Timber Guide Dimensioning Framework Roof Truss

[Kortling]

If I use the wood guide to dimension a truss roof, the following info appears:

Roof joists with a light outer roof 0.4 KN/m2.

What does this mean in practice, is it dimensioned for a metal roof with accompanying insulation, with battens for the interior ceiling and plasterboard as the interior ceiling?




What is meant by the height outside the load-bearing wall 350mm?

What is meant by the height at the support leg 1200mm? Should the support leg be placed where the truss is 1200mm above the bottom chord?

What is meant by the height to the collar beam?

 

[larsbj]

Sheet metal or felt is considered a light roofing material.

It seems there is a raised wall structure of 350mm.

1200 mm between the bottom frame and the top frame.

 

[Kortling]

Anyone know if the load 0.4 KN/m corresponds to a light metal roof with insulation, battens, and an interior ceiling of gypsum or boards?

 

[KnockOnWood]

I recommend Nässjö Takstolsfabrik, http://www.takstolsfabriken.se/
They perform all calculations and deliver at the agreed price.
Definitely worth the price in my opinion.

http://www.takstolsfabriken.se/offertforfragan/ramverk/

 

[Kortling]

It concerns existing rafters.

 

[Oldboy]

Does anyone know if the load 0.4 KN / corresponds to a light metal roof with insulation, battens, and an inner ceiling of plaster or boards?

It should. You can't really build an insulated roof much lighter than that.

Compare kg/m2 between concrete tiles and metal roofing. That's probably the rough dividing line between light and heavy roofs.

 

[Kortling]

I calculate that 0.4 KN corresponds to 40 kg/m2.

With sheet metal 8 kg/m2
Råspont 9 kg/m2
Gypsum 9 kg/m2
This gives approximately 14 kg/m2 left for felt and insulation, which should be fully sufficient.