Hardwood decking sub frame design

31 Jul 2011
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United Kingdom
Hi, planning on a Balau hardwood deck, 4.2m x 6.8m, to be installed at ground level. I intend it to last as long as possible. So far as I can see the weak point will be the wooden posts that will hold the frame in position which will rot in time (I understand this will be many years, but they will not last as long as the Balau)

My solution is to install concrete support posts (designed for decking) that will support the sub frame rather than timber. See the item in link below
So far so good. I've installed a few decks before but using these posts presents a problem in levelling.

Normally I would install the posts, make the sub frame then position it next to the posts. Adjust the height to the post, bolt it together then cut the support post off at the correct height.

Using these concrete posts, there is a notch where the wood should sit which bears the weight, then the frame is bolted in to secure it. This means you have to put the posts in at exactly the right height before building the frame on top of them, which leaves very little margin for error.

I'm confident I can get this right, but wondered if I'm missing an easier way to do this. I have 50 support posts to install so want to ensure I set about this the best way.

Any thoughts?
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I think the idea behind using the concrete support posts is very sound, but as you say levelling everything up might prove difficult.

Have you seen these Postsaver sleeves:
They slip over timber posts and you use a blow torch to shrink them to fit.
Then you concrete the post into the ground with about 6" of the sleeve above ground.

I've used them for a close board fence I've recently erected and they were really easy to fit (just don't concentrate the torch on any one area for any length of time or the sleeve will melt - I speak from experience!)

That way you could avoid the levelling issue by using timber posts and also minimise the chance of rot.

Just a thought... :)
Good luck

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