RSJ

[Cy01]

Hi,

I am looking at having a loft conversion done.
It will mean the construction of a dormer that spans the length of the house.
this is approx 11 meters.
I know i need some steels - not yet commissioned some plans - doing so now - but i have seen a steel that I think will be suitable at a fraction of the price I would have to pay. I am looking for a bit of advice to see if anyone could let me know if a 254 x 146 would be suitable to support new floor and dormer?
comments appreciated

 

[freddiemercurystwin]

No where near enough info to comment. Appoint your SE. Whats the width of your house? A steel to span the 11m would be about twice the size of the one you've seen. Two or three steels spanning width ways will likely be more practicable.

The rule of thumb for steel sizes is the depth = 1/20th span.

 

[Cy01]

Thanks for taking the time to reply.
The width is 5meters - length is 11 meters.
I am thinking that the beam would work as either the beam that acts as the wall plate or the ridge beam? The ridge beam will simply act as the point to support existing pitched roof and the new dormer roof. Does that make any sense?

 

[freddiemercurystwin]

Aye makes sense, as mentioned though

The rule of thumb for steel sizes is the depth = 1/20th span.

so your 254 will be undersized as a ridge and may or may not be OK for use across the width. only an SE or other suitably qualified person can say so. Buy at your own risk.