Kevste123 Posted November 10 Share Posted November 10 Hi everyone, I have a 1930s traditional cut rafter roof 7.7m gable to gable and about the same distance between wall plates. 3 sets of purlins cut on mid-span truss with 9x3 tie beam at floor level. Rafter angle 37 degrees. Truss looks to have been strengthened at some point in the past with timbers added to attempt a w type. Picture attached. So it's kind of a king post setup without the vertical post. No internal load bearing walls at 1st floor. Existing rafters and joists are 3x2s. I had SE out for site visit who suggested 2x new steels for new floor, keep the lowest purlin to build up to but get rid of the two others and the mid-span truss. Ashlar wall, new deeper rafters alongside existing and new steel ridge beam. Can anyone please explain why the ridge beam is necessary? I suggested new timber affixed to underside of existing rafters and collar ties but SE said the new timber wouldn't double the rafter strength. I'm trying to understand where the extra load will be. I would ask SE but I have already asked a load of questions and probably got my money's worth, I don't want to take the p..!! so hoping someone here can help 🙂 many thanks Link to comment Share on other sites More sharing options...
Kevste123 Posted November 10 Author Share Posted November 10 Forgot to mention I am doing a velux only, no dormers. Link to comment Share on other sites More sharing options...
joe90 Posted November 10 Share Posted November 10 I am not an SE but have done many loft conversions and I don’t see why a steel ridge beam was necessary, I have only used them when large dormers were installed. @Gus Potter will be along shortly (hopefully) who will know more. Link to comment Share on other sites More sharing options...
Kevste123 Posted November 11 Author Share Posted November 11 I probably should've mentioned the other gable wall not shown in the photo is brick and consists of some corbelled brickwork to support the chimney stack. The chimney breasts (gathered) were removed from 1st and ground floor, this was done by a previous owner. SE said if I removed chimney stack the corbelling could go also, otherwise another steel would need to go in at eaves level. Not sure if this contributes in any way for the recommendation for the ridge beam though. Photos attached, sorry not the best Link to comment Share on other sites More sharing options...
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