cost to fit steels

[millibum]

Hi,

I have recently started a self build extension and had originally costed in for a single steel (254UC) across the knockthrough / opening. Our structural engineer has however told us that due to the size of the opening (6.3m) and the quality of the brickwork on either side (terraced house) he would recommend a box frame of 254 UC top and bottom (107kg) and verticles of 152 UC.

Not wanting to bring down the whole house (and the neighbours) we will of course be getting builders in to do this work but what I wanted to know is roughly how much i should budget for this work.

Thanks

 

[tim00]

I presume that you are asking for a rough price for erecting a double steel box frame only? Whatever, so much more info. pics, and actual scanned specs would be required to hazard even a guess. Others may feel, or be, more competent than me, but i wouldn't know.

As you noted, dont attempt this as a self-build - you might be well advised to pay a SE a half day's pay to come on-site and supervise the erection and installation of the steel.

 

[tony1851]

As there is a horizontal steel at the base,presumably your SE has designed a 'moment frame', aka 'goal post'. If so, the purpose is not just to support the load above but also to prevent any 'sidesway' of the house.
In this case, the connections between the horizontals and verticals have to be properly designed and detailed; this entails cutting, drilling and welding of steel plates and is expensive work. You need to get fully detailed drawings from your SE and to ask several local fabricators for prices; I would guess the steel alone would be 2-3K, without the fabrication work.
Have you thought of building brick piers at each end.? If they were properly designed, you would probably only need 1 steel (instead of 4).
As the previous poster said, 6.3 m is a fair span and you need to consider if this is within the realm of DIY.[/b]

 

[millibum]

We did enquire about a single steel with brick piers but the SE advised that due to the quality of existing party walls we we need significant pad foundations of 450mm out, 1000mm deep and 2000 wide. This is why he really wants to advise us to go with the full box frame.

Just to be clear - we are building the extension but have absolutely no intention of making the steels and knockthrough part of the DIY project. This is why I would really welcome some advise as to what kind of price I am looking at for this work. I had estimate c£2.5k for the actual steels so fits in with your estimate. I know a proper quote would require more detail but if anyone has any experience so as to give me an idea as to what to budget I would be grateful.

Thanks

 

[tony1851]

You are wise letting someone else assume responsibility for the fixing of the frame.
As regards the cost of fabricating the steel, I've known quoted prices on this vary by a factor of 2. It's not possible to get a price on this unless you can supply a fabricator with proper details of the connections designed by the SE.
For example; the fabricator will need to know the size and thickness of welded end-plates; the numbers, sizes and types of bolts (some connections of this type require friction-grip bolts which are expensive); there may also be welded web-stiffeners required. All of this affects the price and depends on what the SE has specified.

As a ball-park figure for getting the frame made and into position, I would be surprised if you had much change out of 5K.

Propping a wall of that length in what may be poor brickwork needs care and as the previous poster said, paying a SE to be on site and advise would be prudent.
Good luck.