over engneered or not?

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Hi Guys

just looking for advice on if i am over engineering the deck i am planning

joists are 400mm centers, you can see the number of posts in the pictures.

am i adding too many noggins here? i count 53 in total

deck finished size is 4m x 3m

design attached
 

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Unfortunately its over engineered but wrongly engineered.

Noggins are purely to stop the joists twisting they are not there to support other joists, they will help to a small degree but you need posts on every joist or on a cross member spanning under the joists. Noggins must cross the whole thing, having some joists with no noggins between defeats the purpose.

You have too many posts and too many noggins.

Aim for a post every 1.5m if using 6x2 joists or every 1.2m if using 4x2.

So forget the house side as its bolted to the wall for support. Run a line of posts along 1.5m from the house, one for each joist and then put 4 posts at 1m intervals along the 4m end joist.

Then one or two runs of noggins from one side right to the other.
 
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Unfortunately its over engineered but wrongly engineered.

Noggins are purely to stop the joists twisting they are not there to support other joists, they will help to a small degree but you need posts on every joist or on a cross member spanning under the joists. Noggins must cross the whole thing, having some joists with no noggins between defeats the purpose.

You have too many posts and too many noggins.

Aim for a post every 1.5m if using 6x2 joists or every 1.2m if using 4x2.

So forget the house side as its bolted to the wall for support. Run a line of posts along 1.5m from the house, one for each joist and then put 4 posts at 1m intervals along the 4m end joist.

Then one or two runs of noggins from one side right to the other.

how does this look mate? thanks for the help
 

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or this (replaced posts with a 2x8 brace on each side of the middle posts
 
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Yes that's better. No real need for the double joists at the ends though in my opinion.

If you have enough height clearance from the ground you could use a 6x2 joist perpendicular to and underneath the main joists. This could be bolted to 4 posts along the centre- line and remove the need for a post on every joist.

I think that's what you mean by a 8x2 brace? Same principle applies, 6x2'' support it every 1.5, 4x2 support it every 1.2m. An 8x2 is a bit over the top and will push you up off the ground even more.
 
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Yes that's better. No real need for the double joists at the ends though in my opinion.

If you have enough height clearance from the ground you could use a 6x2 joist perpendicular to and underneath the main joists. This could be bolted to 4 posts along the centre- line and remove the need for a post on every joist.

I think that's what you mean by a 8x2 brace? Same principle applies, 6x2'' support it every 1.5, 4x2 support it every 1.2m. An 8x2 is a bit over the top and will push you up off the ground even more.

this is what i have done based on your opinion, to be honest i dont mind raising it by 50mm to accomodate the 2x8.

it looks good mate, nice and even and not only do i not need to dig as many post holes it looks more evenly spaced.

Thanks very much for your advice, any chance i could fire a couple more questions your way?

Martyn
 

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Yea looks good. Ask away.
great thanks,

so do you think these fixings will suffice?

each beam will have joist hangers with 50mm galv ring shank nails fitted to them too.

Noggins will be nail gunned with 90mm galv ring shank nails
 

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