redtop Posted March 19, 2020 Share Posted March 19, 2020 so will have steel RSJs which will sit on the external timber frame walls. Cripple studs underneath transferring load direct to foundation, all designed by SE. The one bit if detail missing is how we actually connect the RSJ to the timber walls, any ideas / photos? Link to comment Share on other sites More sharing options...
MikeSharp01 Posted March 19, 2020 Share Posted March 19, 2020 (edited) The SE might have specified a post cap detail probably a steel plat to spread the load if RSJ narrower than top of stud, I think there are commercial alternatives but we are using wooden beams across our posts so not up on them. Edited March 19, 2020 by MikeSharp01 Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 12 minutes ago, MikeSharp01 said: The SE might have specified a post cap detail probably a steel plat to spread the load if RSJ narrower than top of stud, I think there are commercial alternatives but we are using wooden beams across our posts so not up on them. nope, nothing. The RSjs span the distance between one external wall and the other and will then have joists and then the flat roof. So the steels just sit on top of the top plate with cripple studs underneath. Its how I then fix the steels to the top plate that confuses me Link to comment Share on other sites More sharing options...
PeterW Posted March 19, 2020 Share Posted March 19, 2020 2 minutes ago, redtop said: nope, nothing. The RSjs span the distance between one external wall and the other and will then have joists and then the flat roof. So the steels just sit on top of the top plate with cripple studs underneath. Its how I then fix the steels to the top plate that confuses me Get the steels drilled with 16mm holes in the bottom web, half the distance / thickness of your walls (ie if they are 140mm studs then holes need to be at 70mm) Then use M10 coach screws with washers through the holes into the top of the timber. If you can get all the way through - such as the timber being less than 100mm thick, then use coach bolts. Don’t crank them up tight, but enough to nip them up. Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 10 minutes ago, PeterW said: Get the steels drilled with 16mm holes in the bottom web, half the distance / thickness of your walls (ie if they are 140mm studs then holes need to be at 70mm) Then use M10 coach screws with washers through the holes into the top of the timber. If you can get all the way through - such as the timber being less than 100mm thick, then use coach bolts. Don’t crank them up tight, but enough to nip them up. thanks, that would work. The other idea that just sprung to mind, remembering that under the top plate there will be the cripple studs, was to pre-drill RSJ and then also pre-drill through the top plate into the cripple stud and resin fit a longer, say 300mm M10 bar , sit steel over bit of bar sticking out then nut on top. That way the steel is fixed through the top plate and into the cripple stud. Or is this just overkill and would I run the risk of weakening the cripple stud by drilling down through the top Link to comment Share on other sites More sharing options...
MintSprint Posted March 19, 2020 Share Posted March 19, 2020 Ask your structural engineer, but you don't necessarily need anything. Once the RSJ is under load, it won't be going walkies... Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 Just now, MintSprint said: Ask your structural engineer, but you don't necessarily need anything. Once the RSJ is under load, it won't be going walkies... SE didn't seem concerned and said leave it to timber guys lol. Link to comment Share on other sites More sharing options...
MintSprint Posted March 19, 2020 Share Posted March 19, 2020 Well, if the SE hasn't specified any restraint, then provided it's aligned correctly and with enough bearing, it doesn't need anything. It will happily just sit there... steel beams are not noted for their ability to float away if they're not bolted down. Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 10 minutes ago, MintSprint said: Well, if the SE hasn't specified any restraint, then provided it's aligned correctly and with enough bearing, it doesn't need anything. It will happily just sit there... steel beams are not noted for their ability to float away if they're not bolted down. well that's true lol. I guess my thinking was as they are forming the span from one external wall to the other they will not only take the roof load but also stop the walls spreading at the top. maybe just overthinking this Link to comment Share on other sites More sharing options...
Mr Punter Posted March 19, 2020 Share Posted March 19, 2020 The floor often holds the walls together. Link to comment Share on other sites More sharing options...
