Thread: deck bearer and joists

Originally Posted by gilbo

I want to build a deck with dimensions of about 5 metres by 9.5 metres. The deck is low to the ground (about 300mm), so I would like to minimise bearer thickness and hang joists between beaeres using joist hangers. The base framework would be F7 treated pine and the decking would be hardwood. Can anyone help me with the spacing of peers bearers and joists, and the size of bearers and joists I might need?

Bearers : 190 x 35 F7 CCA spanning in the long direction, 3 double spans per 9.5 m run, stumps/piers at 1600 max crs.

Joists: 190x35 F7 CCA - 450crs spanning 2500mm , joist hanger fix to bearers.

Dont forget to fix decking with spiral shank nails

Give this a go: http://www.woodworkforums.ubeaut.com...ad.php?t=22975

For what you want to do, you might also look into Duragal. They've got a flooring system that would let you run bearers and joists at the same level. You can get it from Bega. If you're up there, go to OneSteel out near the Cheese Factory and pick up a brochure. You can fix hardwood decking to it. Might be an alternative because 300mm is pretty close to the ground and you're really meant to be at least 400mm to the bottom of the bearer unless it's a sloping site. You need to be a couple of k's from the beach to use it though.

Originally Posted by silentC

Give this a go: http://www.woodworkforums.ubeaut.com...ad.php?t=22975

For what you want to do, you might also look into Duragal. They've got a flooring system that would let you run bearers and joists at the same level. You can get it from Bega. If you're up there, go to OneSteel out near the Cheese Factory and pick up a brochure. You can fix hardwood decking to it. Might be an alternative because 300mm is pretty close to the ground and you're really meant to be at least 400mm to the bottom of the bearer unless it's a sloping site. You need to be a couple of k's from the beach to use it though.

Not sure if 400mm subfloor clearance applies to decks. At any rate it sounds like gilbo cant get 400mm anyway.

Be careful with Duragal in fully exposed near coastal environments. the coating is very thin and may not stand the test of time. Duragal will also be very expensive compared to timber. I think CCA hardwood would be a betterm compromise, you could get 125x50mm joists to span off 125x75mm bearers.

My 2c worth.

Forgot to add. If you do build your deck that close to the ground, make sure the area is well drained and ventilated, consider slightly larger gaps between your decking. There is potential there for the decking to cup if the conditions under the deck are too moist. It could even be worth priming the underside face of the decking if in doubt.

I know it applies to verandahs, can't say on decks but I'm not sure why it would be different.

I'm using Duragal for the verandah sub floor in our new place at Pambula because of fire restrictions. The house next door has a full duragal floor. As long as you install it properly (fully flashed and water proofed) it's supposed to be OK. We're about 3km from the beach and according to OneSteel, we're OK with it. Anyway it will be painted.

Price-wise, yes it will be a fair bit more expensive. If you can get what you want with timber, then go for it. I just put it up as an alternative.

Originally Posted by silentC

Price-wise, yes it will be a fair bit more expensive. If you can get what you want with timber, then go for it. I just put it up as an alternative.

Fair call.

Just another thing. Unroofed low level decks are exempt from building approvals in QLD. Dont know about Pambula. You should check the subfloor clearance req's out with a building certifier or council before you build.