setting up of acrows strongboys.

[damo152003]

Hi guys im building a side extension and knocking through the kitchen wall. i need to install the steels with the wall in place still. The property has been extented to the rear before so that steel is going to sit in the eye of the new beam were fitting.
The joists will sit on top of the new steel installed.
i want to know if i can set strong boys up between the joists picking up bothe walls and and acrow the joists up with a scaffold board.
All this from the inside so it means i can install the steels from the outside leaving the wall in. The cavity is 50mm wide
I hope this makes sense.
The outer leaf wall is taking the weight of the roof inner leaf is the floor joist. Thanks in advance i know ideally i would just acrow both sides but i dont think there would be enought room between the prop and wall to be able fit the steel in to lift up.
The opening is 4m .

 

[^woody^]

Is the wall cavity or solid? If solid, what bond is it?

 

[damo152003]

Thanks for the quick reply. Its cavity wall with 50mm and 100mm bricks i rang a tool hire earlier and they said the strong boy is 300mm long. Cheers Damien

 

[^woody^]

Strongboys are not designed to reach the far leaf of a cavity wall, and probably wont fit anyway - the angle piece gets in the way of the beam or wall and the end does not catch the second leaf.

The joists will hold the inner leaf, so you'd prop them. If there is a flat roof built into the wall you's prop that.

Or you need to needle through above the flat roof/ceiling and floor if strong boys wont fit each side.

 

[damo152003]

ok thanks. Needles i guess will have be an option uat hoping they will fit between the joist aas the bathroom ablove is all done!.
There is no flat roof its the roof of the house which sits on the outerwal.
What size steel would you use? I asked my S.E suure he said 156 something but they have
gone closed now so cant ask the question!

 

[damo152003]

Manages speak to S.E going for 152x152x37kg/m in planning on 4 needle for the 4m span plus acrowing the joists too.
Going put the needles between the joists is that ok todo.?thanks

 

[^woody^]

Has someone actually designed these beams? They seem an odd choice for a 250mm wall and at that span.

 

[damo152003]

Hi woody, That steel size is for the needles mate.This is what my S.E has said will be required.
Not sure what you mean by odd? Not big enough or to big?
Cheers

 

[^woody^]

I thought the steel was for the beam. Who specifies steels for needles? A couple of 4x2's nailed together normally does it.

 

[damo152003]

lol its because my replies are all over the shop!
well they will be plenty strong enough then and 170 quid lighter too!!
I will stick the needles between the floor joist to hold the upper walls hopefully this will save having punch holes through the wall in the bathroom above!
The steels for the span are 305x 127-43kg/m
putting the needles inbween the joists should be a problem should it?