Sunday, 4 September 2011

installing the floor joists to a loft conversion

now that the RSJs are in, we can start putting in the floor joists into the loft conversion. in each of the steels we are going to fix a length of timber, if the steel fabricator hasn't pre-drilled the steels, you must do this now with a mag-drill, a 14mm hole every 400mm centres. it's a good idea to mark out where your joists are positioned on the steel before you drill to avoid putting a hole where a joist will be. once the steels are drilled cut a timber to the required length, the timber should be slightly narrower than web of the steel and the same depth, for example if the internal measurement of the steel is 8" and the depth is 2" then you should use a 7x2 length of timber. place this timber into one of the floor steels clamp into position a mark out the drilled holes through the steel, then drill the timber with a 14mm bit. place the timber back into the steel and bolt together using M12 bolts, nuts and washers. repeat this process with the other floor steel.

we can now start installing the joists, if you haven't already done so mark out the position of the joists at 400mm centres. cut the first timber to the required length(the distance between the two steels) and fix either side using jiffy hangers and repeat with the remaining joists. remember to double up the joists where the stairs are going to be installed, and to treble up the joists under the dormer walls of our loft conversion. once the joists are in all that remains is the noggins cut and fix the noggins approximately every 1200mm, a good idea would to smear "grip-fill" on the joints where the noggin meets the joists, this will prevent any creaks on the floor. if you have any questions on this post, or need advise on a loft extension please send me an email.


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