The height between the felt roof and the decking?

[Mariana Back]

Hi,
We have laid new roofing paper on the garage roof (roof with railing = terrace)
Now I want to lay wooden decking on top. How high should the joists be?
What width of floorboards is most suitable?
Thank you very much in advance for your response

 

[Rickard.]

How high should the joist be?

It must be high enough so there is no risk of the decking screw going through + a little safety margin.

What width of floorboards is most suitable?

It doesn't really matter, so choose the one you think looks best.

 

[Pasjostrom]

The height of the beam also depends on how high you want the decking to sit.
I would recommend decking that is 28x120, it is the most common dimension and does not flex if you space the beams cc60cm.