I am designing a conservatory that I intend building using 24mm double glazed units for the roof. One of my choices is to support the glass on timber rafters and with that in mind I have searched Googl,without any luck,to find suggested rafter sizes for various spans and fixing cetres. The span will be about 4 metres and unit fixings will be
600mm. Does anyone know the whereabouts of tables etc to help me out here?John East Devon
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Have you looked at the tables in the Building Regulations Approved Document A. (I haven't either). They have tables for rafters in there, but you would have to check that they cover the correct deadweight for double glazing.
Christian.
Sir
There are people who sell self supporting, self sealing glasing bars for this type of application, however I forget the name, try goole.
Rick
IMMing a message "A Wannabe" wrote: news: snipped-for-privacy@4ax.com
The loading isn't going to be much different to that of a tiled roof. In fact most probably lighter and of course much more rigid. However this is no reason for cost cutting and using 3 x 2's as the flexing of double glazed units is what causes them to fail eventually.
If you use larger than 5 x 2 it might look too chunky. How about reinforcing the rafters with steel bar which would double as rebate?
What sort of a slope is the roof to have?
If and when you do find out, please let me/the group know as I have a very similar requirement although probably less immediate than yours as I have to go through the rigmarole of Listed Building Consent first.
Fash
Try
Fash
Thanks for all your replies, sorry for the delay in getting back I've been slaving over a hot drawing board.
"Christian McArdle" suggested:
Yes, they suggest that I would not get away with anything much less than 50x150mm (2"x6")
Rick Dipper helped with:
I have googled and found about six companies and already have a price for a complete roof frame minus glass at about £1,000 + vat. I do fancy the look of perhaps varnish wood though and would sit glazing bars on top to make the whole weatherproof.
Michael Mcneil added:
Precisely my concern.
Not too worried about chunkiness but of course it will cut out light somewhat.
Or tensioning bars as used in Victorian greenhouses.
About 17 degrees.
Stephen Fasham wanted to know:
Will do.
And
They are on my list. I shall check if they have carrying loads of rafter sizes.
John East Devon
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