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Urgent question re: RSJs. Any structural engineers in the house?
James - 20/2/14 at 11:33 AM

Bit of an urgent one this...


My Sister-in-law has a couple of RSJs left over from some building work she's just had done, but they need to go in the next couple of days as she's selling and has viewings!

At my house I'm considering doing 2 jobs that will require RSJs. However, we've not managed to find a structural engineer yet.

The 2 jobs at mine are:

A) remove an internal, ground floor, supporting wall that's 4m wide
B) widen the patio door (2 story house) from 2m to 3m

I can't confirm what sizes we need until we have the Structural Engineer but I don't want to get lumbered with the RSJ (£200 for the large, £85 for the small) unless there's some hope they're approximately the correct sizes!

The smaller one (suitable for the wall removal?) is 200mm tall, 8mm thick
The larger one (suitable for the patio door widening?) is 250mm tall, 16mm thick on the vertical and 10/12mm thick on the horizontal.


Don't worry! I'm not going to use these for definite without the say so of the SE. It's just whether they're about right and I should pay for them.

What sizes were used in your house for similar work?

Thanks!
James

benchmark51 - 20/2/14 at 12:05 PM

When I did my house I replaced all the lintels above doors and windows (on the ground floor)
myself. However I took advice from a competent builder, of what to use and how.
25 years later all still there and ok. I would ask a recommended builder, as it's not that
difficult a job.

twybrow - 20/2/14 at 12:15 PM

No one can say with any degree of certainty what will suffice - that is why you employ a structural engineer. There are so many factors, such as what loads are bearing on those walls, how the joists are positioned, position of chimneys etc - too many factors to be able to say 'yes that'll do!'.

How will your sister dispose of them if you don't want them? You could buy them from her and then just sell them on if you SE tells you they are not suited...?

designer - 20/2/14 at 12:24 PM

Just take them and keep them until you know if you can use them or not

mcerd1 - 20/2/14 at 12:36 PM

quote:
Originally posted by James
The smaller one (suitable for the wall removal?) is 200mm tall, 8mm thick
The larger one (suitable for the patio door widening?) is 250mm tall, 16mm thick on the vertical and 10/12mm thick on the horizontal.


sorry can't really advise you on what beam sizes you should use (I deal with industrial stuff not houses)

but i can tell you the beams are probably not RSJ's (unless they have tapered flanges)
these days they are far more likely to be UB's (Universal Beams) or UC (Universal Column) with parallel / constant thickness flanges

although every builder in the country will still call them RSJ's - its a bit like calling you dyson a hover


from the sizes above I'd guess the small one could be a "203x133x25 UB"
which is 203.2mm tall, 101.8mm wide flanges, 7.8mm thick flanges and a 5.7mm think web and 25 kg/m

and the large one could be a "254x146x43 UB
which is 259.6mm tall, 147.3mm wide flanges, 12.7mm thick flanges and a 7.6mm think web and 43 kg/m
or a 254x254x89 UC
which is 260.3mm tall, 256.3mm wide flanges, 17.3mm thick flanges and a 10.3mm think web and 89 kg/m


but even allowing for the tolerances your sizes don't match up exactly to any of the RSJ's, UB's or UC's so you'd really need to check this


here is a list of available sizes for you to try and match them up:
UB's linky

UC's linky


also the are most likely to come in grade S275-JR or S355-JR steels, hopefully it written on them (along with the actual section size if your lucky)

[Edited on 20/2/2014 by mcerd1]

MP3C - 20/2/14 at 12:37 PM

I'm a building surveyor, and would recommend the structural survey first. There are lots of different factors that enter the equation such as the thickness of the walls, if you have any point loads, live and dead loads etc. + the price that presumably you are going to buy them for £200 for example, that is near enough to the price you would pay anyway which means it would be recommended to wait until you have had the report and spend say £40 extra on a larger one that will be more suited.

+ you might even need two depending on the thickness of the wall (not for structural support - just to even the load distribution over the rsj as presumably they are 100mm width)

Hope this helps.

Matt

DW100 - 20/2/14 at 03:42 PM

I bought a 305 x 127 UB37 3450mm long last year for £160 inc vat primed.

James - 21/2/14 at 12:04 AM

Looks like general concensus is not to bother then!

Thanks for the advice all- much appreciated!

Cheers,
James


EDIT: girlfriend tells me that she's booked an SE for tomorrow so it might work out anyway! lol

[Edited on 21/2/14 by James]