouldn't like to have fasteners so close to the end. think about having some steel angles made up that will sit across the bearer joints and be bolted in further back from the ends. get them hotdip gal too, pool water is corrosive.

Cheers
Michael
BTW, Here's another idea for bearer/joist/deck layout that would avoid long tapers next to the pool. Think of bringing bearers in from the corners at around 45º (say the 1:30, 4:30, 7:30 and 10:30 clock positions on the circular ends). Then lay the joists out so that the decking at the top and bottom runs up/down, and the decking at the left and right runs left right. Rather than butting the decking together where it changes direction (which will look ugly because the boards will not be in register) run a spline (20mm wide piece of edge ripped off decking) along those joints - looks much better. You'll have to rework the bearer layout a bit, but I'm not going to tell you everything

[Clive McF]

Ah, there'd be a logic and beauty to that layout, wouldn't there? But it brings me back to my original problem of the non-obvious layout in order to recycle my joists. So will probably go with your fine suggestion of getting some angles made up, and flicking through the Pryda catalogue. Then all I'm left to worry about is the cantilevering..

Cheers

Clive