Hi, I'll soon be starting work on an old terraced house, standard two bed and box room, The house will be a complete gut job & I'm hoping to install an rsj but then fit the new joists into the web of the rsj by notching 8mm off the top & bottom. Thus hiding it instead of having to box it in, the rsj I thought of installing would be an 8inch square so the joist would be sitting 3.5 - 3.75inch the rsj is spanning 4.5mtr room. & joist spaning 3.9mtr either side, does any one think this would be ok?
Joist fitted to rsj
- Thread starter Ryanjl87
- Start date
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You don't say what depth of floor joist you are using, though it looks like you're using an 8" x 8" x 46 steel beam. If you notch the bottom of the joists by 8mm so as to bring them flush with the underside of the flange, you may find that after the timber shrinks slightly (as it will do when the heating is on), it pulls the plasterboard up slightly and you get a slight bulge in line with the underside of the steel. To avoid this, you need to notch them about 12-14mm. You would probably have to use 9 x 2s to allow for being higher than the top of the beam as well.
The width of the bottom flange is OK for bearing, but suggest putting short blocking pieces up against the web and between the joists to maintain them in line.
The width of the bottom flange is OK for bearing, but suggest putting short blocking pieces up against the web and between the joists to maintain them in line.
9x2 I would use, I forgot to mention it (new there would be something) I was hoping to use 8x2 but they wud be slightly smaller as the wood is planed & it would not allow for expansion/contraction as you said, & I was thinking the same with the packers stop any movement, I was then thinking of covering everything with a fire retardant material & using the fire boards for underneath the joist, atleast BC won't turn up saying it's not good enough 
have you seen/heard of this befor?
have you seen/heard of this befor?
The pink Fireline board would be fine.
Don't forget to include some strutting at mid-span of the joists to keep the inspector happy.
Don't forget to include some strutting at mid-span of the joists to keep the inspector happy.
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I won't, I'll be ordering some lengths soon found a good place near me £14 for 4.2mtr length, any idea what to cover/coat the ends in which sits in the pocket of the wall, I was thinking bitumen or something similar. Also would you use c16 or 24?
If the joists are going into an external wall, most builders wrap the ends in dpc material (the black polythene stuff) and staple it on.
C16 would be OK for that span.
C16 would be OK for that span.
ok thanks for that your input it is much appreciated. other people iv spoken to seemed optimistic with the amount it would sit on the rsj, but like i said to them when you use joist hangers the timber only sits on about 2.5inches then. better start ordering materials then
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