Loft Conversion Timber Ridge Beam

[LaurenceH]

Good Evening,

I am hoping there is somebody on here that can help me, having failed with phone calls to the 12 structural engineers that are on holiday, in a meeting, wanting to charge a fortune, etc.....

I have been a joiner for 10 years and have decided to bite the bullet and build a double dormer loft conversion for my parents semi-detached bungalow. I was perfectly happy and confident with all aspects of the project, until our draftsman said "I have just put 'structural ridge beam' on the drawings, if building control ask for it you will have to provide the calcs for the timber used." - Yes, Great, Thanks for that!!!

The problem is this. I was going to massively over spec the timber and grading to make sure that it can't cause problems for us when an inspection is carried out. But now I am doubting this and can't get an engineer to do the calcs for me, not for less than £300 anyway!

I have uploaded the drawings and if anybody could help me out with over sizing this timber I would be extremely grateful?

Thank You in advance and this is a great forum!

 

[LaurenceH]

Just some extra info also:

The span in 6.5m and I was thinking a 75x300 graded c16 would be a good size.

Please tell me if i'm way off.

 

[freddiemercurystwin]

Try Simon at http://www.nichollsbasker.co.uk/ he's never done a site visit for me (but not sure if distance would be an issue, might need to say pay half up front maybe?) but I always provide him with everything another SE might gain from a site visit and has done little jobs like this for me as little fill in jobs in between his proper jobs when he's got a spare hour or so. So maybe worth a shout.

 

[LaurenceH]

I have sent him an email this morning. Thank You

 

[freddiemercurystwin]

Ring him up.

 

[jeds]

Just some extra info also:

The span in 6.5m and I was thinking a 75x300 graded c16 would be a good size.

Please tell me if i'm way off.

Way off. I've spec'd timber ridges for half that span but deflection increases with the cube of the span length so doubling the span increases deflection by a factor of 8. In short you will need a steel beam - properly calculated.

 

[^woody^]

Why does this need a ridge beam, when the roof is braced by the ceiling joists, and rafters supported by the intermediate stud wall?

 

[ibby]

Timber beam wont fit, I tried this with my loft conversion.

It just doesn't happen! The timber beam will become too big to handle.

 

[LaurenceH]

Hi ibby,

Thanks for the reply. What did you have to do instead. Steel or Structual studwork?

Thanks

 

[ibby]

If you want my advice go for a steel, In order wise when I had it installed..

- It was two sections, had it winched around the outside of the house onto the scaffolding.
- Brick work was notched through and the RSJ padstones installed. (at this point the tiles were stripped off the roof and only felt was left. The roof was tied down to the new floor offering it support at mid sections.
- They inserted the beam through and built a scaffolding platform to support it then used a jack to lift it into place.

305 x 146x 54 or was it 64. It has been a while. Mine was a 7.5 meter span, it was spliced in two locations. The cost was around 700£ delivered with the splice and bolts.