Composite decking joists

AdrianC

Doozergirl said:

Don't forget your planning permission if you're above 300mm high...

Ah, yes. Good point. I did, of course, mean just under 300.

I wonder how that's calculated, on wobbly-but-basically-flat ground?

Jeepers_Creepers

Hopefully from the highest nob on the nobby ground. 

AdrianC

A long-overdue update - it got built, finishing at the end of last month, with a semi-trade friend who's done other decking in the past.

We ended up using 80x80 posts from Kedel
https://www.kedel.co.uk/mixed-plastic-lumber/recycled-mixed-plastic-square-post-with-pyramid-head-80mm-x-80mm.html

with joists and boards from Neotimber
https://neotimber.com/decking/shop/large-plastic-joist/
https://neotimber.com/decking/composite-decking/essential/

It's bloody weird stuff to work with - it cuts like timber, but it produces swarf like machining metal. It's bendy as anything - but rock-solid once the frame's all built up. We used c.400mm joist spacing, much smaller than you would with timber.

You cannot nail it - not without pilot holes.
Once screws (all stainless) are in, they are IN. They are never coming out again - we think that it melts slightly around the screw and self-heals. Try and remove them, and the heads will round, then they shear.

The ground turned into a saga in itself... We used a petrol auger to drill holes, then postcrete the posts in - only to find that the ground is basically all made-up from rubble and 1970s catering rubbish and buried wriggly tin and asbestos-cement sheet with a nest of baby shrews in between... Then we found a large, disused soakaway - 5m3 of MOT went into that alone, with a petrol whackerplate to compact it... Then I fell through the joists while walking on them, and narrowly avoided a badly broken leg... At one point, we were seriously referring to it as "the cursed decking". But it's done, and it looks fab.

Doozergirl

Photos or it didn't happen! 😉

I really do think you're doing it properly when your subframe is composite too.  Arguably, it's the most important bit! 

AdrianC

Doozergirl said:

Photos or it didn't happen! 😉

The surroundings are a little less than optimal currently. Getting some hacking-back done and rubbish cleared is a winter job.


^ Arty lifestyle shot... The ground drops sharply away.


^ More prosaic shot...

It's finished up as 5.4m (1.5 boards) wide, 3m (joist) deep. Height off the ground varies widely - you're looking at the tallest, just  under 300mm, honest...

It's on the back of an outbuilding which is 'erselfs studio - built in the 70s as a kitchen for a then-occupant's outside catering business, and a pottery for our predecessors. Next big job is to replace the tin shed. The structure is, well, some fast-grown sprucey saplings that have mostly rotted away at ground level. It's a big building - 11m x 6m, ignoring the slight dogleg round the back of the studio, with a cap on roof height because of the eaves of the studio and because of a high-level window in that end wall. I want to go steel-frame with it, so just waiting for steel prices to return to sanity.

Doozergirl

Looking good!  

I'm waiting for the price of everything to drop! 

phoebe1989seb

Doozergirl said:

Looking good!  

I'm waiting for the price of everything to drop! 

Me too 🙄

That's looking great, Adrian.... thanks for the update 😃

Was following with interest as we're going to be adding a composite decking area to our garden here in Wales (probably next year now 😎) and although we've decided on the boards themselves (Millboard embered weathered oak), we are still wincing at the cost of the composite joists etc, but think we'll have to bite the bullet.....

Bendy_House

Lovely stuff, Adrian, and thanks for the update.

Haven't put it down yet, but our planned-and-bought 6m x 3m decking - 295mm-wide composite boards, 75mm aluminium joists and all clips and fixings (except joist pedestals) came to £1900, of which £300 was delivery. This is Dura Deck Eco 295 stuff.

I think that's pretty good if it lasts 'forever'!

AdrianC

I haven't added up what it cost, and I don't want to.

It's the silly stuff, like a 100 box of 6.3 x 125 stainless screws at £60, four 200 boxes of 5 x 100 at £40 each... And then you tie knots in the sodding things.

travis-powers

Looks outstanding!
really good job done well!
Any plans for the tin shed?