Steel size

[marsaday]

I am about to knock down the dining / kitchen wall to make a bigger room. This wall has a wall built on it above and also the upstairs floor is loading on it. so it is structural and the opening will be about 3.2m wide.

BC will be out next week i hope to give me some advise as they are pretty good on what to use. I was thinking a 7x4 might be fine.

Any ideas on whether this will be too small ?

Also does bonding undercoat stick to steel for when i come to plaster it out. Do people use this to do the job or just use plasterboard ? If so how do you stick the PB to the steel ? Do you use PB adhesive ?

 

[DiscoDancer]

Sorry I can't comment on the size of the steel.

When I did our extension I used an "I" section steel. Then I wedged some pieces of timber in each side, leaving a little sticking out each side. I think I used lengths of 75X50.
I was easily able to screw plasterboard to these pieces of timber, both sides and bottom.
For fireproofing I used two layers of plasterboard.
So, if you are attempting to make the steel flush with both ceilings, bear in mind the double thickness of plasterboard.

 

[noseall]

Once your structural engineer has surveyed the job and ascertained that the found's are suitable and has specified the beam size, pad stone size and delivered the calc's, I suggest you get the web drilled and install a timber sandwich each side of the web.

 

[marsaday]

Not using SE. BC normally tell me what is acceptable and i over spec. Pretty std stuff really on this 1930's semi.

 

[RonnyRaygun]

A 7x4 might b OK, but it could be tight depending on the loads.

Do as Noseall says for fixing plasterboard.

 

[noseall]

A 3.2m structural opening is not standard stuff.

 

[marsaday]

Ok, i will get the steel drilled and understand about fitting wood into it.

Maybe an 8 x 4 will be a better way to go. I will see what BC are happy with though.

 

[marsaday]

Well i can always shrink it down a touch in order to make life easier. An opening of 2.7m would be fine.

The neighbour has done his and i am pretty sure they just rammed in a load of steel without any SE calcs.

BC may say you need calcs on this one, but i cant see it. They are pretty relaxed.

 

[datadiyer]

I don't know what your BC are like, but a while back, they would only let me remove a chimney breast on a 1930's semi if I installed 3 x 8 by 4 steel, talk about over engineering! Mine said he would advise me what to install, but ended up not removing chimney breast due to extreme cost. Hope your BC are less strict, good luck.

Cheers,
Datadiyer.