Building regs help
Discussion
Discuss with your Building Control Officer - some are more anal than others and they's taken the old span/joist sizing tables out of the Approved Document, so technically he could demand structural engineer's calcs, but from an old copy of the tables in Approved Document A, 200x50's would be a bit light: even at 400 centres, they'd only give you a maximum span of 4.79 metres.
From the tables, 225x63 at 450 centres would be your minimum (suitable for a span of up to 5.57 metres and dead load of 0.5kN/m2).
I'm sure a Structural Engineer will be along shortly to give more accurate advice, though.
From the tables, 225x63 at 450 centres would be your minimum (suitable for a span of up to 5.57 metres and dead load of 0.5kN/m2).
I'm sure a Structural Engineer will be along shortly to give more accurate advice, though.
Sam_68 said:
Discuss with your Building Control Officer - some are more anal than others
I'll go along with that. Last year i had no option but to put a flat roof on an extension, iirc just slighty longer than the 5.5 you after, and she said 220x50 was fine. So yeah, talk with your BCO.They used to be in Approved Document A to the Building Regulations, but they've taken them out these days.
Having just looked, the amendment notes in the current Approved Document says 'guidance on sizing of traditional timber floors and roofs has been removed as the timber tables are now published by TRADA'.
TRADA seem to charge for their information, but try here
Having just looked, the amendment notes in the current Approved Document says 'guidance on sizing of traditional timber floors and roofs has been removed as the timber tables are now published by TRADA'.
TRADA seem to charge for their information, but try here
Edited by Sam_68 on Sunday 3rd October 12:40
From TRADA doc...
C16 strength grade timber can be done or C24 (stronger).
"Table 36 Permissible clear spans for joists for flat roofs with access for maintenance and repair only"
Imposed load 0.75 kN/m2.
Strength Class C16 Service Class 1 or 2
The following are okay :
63x220
75x195
75x220
C24
47x220
63x195
75x195
So should give you some options - of course the price will vary quite a bit from timber size to timber size, you might find that one of the above is cheaper than another. Of course you might be trying to fit the timber in to a specific roof height, so some may not be applicable for your use.
C16 strength grade timber can be done or C24 (stronger).
"Table 36 Permissible clear spans for joists for flat roofs with access for maintenance and repair only"
Imposed load 0.75 kN/m2.
Strength Class C16 Service Class 1 or 2
The following are okay :
63x220
75x195
75x220
C24
47x220
63x195
75x195
So should give you some options - of course the price will vary quite a bit from timber size to timber size, you might find that one of the above is cheaper than another. Of course you might be trying to fit the timber in to a specific roof height, so some may not be applicable for your use.
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff