Hi
I will be installing an RSJ as a part of a project to open up my kitchen and dining room with an archway. My question is should I wrap mesh around the RSJ before installing it to enable it to be plastered or is there a better solution?
Thanks
Richard
Use a Box Lintel, ready to plaster.
Rick
sometimes they look better left raw and painted. Just clean the rust off b4 painting.
Regards, NT
If it's loadbearing it needs to be protected in some way to provide fire resistance. The usual way is 2 layers of plasterboard + skim thought intumescent paint would be an alternative way of doing this.
It's probably easier to make 2" wide wood wedges to fit the RSJ then hammer them in place. Plasterboard can then be fixed to those in the normal way. Not so much skill needed as plastering over mesh.
Thanks for your repsonses, both of you. I tried sourcing a box lintel using the same measurments I had from the strutural engineer but couldn't get one to the right spec. The spec for the universal beam is:
178x109x19UB or 12 cant read the writing very well!!!!Apparently it should be able to support 5 ton, any other ideas?
How do I go about just plastering the RSJ if Idecided just to go that route, what prep would I need to do?
The age and style of the building kinda rules out the natural look.
Also any ideas on where I can get some needles from, I'm not sure if they are known as this in the trade but I mean the wood or steel that supports the wall above by being inserted through the wall. These are then proped, what should I ask for at Travis Perkins to avoid looking like a complete pratt.
Cheers
Richard
Cut some pieces of batten, a tiny fraction longer than the space between the top & bottom of the beam (inside), hammer them in, nail plasterboard on (fold it around the bottom of the beam and up the side by slitting through one PB face).
Cut up some pieces of 4x4 or similar, possibly less. Prop as close in as you can for maximum rididity. Don't jack the house up with your props, secure is good enough.
J.B.
178x102x19 UB
Or 7" x 4" in old money
Why two layers when one is enough for floor joists upstairs ?
IIRC, the problem is that steel can warp when subjected to heat. Could be this would happen before joists would be seriously weakened by fire. The steel has to remain in the support position for a certain time.
Well, that's my theory anyway.
Hmm. I can see - and touch - the ends of the only RSJ in our extension. This is in a sort of walkway in the roofspace to an attic room at the end. The RSJ supports a small wall over a doorway which would be the main way out. I assume for safety I should be boxing this RSJ in (only been like this for 22 years !)
Can somebody point me to the actual specs for what is required ?
Steel is more vulnerable to fire than wood. Wood takes ages to burn through to the point where it fails, steel deforms much faster. ISTR a lot of discusion about the safety of steel framed buildings at one time, and a fire test being done on one. Although the steel deformed farily quickly, nothing in fact failed.
Regards, NT
"N. Thornton" wrote | > Why two layers when one is enough for floor joists upstairs ? | Steel is more vulnerable to fire than wood. Wood takes ages to | burn through to the point where it fails, steel deforms much | faster. ISTR a lot of discusion about the safety of steel framed | buildings at one time, and a fire test being done on one. | Although the steel deformed farily quickly, nothing in fact failed.
AIUI it was the failure of the fireproofing compound on the steel framework of the World Trade Center that was a major factor in the towers collapsing.
When thick wood joists burn, the outside gets charred and actually helps to protect the inner core.
Owain
Some great info, thanks.
I've found what looks like to be 4X2 wood which was left over from the construction of the garage roof (slate) would this suffice, or not man enough for the job?
And i'm assuming the battens for the plasterboard for the UB can go in after its in place, just before plastering?
Cheers
Richard
It depends on what they're holding up..... what sort of span will you have, and what's above it?
That's it. 2"x2" is probably going to be about right, chamfer off the back corners about 1/2" so it can go tight up to the web. UBs are easier to deal with than RSJs, as the flanges are parallel.
J.B.
its going to be a 6ft span and the weight is approximately 5 tons according to the structural engineer.
5 tonne just in the triangle above the span or is there a purlin or something else involved ? Either way this isn't a 4*2 job !
There is apparently a purlin which is only supported by joists so the structural engineer made allowances for this in his calculations for the new steel. So 4x4 it is?
Cheers
Richard
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