Steel column and beams (Measuring column height)

[murphyabu]

Good morning,
I am managing an extension on my own house and trying to pin down my chosen steel fabricator to call out and measure up is proving difficult! With that in mind I am looking at confirming the measurements and placing the order. The structural engineer has provided lengths for the beams (B04 and B03 on the below) but not the column height. B03 and B04 have been designed to pickup the 1st floor cavity wall at the rear of the house allowing the ground floor to be knocked through into the extension.

The extension roof will be a warm flat roof constructed out of 47*225 joists.

B03 and B04 are to be sunk into the ceiling void to allow a flush ceiling from the existing room into the extension. To ensure its right how would you measure the universal column height based on the below images? I have exposed the underside of the 1st floor joists and also broken out the screed, but if I am interpreting the drawings correctly I also need to break out the concrete slab and then measure from the underside of the slab to the underside of the existing joists, does that sound correct?

What tolerances should I allow in terms of the column height, i.e. would it be better to be 10mm higher than 10mm too low? I will be chasing up the fabricator today to see if I can get him to visit regardless,

Thanks

 

[noseall]

Good morning,
I am managing an extension on my own house and trying to pin down my chosen steel fabricator to call out and measure up is proving difficult! With that in mind I am looking at confirming the measurements and placing the order. The structural engineer has provided lengths for the beams (B04 and B03 on the below) but not the column height. B03 and B04 have been designed to pickup the 1st floor cavity wall at the rear of the house allowing the ground floor to be knocked through into the extension.

The extension roof will be a warm flat roof constructed out of 47*225 joists.

B03 and B04 are to be sunk into the ceiling void to allow a flush ceiling from the existing room into the extension. To ensure its right how would you measure the universal column height based on the below images? I have exposed the underside of the 1st floor joists and also broken out the screed, but if I am interpreting the drawings correctly I also need to break out the concrete slab and then measure from the underside of the slab to the underside of the existing joists, does that sound correct?

What tolerances should I allow in terms of the column height, i.e. would it be better to be 10mm higher than 10mm too low? I will be chasing up the fabricator today to see if I can get him to visit regardless,

Thanks

You have to confirm ALL steel sizes on site, regardless what the drawing says. The SE however will have given you minimum end bearings to work to.
I had to work my columns out from the foundation up. I made sure I built in strict metric coursing.
Fabricators don't leave the factory. You need to pay an on-site welder/fabby fella to take control, if you'd rather not measure.

 

[cdbe]

Measure 10 times, order once!

I would dig out and cast your padstones first, your beams height will be pretty much fixed and determined by the bottom of the existing floor joists (plus a bit for beam deflection), provide steel supplier with measurements from top of padstones to underside of beams - ensure they account for the bottom plates and top connections and physically check the measurements before accepting

I would err higher rather than lower if you must - you could probably put the beams higher, or grind the padstones a bit lower if it came to it but you don't want it below ceiling height.

 

[jono_h]

As CDBE says, get your padstones in first and then it’s pretty easy. The only difference of opinion is that at a push I’d go slightly too short - the Fabricators can always make up a steel shim / packer if you’ve missed a critical height.

 

[murphyabu]

Thanks all,
Managed to nag the fabricator to the point that one of his team turned up this afternoon,

Just as well he did!

Existing walls using metric bricks (extension uses imperial), 65mm cavity existing walls (100mm new cavity), how new and existing are going to interface etc and accommodate the steels in the cavity.

He worked through the drawings with me, took the measurements etc I gave him a hand transferring levels from the first padstone poured to where the remaining two will be then and discussed a plan of attack on the installation phase.

Thanks for all the tips but that was a big weight of my back

Now to look into thermal bridging and damp courses around the padstone etc. it never ends!