Steel beams for lean to extension advice?

[gstyle17005]

Hi everyone thanks for letting me in the group.

Im working on an extension project. 1880 build terraced property

I have a middle wall approx one brick thick and 4m long. The wall carries on into the upper floor and in load bearing holding the front room and the rear rooms joists.

The rear wall (lean to extension) is double skinned and approx 3.6m long.

Ive had calculations done but the engineer has specifed 200x200 shs colums and 203x203x52 uc for the first wall and then the same setup for the second wall. Aswell as a strip foundation - pretty much a goal post structure without the bottom post.

Im debating would it be worth getting a test pit dug for both walls to see how deep the existing footins foundations are, the other alternatives might be to use the exisiting footings and possibly leave a nib of say 300mm at either end of the wall for a smaller size beam to sit on.
But then again it seems some reg which means if I used a brick pier for the rear wall then I would need a 656mm nib from the side walls. (possibly why the engineer suggested metal columns.

Any advice guys? THanks

 

[stevie888]

If you/ve employed an SE then you really should take his advice rather than seeeking WAGs on a forum. It will be his PI that takes the hit if it all goes pear shaped

However the sizes do seem overly big as , if you're removing the upstairs wall then the only load the first floor beam is going to carry is the first floor. Similarly the upper beam will only have roof loads.

My guess is that you want the opening as wide as possible and the steelwork is providing sway bracing too.

 

[gstyle17005]

If you/ve employed an SE then you really should take his advice rather than seeeking WAGs on a forum. It will be his PI that takes the hit if it all goes pear shaped

However the sizes do seem overly big as , if you're removing the upstairs wall then the only load the first floor beam is going to carry is the first floor. Similarly the upper beam will only have roof loads.

My guess is that you want the opening as wide as possible and the steelwork is providing sway bracing too.

hi yes that is fine but i would be getting another SE to do a seperate design rather than going with the current one, just debating if it is a good idea going for a revision.

 

[tony1851]

200 x 200 SHS columns and a 203 x 203 x 52 UC for a 3.6m span in a domestic structure is absolutely bonkers.
That's not engineering - its profligacy.

 

[noseall]

1880 build terraced property

Ok...

alternatives might be to use the exisiting footings

Good luck with that.

 

[tony1851]

His SE is certainly keeping the Chinese steel mills busy.

 

[gstyle17005]

200 x 200 SHS columns and a 203 x 203 x 52 UC for a 3.6m span in a domestic structure is absolutely bonkers.
That's not engineering - its profligacy.

I agree its an absolute joke.

Ive had a word with another se today whos happy to use brick piers, will see what size beams and pad footing he specifies.

The steels alone were coming to 3.5k

 

[gstyle17005]

Ok...

Good luck with that.

Probably little to no footings do you think?

 

[tony1851]

I think one of the problems is that today, SEs seem to be taught that if any new structure is being applied to an existing building, be it anything from a beam to an additional storey, it must be supported independently of the building.

I kid you not when I say I've seen plans for a loft conversion where the newly-qualified SE had designed the loft to be supported on four columns - cast-in-situ reinforced concrete columns, no less! - going down through the house on to separate foundation pads. It would have rendered the house worthless.
True engineering can be trying to achieve something with the resources available; one of those resources is the building istself. If an SE is not prepared to see what the building can provide, he/she is not doing their job properly and may be costing the client more money than necessary.

 

[noseall]

Probably little to no footings do you think?

For point loads - I doubt they'll be up to snuff.