Wall thickness and RSJ

longwalks1

I’m planning to open up a 3M gap on an external wall to fit folding doors. Have had drawings done by a structural engineer and need to order the RSJ, which has an 8mm steel plate welded to the bottom of it (offset).  The offset isn’t specified on the drawing.  I asked the SE and was told the offset is determined once the wall is akro’d up and opened up.  Surely then that means the house is propped up for several days or more while the REJ is made? 

Is this normal? The house wall is 300mm thick.  It’s part of an extension done in 2000.  Im assuming 100mm red brick, 100mm cavity or insulation and 100mm block?

stuart45

If you know the wall's construction the steel can be ordered in advance.
Sometimes helps to put it inside the acros first.

longwalks1

Thanks Stuart, that’s what my builder said.  Does the 300mm plate on bottom of the RSJ sound right, if it’s a 300mm wall thickness?  

Section62

longwalks1 said:

I’m planning to open up a 3M gap on an external wall to fit folding doors. Have had drawings done by a structural engineer and need to order the RSJ, which has an 8mm steel plate welded to the bottom of it (offset).  The offset isn’t specified on the drawing.  I asked the SE and was told the offset is determined once the wall is akro’d up and opened up.  Surely then that means the house is propped up for several days or more while the REJ is made? 

Is this normal? The house wall is 300mm thick.  It’s part of an extension done in 2000.  Im assuming 100mm red brick, 100mm cavity or insulation and 100mm block?

Are you intending to DIY this?  It is a major piece of work to undertake if you haven't done anything structural before.  Responsibility will be fully on you if anything goes wrong... most people want to share that with a professional with adequate insurance cover.

stuart45

longwalks1 said:

Thanks Stuart, that’s what my builder said.  Does the 300mm plate on bottom of the RSJ sound right, if it’s a 300mm wall thickness?  

For a 300mm wall the plate can be a bit less than 300mm as the face brickwork will overhang it a bit. The steel firm will know this.

longwalks1

Thank you again everyone.
section62 - I’m using a local builder but just wanted to make sure everything’s right for when the work starts.  

Stuart45 - many thanks, I spoke with the beam manufacturer again and they’ve confirmed the standard offset for the dimensions I supplied.