Loft conversion Joists

Postby peewackadingdong » Sat Dec 13, 2008 12:16 pm

:lol: Hi my name is peter i'm thinking about putting flooring into the loft as it stands I have 17 joists just under 7m long they are 50mm wide and 75mm deep the gap between them is 360mm. By the chart i've found on here I see the depth has increased to 97mm and the spacing to 400mm. How should I go about putting new joists along side my old ones ie the 22mm height difference. My second question is how much do you think I should pay for the wood.

many thanks for any help given

peter newbie
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Postby stoneyboy » Sun Dec 14, 2008 1:17 pm

A lot depends on the arrangement of the support walls below your loft, clearly you cannot have a clear unsupported span of 7m with the existing joists. What are you going to do with the loft and do you want to increase the amount of insulation.
If your new joists were run on top and at right angle to the existing you could then add 175mm of mineral wool insulation which would make large savings on your heating bill. Screw the new and old joists together at every cross point and you will end up with a reasonably stable floor.
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Postby peewackadingdong » Mon Dec 15, 2008 11:19 am

Hi I wanted to start to convert into a bed room over a long period of time so first buy and fit the joists the ones up there are just to hold the ceiling up but I need something more stronger for a bed and the like
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Postby wmlserv » Wed Dec 17, 2008 7:02 pm

Hi, I would like to know what exactly is the minimum sizes (depth,width,spacing) for a floor joist when converting a loft space. I currently have 3"x1" ceiling joists and would like to replace these before having a Dorma done by my friend who is a roofer. The span is approx 3m and would be supported by the external wall and an internal supporting wall. I hope someone can help. Thanks
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