extra long load bearing RSJ - cost/complication??

[mrds]

Hi all,

I'm looking to remove the loadbearing wall between our kitchen and diner. It has a chimneybreast and is approx. 4.2m long.
I had a chat with a structural engineer and he said that this size span would also need vertical steels at the ends of the beam to support the weight and tie it to the foundations.
There's a lot of examples on t'web about the cost and complication of removing a smaller wall, but I can't find any examples of the cost for this type of build. Does anyone have any idea of the ballpark? Could make all the difference between doing the work and not!
Also, is it best to ask a standard builder to do the work, or get a structural specialist. I'm a bit nervous about them supporting the structure properly, and let's face it, we've all heard horror stories!!!

Any help much appreciated, thanks!

 

[garyo]

try searching for 'goalpost rsj' and you should find some better results - seems to be the term used for this kind of design.

Gary

 

[^woody^]

I'm not so sure that it "needs" goalposts, more likely the engineers software and limited ability to calculate have formed this conclusion

 

[theoldun]

Hi all,

but I can't find any examples of the cost for this type of build. Does anyone have any idea of the ballpark? Could make all the difference between doing the work and not!
!

Sorry not on the information given. Would need to know the following.
Is wall half brick. Is breast on one side of wall only. Projection of breast from wall. Width of breast. Is there abreast on first floor above or just a single flue with a projection of 300mm and width of 450mm. Does the wall support floor joists. London. What part and have you room for skip, or is it bag up job and dispose on the day?
Regards oldun

 

[tony1851]

I think Woody is spot on in this.Time and again on this forum we see structural engineers being - well - just lazy, and charging handsomely for it.
What your SE has suggested is a rigid frame, aka as 'goal post'. These are generally only necessary when the stability of the building as a whole will be affected by removal of a wall.
With your span (4.2m is not long) and with how you describe the work, I would think it unlikely you would need a rigid frame, rather than just a simple beam on adequate padstones.
These frames are expensive, but your SE wants you to pay
through the nose so as to make life easy for himself. Typing a few figures into a program is not engineering - its lazyness. Get another SE

 

[RonnyRaygun]

It's not a particularly long span.

As Tony said, goal post frames are usually used to maintain lateral stability when certain walls are removed.
Sometimes the high load from above can mean that bearing directly onto walls either end is not desirable as masonry or (more likely) the foundations will be overstressed. It depends on how much the load can spread onto the wall and foundations below. Your beam will be carrying quite a lot of load as it will at least be carrying a wall and a chimney breast.
However, if this is the case, a much better option to use a box frame, (goal post with a base beam) as this arrangement allows the load to be spread back along the existing foundations, and doesn't place any extra stress onto the existing brickwork or foundations.
In this scenario a goal post arrangement would need its own new pad footings.

It's difficult to say for certain what is required without a lot more information.

 

[tony1851]

Ronny; I agree with what you say structurally, but from the OPs perspective I wouldn't necessarily assume he needs a goal post (we only have his SEs word for that)
From my own experience in many instances, I've found that it's possible to avoid a frame and prove stability by using the counter-balancing effect of the loads on the remaining walls. Trouble is of course it's a PITA to calculate; and the OP would probably be persuaded by the SE that it needs a frame.

 

[theoldun]

Without wishing to be disrespectful, whilst it is always interesting to read technical discussions, we were under the impression that the OP was seeking a ball park figure to decide whether removing the wall would justify the initial outlay.
Regards oldun.

 

[tony1851]

Without wishing to be disrespectful, whilst it is always interesting to read technical discussions, we were under the impression that the OP was seeking a ball park figure to decide whether removing the wall would justify the initial outlay.
Regards oldun.

Agreed, but the point is that it would make a big difference to the cost if he did not in fact need a rigid frame.

 

[mrds]

Guys,

Many thanks for the responses. I had kind of taken the SE's advice for granted, you have provided a lot more info and different viewpoints (Ain't forums great!). In fairness to the SE, this was all a conversation over the phone before I committed to spending £660 on the report, which might be a waste anyway if the work is £1000's due to the extra steelwork. The catch is that the cost of the report will depend on the required solution. So does anyone have an idea of the cost of the building work for a goalpost type structure?

 

[jeds]

Goalposts won't add that much. Cost of columns and fabrication, which in most cases would be three or four hundred quid. If you need pad foundations that could add double that amount depending on the situation below floor. I also agree that goalposts are not likely to be necessary.