Unusual Decking Question...

[skilly]

I am about to start building my first deck and have was wondering how much load can they carry?

I intend to build a 2 tier construction (one on the ground 12'x16' with a 4"x2" frame throughout and the other 12'x15' approx 24" off the ground with a 6"x2" frame and 4"x2" joists). I will be concreting the 4"x4" posts for the upper deck into the ground (clay soil) to a depth of 2'. BUT...

As I have a couple of mates who are rather rotund (over 24st) my wife reckons that I should be altering the spacing for the posts and rather than the normal 1200mm centres I should put them closer together to make sure that it doesn't sag if we are all on it.

So I was thinking of doing them at 900mm centres (as that will fit evenly with the overall sizes of the deck)....


1) Is it necessary to change the spacing of the posts?
2) If so then does 900mm seem reasonable? If I carry this on under the entire frame then it means I have 30 posts supporting the deck.....Have I over engineered the structure?
3) Any other advice would be very much appreciated.


OF course I could always restrict the big folk to the lower tier!!!


Many thanks.

 

[Deluks]

OF course I could always restrict the big folk to the lower tier!!!

Put the barby on the bottom section, and the salad bar on the top section. Problem solved!

 

[WabbitPoo]

I wonder why you are using 4x2 joists at all? Use 6" and the whole thing will be better.

My decks have had big parties on them, 20 people without problems. Unless all your friends are overweight slobs then don't worry too much. Put the supports closer if it'll give you confidence.

 

[skilly]

Cheers guys..

One other question....am I better nailing or screwing the joists to the frame?

 

[WabbitPoo]

Screwing.

 

[skilly]

Back again!!!


Went to get prices for the timber and completely baffled myself....it ain't difficult.


What timber should I be ordering??

Treated --- yeah.
Strength graded???
Regularised???


What is the differences between these types and what should I be getting?


Many thanks....AGAIN!

 

[Deluks]

Treated C16 will do. If regularised is the same price then have that as well. The main thing is that it's treated.