What timbers should i use to make a 3m x 3m span

[KarlBezant]

I have a new build with a detatched garage that I wanted to board up the roof space to create more storage. Alot of pages mentioned that the roof trusses are not designed for extra weight so I started looking in to other solutions.

The main idea is to create 2, 3m x 3m spans supported on vertical timbers from the ground to just under the roof trusses. I would then make (As someone else described) goalposts across the top of them, and then joists between these which would be taller than the existing trusses allowing me to attach OSB to them without putting any extra weight on the roof trusses at all.

I am trying to figure out what dimension timbers to use to achieve this and if this is safe to do. Any help would be greatly appreciated.

The pictures (sorry for the crude doodles) might help to visualize. My idea is to do 2 separate sections, and I have only drawn in 2 of the joists joining the "Goalposts" which would be along the whole width.

Kind regards.

Karl

 

[Wayners]

9x2inch I have

 

[JohnD]

is that at 40cm centres?

 

[Dereekoo]

is that at 40cm centres?

And is that for goalposts size as well, and is it c16 or c24 and what design floor loading did you use or was it finger in the air design

 

[freddiemercurystwin]

What are you storing up there? Unless it's really heavy you don't need anything additional.

 

[cdbe]

What are you storing up there?

Looks like "everything"

Maybe a few 8x2's across the 3m span on hangers or ledgers if it's being boarded and fairly heavily loaded?

Can't see the point of the vertical posts next to perfectly good walls.

 

[Wayners]

IMO.

2 x 6 inch would be fine every 600mm off joist hangers and stick a floor down.
Be a good floor.

2 x 4 inch would probably be fine for just storage every 600mm.
Many houses have that as standard flooring.

Building regs I had 9 x 2 and well over engineered. Spaced every 600mm.

 

[Dereekoo]

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