hanging joists off a king beam

[marsaday]

I have a spine wall dividing my house and on this sits a king beam holding up the centre of the roof. This sits onto a plinth which sits on top of the spine wall. is it ok to hang joists from this wall? View media item 692
View media item 693

 

[anobium]

Not really sure what you are proposing to do, and I am a bit confused with your terminology.
From the pics it looks like you have a king post roof truss, thats the big triangular section which is primarily there to support the roof ,ie purlins and rafters.
If you considering putting joists on the tie beam, that is the lower horizontal member of the triangle, then I would ask a qualified SE to do the calculations.
More pics and a sketch of your proposals would help.

 

[marsaday]

yes, that is what i plan to do. hang joists from the horizontal member sat on the spine wall. it is a big joist, i think a 9 x2.

i think i need to get a SE in to check all this out.