Flat Roof - Firrings, What Size?

[rvp]

Alrite guys.

Quick question.

I'm in the process of repairing my Garage flat roof due to leakage caused by water pooling and was wondering what size firrings to use after looking into the best ways to create a run off.

Garage is around 5.3 mtrs long x 2.5 mtrs wide.

What size Firrings would be best? local timber merchant will cut to size hence the question.

Cheers all.

 

[Porque223]

Using the engineering toolbox website and the modulus of elasticity for your wood an answer may be forthcoming but the distributed load and the recommended deflection need to be known.
Do you get snow where you are?
Will you be walking on the roof (which is a concentrated impact load)?

 

[rvp]

Using the engineering toolbox website and the modulus of elasticity for your wood an answer may be forthcoming but the distributed load and the recommended deflection need to be known.
Do you get snow where you are?
Will you be walking on the roof (which is a concentrated impact load)?

Hi Porque,

Wow I never thought it was that complex! I am just looking to get a run off from existing joists because I have found out the roof is pooling water due to a slight sag of mentioned joists.

Snow, just the usual like anywhere else in the uk really and a I wouldnt be walking on it.

I would just like to cure the pooling problem that is all.

Cheers.

 

[rvp]

Anyone?

 

[pinenot]

3"x2" cut to 2 7/8" > 1/2" over the length, 1/2" deletes sharp edge (easier to handle/nail etc.)...pinenot