1st time decking post layout

Calzor Suzay · Post by **Calzor Suzay** » Mon Jul 06, 2020 9:18 pm

I'm going to building a decking for the 1st time.
Going to be using C24 47mm x 100mm joists attached to 100mm x 100mm posts via m12 coach bolts.
Will be using 400mm centre gaps between joists, 34mm x 145mm boards on the joists.
It'll sit no more than 100-200mm off the ground.

I plan to run the posts about 1200mm apart as it fits in with the size etc but not I'm not sure if you run the posts:-
a) 1200mm apart down every 400mm centres so every joist is attached to a post
b) 1200mm in each direction so across every 3rd joist.

For a deck 2.4m square (not what I have just an example)
Option a) would be 21 posts
Option b) would be 9 posts

Option a just sounds like over kill but I do like to over engineer things

ayjay · Post by **ayjay** » Mon Jul 06, 2020 10:08 pm

A 47 X 100 joist will safely span 1.92m - so they will all need supporting at each end and at every 1.92 m (or less) in between, and don't forget a row of solid noggins at every 2.4m of the joist length.