MintSprint Posted March 19, 2020 Share Posted March 19, 2020 8 minutes ago, redtop said: I guess my thinking was as they are forming the span from one external wall to the other they will not only take the roof load but also stop the walls spreading at the top. Yep, that's why I suggested to confirm with your SE. As @Mr Punter says, it is more normal for the floor to restrain the walls; it would have been conceivable (albeit unlikely) that the RSJ might have been designed to contribute to this, or to form part of a sway frame that contributed to racking resistance (in which case there'd have been a steel post instead of cripple studs and a rigid connection between the two at the top of the post), but in that event your SE would have clearly known about it. If the SE don't care, then you're safe to assume that the beam is simply supported and serving no restraining function, in which case it can simply sit there (provided, as I said, that it's aligned correctly and has full end bearing). Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 Just now, MintSprint said: Yep, that's why I suggested to confirm with your SE. As @Mr Punter says, it is more normal for the floor to restrain the walls; it would have been conceivable (albeit unlikely) that the RSJ might have been designed to contribute to this, or to form part of a sway frame that contributed to racking resistance (in which case there'd have been a steel post instead of cripple studs and a rigid connection between the two at the top of the post), but in that event your SE would have clearly known about it. If the SE don't care, then you're safe to assume that the beam is simply supported and serving no restraining function, in which case it can simply sit there (provided, as I said, that it's aligned correctly and has full end bearing). cheers, waiting for his reply, see what he says BUT he has specified steel posts and rigid connections in other areas so you are probably right. All timber frame has been glued and screwed to the floor and OSB board so don't think its going anywhere. Pic is below noting the steel in the pic isn't the one going across the roof; bit short for that ? Link to comment Share on other sites More sharing options...
Mr Punter Posted March 19, 2020 Share Posted March 19, 2020 The timber frame co should be able to give you a full set of drawings and calcs on request. Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 9 minutes ago, Mr Punter said: The timber frame co should be able to give you a full set of drawings and calcs on request. if only you knew ? No chance Link to comment Share on other sites More sharing options...
Temp Posted March 19, 2020 Share Posted March 19, 2020 1 hour ago, redtop said: will have steel RSJs which will sit on the external timber frame walls. Cripple studs underneath Not many photos out there but I found this one showing one method. I think they have chosen this method (brackets) to minimise the width. If your studs are in a wall I reckon fixing two taller studs either side so the RSJ sits in a |U| would also work. Link to comment Share on other sites More sharing options...
dpmiller Posted March 19, 2020 Share Posted March 19, 2020 sorry about the poor piccy, but we've got this. Lintel steel just resting on the cripple studs, racking steel (on a steelpost in the inside wall of the room) resting on, with the upstairs walls again just resting on. All from the drawings. Link to comment Share on other sites More sharing options...
MintSprint Posted March 19, 2020 Share Posted March 19, 2020 13 minutes ago, Temp said: If your studs are in a wall I reckon fixing two taller studs either side so the RSJ sits in a |U| would also work. Be careful of this one... it's why I'd been careful to qualify my comments above by saying that you need full end bearing, The stud cluster specified by the Engineer is what's necessary to transmit the load from the RSJ to the foundations. The bottom flange of the RSJ has to cover the entire stud cluster (and if it doesn't, it's normal for the SE to specify a steel 'spreader plate' that sits under the flange of the RSJ, on top of the stud cluster to its full width), in order to do so. You can fit extra studs to 'bracket' the RSJ, if you like, but obviously they won't be actually carrying any of its load, so you'll still need the full complement of studs as specified by the SE for that stud cluster, as well. Obviously, this arrangement locates the end of the beam side to side, but does nothing to restrain it longitudinally... but as above, it shouldn't need to. 1 Link to comment Share on other sites More sharing options...
Temp Posted March 19, 2020 Share Posted March 19, 2020 +1 Yes if the studs (and any metal plate/pad) are wider than the beam, extra stud "brackets" wouldn't serve to locate the beam as they would be too far apart. Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 (edited) SE has replied:- M10 coach screws fine for securing ends of steels. To provide the extra strength to stop the tops of the walls moving out:- the joist (which run the length of the kitchen fastened to the side of the steels) noggins (which will run in same direction as the steels) will fix back to the top of the timber wall at either end. The flat roof deck will then be glued and screwed and tie the whole thing together. make sense? Edited March 19, 2020 by redtop Link to comment Share on other sites More sharing options...
redtop Posted March 19, 2020 Author Share Posted March 19, 2020 this is his exact wording remembering its a flat (sloping slightly in one direction) roof:- M10 coach screws should be OK. The tops of the walls should also be fixed to the roof construction over using noggins between the joists to fix to the heads of the walls at regular centres. Link to comment Share on other sites More sharing options...
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