Hi, I'm looking at vaulting the ceiling in a bedroom as the roof height isn't high enough to use the loft space for a room or storage. I've had structural drawings drawn up, which suggested a 203x203x46 UC ridge beam be installed. My question relates to what Building Control might further stipulate: the current roof joists are 4x2 - will they suggest adding 6x2? also what insulation and gaps will they stipulate, 50mm or 100mm. My concerns are increased cost and also just not creating much additional height once completed with new joists and deeper insulation/gaps etc, making it expensive and underwhelming once finished.
Are you a tradesperson and able to answer this question?
Unfortunately regional building control all have different opinions of what they want. Best advice is ask your structural engineer or the building control office for your own borough.
Hello, As the previous answer states a lot of BCO's have different opinions.
Inserting a steel will need adequate upgrades to allow suitable bearing points etc. Perhaps gable to gable with a suitable padstone?
In terms of timber depths (without knowing the span etc) 150mm would be the minimum required on a vaulted ceiling to allow sufficient airflow of 50mm with 100mm Kingspan fitted between the rafters then an additional 50mm Kingspan backed plasterboard fitted to the underside to finish giving you 150mm of insulation with 50mm of clear air flow, Additionally you would need some high level ventilation and low level ventilation fitted externally. (the above is based on underfelt being used currently on the roof, if you have a more modern breather membrane instead forget about the ventilation externally and reduce the airflow to 25mm if you want. if the current rafters and ceiling timbers are 4x2 they must be trusses or have some sort of collar tie, kingpost and possibly purlins involved?
My overall advice would be to get a SE out to do the correct calcs then source a good builder who knows what they are doing to provide a quote, this could be a lot larger of a job than you have realised.
Thanks.
