help with ridge board size

[lambo7719]

hi y'all. i'm new to thise site, but have a little query!
just on with a small kitchen extension for my folks, typical cavity wall, and pitched roof with gable end. It measures (roughly!) 3m x 5m, they wanted the roof kept open as high as poss to the ridge, i assumed this was fine due to the rafters being only 2m each in length, and advised myself to inform building control that we planned to beef up the ridgeboard to 9"x2", and the rafters to 5"X2", he came today and advised that the ridge board isnt substantial enough, and we must use rsj!!??, when i told him that was silly for such a little roof, he agreed we could use timberb if it was 12"x4", i reckon that would carry a couple of tractors worth of weight and think its a tad unnecessary, he said he'd consider changing his opinion with a structural engineers report, or even some data on the loads etc. Is it me or is that a bit extreme?

 

[freddiemercurystwin]

The lesser experienced inspectors will hide behind huge great beams as an over engineered solution unless you get calcs to prove it etc as you have been asked to provide. Sounds excessive to me too but then, I'm no engineer either!

 

[noseall]

Bite the bullet and use a 152mm x 89mm (u beam) with a 100 x 50m timber bolted to the top. This could be situated so that the rafters finish above it so it may mean a flat top to the apex as opposed to a point so that the beam can be boxed in.

Easy to fit, easy to lift, cheap to buy.

 

[Static]

I assume the ridge spans the 5m? Conc tiles on pitch or slates?
Basically if its the 5m span the inspector is probably right a small 9" timber isnt enough..

Mostly as said by others the inspectors will oversize cos its their liability etc..

 

[lambo7719]

Cheers all, Ive ordered the 12 x 4, its going up 2morrow! He said only rsj or (after some grumbling from me)12 x4 timber, its only cost 40 something quid anyway, so ive just gone with that, cheaper than s/engineers report, and easier to work with.
He's not a bad bloke as far as inspectors go, bit slack on timekeeping mind!