I hope so, don't want to be adding insulated plasterboard to the wall now as stairs are in. Stringers are only 29mm wide, so would loose this using 20/12.5 (32.5mm) insulated plasterboard. Can see the purpose if the door was at the bottom of stairs, as essentially loft would become part of the stairwell. Walls are all internal as mid-terrace house. Am getting more than 2m head clearance, even with the 95x95mm CLS timber beam holding up the two trusses above stairs, its only the area above landing which needs some attention as not getting full clearance from edge of nosing, may have a recessed light installed into it to create a feature.
My local BC said if the room beside the new loft is unheated (neighbours attic unheated) then it's to be thermally upgraded, but just down to the new quarter turn landing. We put the insulated PB on first and butted staircase against that. Bit of a nonsense but they were picky and I did it, if yours don't want it ,great Think we did ever 2nd or third riser through the stronger with thunderbolts, my staircase manufacturer said they were the best thing for the job, no plugs required either
I had the Bc officer out today, always get a different one. Quite happy with the work so far but has advised to use 32.5mm insulated plasterboard on the party wall where stairs are fitted. Said it's best to remove existing plaster to brickwork the apply the new stuff. Think I may have to shift the stairs over slightly as don't want to loose the stringer behind plaster , he said after the door goes in then stud work can be applied to get thick insulation like I have done on opposite wall. He hasn't come across the Telebeams before, but did look at the roof rafters saying they looked undersized checking span with tape measure, said if I didn't hear back then its ok. Not happy on this side as it was my own decision to double them up, TB only advised to used rafters un-doubled? The rest of the insulation for the roof space said I could use triso along with 50mm celotex leaving a 50mm air flow. Rafters need counter-battening then triso added before adding another couterbatten with foil backed plasterboard on top. Which Is something I was looking at doing anyway with superquilt.
Just had the call from BC and they are saying the rafters don't meet there tables Telebeam only did calculations for the beam and not rafters. Have been asking them about this a number of times without reply. Have sent an email to Telebem requesting for calculations for rafters and about BC querying them.
She only looked from the ladder. Today's BC officer seems more informative. He pushed on the rafters saying there is flex. A bit worrying now after all the work I have put in Hoping that they can provided the calculations for rafters, nothing was mentioned in the plans to double or strengthen rafters, but a member on here did mention the looked undersized hence me doubling up.
Earlier in the thread, i did raise suspicions that the rafters might be undersize, i thought you said that you'd spoken to the TB people ? If you google "timber span tables" you will get some idea of what size does what span. Bit shoddy checking though, by the 1st BC Inspector
I asked them when I had the initial survey done prior to buying the beams, and have asked them twice in further emails. surveyor said wouldn't need to increase rafter sizes, as maintaining headroom was one of the main factors as wouldn't go ahead if headroom wasn't much. Now that its almost complete adding thicker timbers would reduce the size quite a bit, BC guy was quite tall They provided a binded booklet with all the installation instructions and calculations for the beams, but does not show the calculation for the rafters. An A3 page showing current truss positions and spans etc. On another page new plans showing converted loft with all the timber span sizes, so they were aware that the roof rafters would be spanning at what length and I should have been made aware if they needed strengthening. Original rafters are 95x35mm and about 600c/c. Going to be very stressful and soul destroying If I need to redo my hard work, spent full days in there in mid-winter and getting tired now after all this work
Span tables are showing 47x125mm CLS C16 at max span of 2.52m for 30-45° pitch roof at 400c/c. The span I have is 2350mm, but rafters are closer to 600c/c.
Don't the tables show 600 centers ? Quite surprised that TB didn't include specs for rafters, after all they connect to the Beams etc to form the structure. If push came to shove and you had to run 125 x 47 alongside existing, you will only lose about 30mm ? which don't sound too bad. I know with loft conversions every mm counts but, you are where you are now, and you could then insulate more between the rafters than under. Would it be so bad ??
Just looked at span table and you will need 125x47 Be surprised if BC lets it go without either structural calcs from TB or somewhere else
That's the size I am getting, I am not confident in TB getting the calcs, but do feel they are fully accountable for the error as they provided the service, and cost about £6000. This could have been a contractor carrying out the work as described in their Site Copy booklet. It going to be a lot of work and time as well as material cost to redo the work. The purlin above the stair will need to be dropped to allow allow for new rafter sizes as well as the other two for for the eaves storage. So basically I am redoing most of my work
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