3/4 ply as a deck?

Is this advisable? Deck will be entirely protected from the elements. We were given some nice plywood, so wondering if this can be used ok... can't find many references on the 'net, other than roof decks and all the weatherproofing they need...

Cheers
Andrea
Oxford

we used painted 19mm as a side deck up north. and 17mm on the front 120SqM deck that was to get 7mm fibrebord capping that we never got around to installing. Works quite well, everything got copious amounts of silicone seal upon laying and kept the underneath storage nice and dry.

I gather it is treated and if so can`t see a problem tkf

I also think it depends on the under support as far as piers etc go. I recently looked at a house for M & D and the deck was plywood type structure, but as springy as E's trampoline.

if we had bought the place, I would have ripped the whole lot out, extended the gable end of the main bedroom and re-done the deck with composite strip flooring.

Our decking on this house (the rebuild) and the village house have both shrunk hugely since installation and SOH spent lots of effort to ensure the angles etc were cut correctly. he need not have wasted his time in hindsight.

Absolutely unacceptable.

Great thanks! It's exterior grade, and treated, so should be fine.

Cheers
Andrea
Oxford

I think the recommended ctrs for support joists of regular decking is 16"... do you think closer together would be necessary for plywood?

Thanks for that, swaggie.

Andrea
Oxford

Andrea I know our verandah was over engineered for council approval and this is because if people have an outdoor party and they are all on the deck at once, its under more pressure to collapse.

Our inspector was in awe of what the engineers designed for the job here and that is just the way engineers here design things, because at the end of the day if the deck complies with its building regs then collapses, the approving authorities and designers are next in line for suing....

all I can suggest is to check with your local authority as to what they want from your reno.

Andrea;296209 wrote: I think the recommended ctrs for support joists of regular decking is 16"... do you think closer together would be necessary for plywood?

Thanks for that, swaggie.

Andrea
Oxford

Our side deck was 4x2 bearers at 600mm spacing, with 3x2 nogs every 400mm, over 6x2 joists on piles, that was under the side decking where everyone walks to and fro and in the sliding doors there. The main deck sticking out over the bank was 4.8M or 3.6M (dependant on which span it was over) 8x2 bearers/joists at 600mm with 4x2 nogs at 600mm, over dual 6x2s making 6x4 spanning the piles. Where the side ply deck on one side and the side tread timber deck on the other met the ply deck out front, the nogs were 8x2s. All dimensions divisible by 2400 and 1200

That main deck job took me all summer one year working weekends and holidays home from uni, pretty much by myself. The handrail went up in one day of all 5 of us working. (Mum, Elder sister, Me, younger brother and younger sister)

Here's three pics, one of the deck in it's bare essentials, the next competed from the lawn, and a final one down the hill at the distant deck.

Nice deck, kiwi! Well done! The one we want to do from the ply isn't anywhere near as ambitious or large or that high off the ground (will only be a step up, actually), and not even in a high-traffic area. Just looking forward to sprucing this place up a bit now that we've most of the farm infrastructure done after 5 years here, chipping away as time and funds allow.

Thanks everyone for the advice!

Andrea
Oxford

Just talked to neighbour who has one and he said if it's uncovered he cut small saw cuts in it to get rid of water and stop it getting slippery

Thanks, sod - this one will be completely covered, with an overhang that won't allow much rain on it, plus there's a really dense shelter belt behind (southerly side), so that side of the house is really protected when the southerlies are up.

Cheers!
Andrea
Oxford

It's easier to just make a 1cm drop per 2.4M length to allow water runoff, and paint with a rubberised high wear ships deck paint from Burnsco or other ships chandlers. Cutting the ply can weaken it by exposing the inner laminatee. other wise a THICK coat of standard house exterior paint topped by shaking fine sieved beach sand over the wet paint will give good grip for a while, and it easy to replace as it wears under your feet.

P.S. have the under deck timber all gauged to equal thickness, roughsawn timber can be uneven, so you need to wath the levels a lot more, if all the timber is identical, you finish with a much better job and no water pooling or uneven runoff...

Thanks for that. None of the sheets are going to be cut, and it's going to be waterproofed anyway, just to be on the safe side. Warped plywood is no fun. The timber's going to come from Gold Pine, and DH is planning to install it on a slight angle to encourage runoff if necessary (you never can tell with Mother Nature!). DH was wondering aloud about using a marine grade paint, so I think we will go to that extra length.

Cheers
Andrea

Nice job, Kiwi

There are specific paints designed for the high wear floor situation and a little sand between the last 2 coats is required if there is any likelihood of moisture underfoot especially if this is a main access to a house.
For these paints to last well make sure the surface prep is good.

19mm ply should span 400mm for light use flooring, (not heavy loads eg cars, groups of dancing people) and may span further depending on the direction of the face grain and the stress grade of the ply. For further info look at page 26-27 of this link:
www.ecoply.co.nz/UserFiles/Ecoply/File/E...l_Mar_2008_final.pdf