decking 4x2 joists

[danlightbulb]

Hi,

Is a 4x2 ledger board and support framework good enough for a raised deck? Am hoping to have an unsupported joist span of 1.8m max.

Cheers
Dan

 

[ColJack]

I suppose that depends..

if you put 2 x 4's straight onto the slabs at 100mm centers then I expect that they'd be great at supporting the deck..
if you're suspending the deck 2 foot in the air with only 1 post each corner and the 2 x 4's at 1000mm centers then I'd ecpect it to be a bit bouncy..

posts every 1m or so and 400mm centers then I recon it might be up to the job, but unless it's a huge deck then the price difference for 6x2's souldn't be that much surely?

please bear in mind that I'm a sparky by trade and only offering advice based on what I've read or watched on telly.. so the pro's will be along in a minute to condem what I've said no doubt..

 

[Thermo]

as col says, 6 x 2 much better. You can use 4 x 2 but youll need more supprts and you wont get away with a 1.8m span without supports

 

[ColJack]

yay.. I got one sort of right for a change..

 

[danlightbulb]

Hi all thanks for replies.

Yeah i was planning to put deck bearers at 400mm centres but the span of these would be 1.8 m from ledger board to post. I was going to put posts at around 1.8m apart too and could double up on the bearers at the post side.

The reason im asking is that a 6x2 ledger board would put the deck a little higher than id like at the post end, and im trying to avoid having to put an intermediate step down onto the grass.

Cost is an issue too as there will be around 100m of joists in total if i use 400mm centres and 2 rows of noggins.

Cheers

 

[Thermo]

if the height is an issue then you can use 4 x 2. It will be a false economy to think that 4 x 2 will be cheaper as you end up putting in more posts and more concrete. DOnt go further apart than 400mm on the centres, the deck will bounce.

Its like anything you build the key is in getting teh structure right, so its worth doing it properly first time and spending a little more on it

 

[WabbitPoo]

To see if the pros here are right (and they are) put a long length of 4x2 onto two bricks, then stand on the middle. You'll soon see how much deflection you'd get. Now try it with 6x2........

 

[danlightbulb]

Hi all, thanks for replies so far.

Im going to use 6x2 now.

The joist span tables here: http://www.diydoctor.org.uk/projects/load-bearing_walls.htm indicate that on 400mm centres a max joist span of 3.06m is allowed.

Have I interpreted this correctly and does the same also apply to the distance between posts at the front?

Also, are 100mm screws ok for the joists to ledger board, joists to front boards and front boards to posts?

And would someone be able to advise on what fixings to use for the ledger board to brick wall please.

Edit 15:40 - would really appreciate opinions on my main frame layout. See picture.

Untitled

• danlightbulb
• 28 Jun 2010
• 1

Many thanks
Dan