Originally Posted by Peter M
Are the rafters actually the bottom chords of your roof trusses ? Can you show us a shot of the attic ?
I only ask because I'm a structural engineer and I think there must be something else going on above the ceiling, or the rafters simply wouldn't hold up with that gang-nail joint.
Yes, that's correct. It's a no on a picture, unless I can find and old one, I won't have access to if for quite a while and I wouldn't want to publish the mess anyway.
But I can describe them;
first of all, they stick out say half a meter, 2 feet on the other side of the walls. There is a single straight riser part | in the center, so it's not a /\/\/\ construction. The other ceiling is full tongue&groove board covered with concrete tiles on. I don't know the slope by memory, but I can almost stand straight in the center inbetween the trusses and I'm 169cm ( 5'8").
Hope that makes sense to you, as a non-native in English, the building construction glossary is a weak side for me, being a computer engineer...
BUT; does that mean I will need to to go bigger on the rafters for the room-within-room build? Even if they'll just be taking the load for OSB+dual drywall and some insulation - not an attic full of junk as well. I will be needing to make a joint too, I can't get full length ones inside. The span will be about 450cm (15 feet). I'll be halving the spacing of them, so one every 600mm, so there will be more of them to distribute the load on. Will 165x45 not do the trick, what will I be needing - 180/200/220?Edited by Nightlord - 5/12/13 at 10:56pm