On 14 Dec, 13:42, "Dave Plowman (News)" wrote:
In article
,
sm_jamieson wrote:

Trying to think outside the box.
I have plenty of headroom in the loft. What sized timber I beam would
I need to use instead of the typical RSJ to support the ridge ? Loft
size 5.5m x 7.5m, normal cut roof with purlins at 1/3 and 2/3 heights,
V onto spine wall at purlin mid point, clay tiles etc.

It's more usual to install steel purlins - that's where the load is.

--
*Toilet stolen from police station. Cops have nothing to go on.

Dave Plowman London SW
To e-mail, change noise into sound.

Purlins need to be minimized (stairs running up parallel to the roof
slope), thus a ridge beam would be required to take some of the load
(why not, it's in dead space !), and the purlins only need to stop the
rafter sag. Roof pitch is quite steep at 40 degrees.
In the main section hopefully dwarf wall at 1/3 height and a ridge
beam will be enough. Purlins at 2/3 height are the awkward ones.
Simon.