6.5m Goal post RSJ

[Boney25]

Hi All,

I'm planning on opening up the rear of my house and could do with a little advice; I'm exhausting the internet and youtube.

The Structural Engineer has specified a 305x305x118 6.5m long beam bolted to the sides of two 203x203x46 columns (B6, C1 LHS and C1 RHS).

The columns are to be sat on two 1.5x1.5m 0.5m deep pad foundations, which overlap the current foundation. They have specified that the current foundations are to be replaced by the pad and dowels used to tie the pad to the rest of the foundation.

I believe the only way to guarantee the columns and beam mate perfectly is to assemble before bolting down the columns. My plan would be to lift the beam into position then raise the columns and bolt together. Once the position is set, which I imagine will be tricky due to the weight, the holes can be drilled into the pad and the chemfix anchors installed.

Does this seem reasonable?

The SE has specified 15mm of non-shrink grout under the base plate.
Does this mean I should rest the columns on a 15 mm steel spacer, plus extra to get it plumb? In which case couldn't I just get a 15 mm square spacer welded to the centre of the base plate?
I was thinking of using adjusting nuts between the pad and base plate, but once the holes are drilled I don't fancy moving the entire goal post to fit the nuts.

 

[noseall]

Hi All,

I'm planning on opening up the rear of my house and could do with a little advice; I'm exhausting the internet and youtube.

The Structural Engineer has specified a 305x305x118 6.5m long beam bolted to the sides of two 203x203x46 columns (B6, C1 LHS and C1 RHS).
View attachment 418886

The columns are to be sat on two 1.5x1.5m 0.5m deep pad foundations, which overlap the current foundation. They have specified that the current foundations are to be replaced by the pad and dowels used to tie the pad to the rest of the foundation.

I believe the only way to guarantee the columns and beam mate perfectly is to assemble before bolting down the columns. My plan would be to lift the beam into position then raise the columns and bolt together. Once the position is set, which I imagine will be tricky due to the weight, the holes can be drilled into the pad and the chemfix anchors installed.

Does this seem reasonable?

The SE has specified 15mm of non-shrink grout under the base plate.
Does this mean I should rest the columns on a 15 mm steel spacer, plus extra to get it plumb? In which case couldn't I just get a 15 mm square spacer welded to the centre of the base plate?
I was thinking of using adjusting nuts between the pad and base plate, but once the holes are drilled I don't fancy moving the entire goal post to fit the nuts.

View attachment 418885

Sounds like a plan yes.

We'd likely make the pad shape large enough so that it could accommodate the acro props whilst not interfering with the column positioning.

Dn't forget that if you are using Genie lifts they need an even base to travel on. You may need the beam in position before you start your needles and props.

shazzabeam4.jpg

• noseall
• 31 Mar 2025

bigbeam6.jpg

• noseall
• 11 Oct 2024

bigbeam5.jpg

• noseall
• 11 Oct 2024

bigbeam1.jpg

• noseall
• 11 Oct 2024

bigbeam8.jpg

• noseall
• 11 Oct 2024

bigbeam3.jpg

• noseall
• 11 Oct 2024

 

[stevie888]

That is a massive beam. Given you have no buttress on the right hand side the whole thing is acting as a sway brace which means that the columns are considerably bigger than they would be to provide simple support to a beam, but the beam can then generally be smaller than if it was just a simply supported one as the columns take some bending force. I wonder if your SE has been overly cautious? (Absolutely not a bad thing if one is going to err!)

I agree with Noseall's comments but would add the point that the 15mm grout is not critical dimension: it's there to give you some tolerance, so don't get hung up on that.

Finally, the tone of your question suggests diy? This is a mahoosive job: I'd thing long and hard about trying it.

 

[Deluks]

In the future, houses will just levitate in the air and be open on all sides.