Hi All
I have reviewed the Trada Timber tables, in an effort to design my roof, and I have got a couple of questions.
The clear span of my roof is 6.8m, (so the run is 3.4m) and the pitch is 35 degrees.
That equates to a Rafter clear span of 4.15m.
The Trada table that I have got only goes up to rafters of 47 x 150, and for a Dead load of 0.5>0.75 the max clear span of those is 3.48.
At the moment, I am closing in on having 47 x 125 rafters, and then having 75 x 225 Purlins, 2.7m down from the ridge, spanning the 2.8 room without mid supports, that I will box in behind a non load bearing knee wall.
My question is – Are there tables available that will give me a rafter size that means I don’t need to use a Purlin, or am I then going outside of the boundaries of a ‘Simple’ roof and into the realms of complex calculations?
Cheers
Gary
I have reviewed the Trada Timber tables, in an effort to design my roof, and I have got a couple of questions.
The clear span of my roof is 6.8m, (so the run is 3.4m) and the pitch is 35 degrees.
That equates to a Rafter clear span of 4.15m.
The Trada table that I have got only goes up to rafters of 47 x 150, and for a Dead load of 0.5>0.75 the max clear span of those is 3.48.
At the moment, I am closing in on having 47 x 125 rafters, and then having 75 x 225 Purlins, 2.7m down from the ridge, spanning the 2.8 room without mid supports, that I will box in behind a non load bearing knee wall.
My question is – Are there tables available that will give me a rafter size that means I don’t need to use a Purlin, or am I then going outside of the boundaries of a ‘Simple’ roof and into the realms of complex calculations?
Cheers
Gary
