Getting BC to decide between 2 engineers?

[nervous123]

Some of you may recall I had my dining room enlarged by some cowboys who never involved either a Structural Engineer or BC.

I have since had 2 S Engineers to inspect, with a view to having it regularised.

One (not chartered) calculated the loadings and then prepared calculations. He says the beam is too small and insists it needs to be replaced.

The second (chartered, double the price and half the interest) used the first one's loadings, did his own calcs and says the beam is fine. But he seemed much more casual and disinterested - (I had to drag him round the house to look at the roof and attic loadings etc)

I have submitted the 2nd one's calcs to LABC in the hope that they will merely approve the beam and not require replacement. However I do have concerns as the first engineer was quite insistent his calcs were correct.

If i explain my doubts to BC, will they just err on the side of caution and make me replace the beam? Or will they be objective and if the second engineer is correct that the beam is fine, agree to him?

(NB The issue is compounded by the fact that BC have requested details of the loadings, which I only have from the 1st engineer wherein he recommends replacing the beam! I could of course copy and paste them selectively though)

Thanks for advising.

 

[jeds]

What size beam is it and what span?

 

[nervous123]

It's a 152 x 152 (x 23 or 30 acc to 1st and 2nd engineer respectively).

Span is 3.5m

1st engineer says it is laterally unrestrained, second has written it is restrained.

Loading data, which both have used (but prepared by 1st one) is 11.81 dead kN/m and 7.63 imposed.

 

[freddiemercurystwin]

They both have PI presumably?

 

[nervous123]

They both have PI presumably?

The unchartered one does not. (Incidentally, he contributes to this forum occasionally)

I think the chartered one does, but not sure.

Will names help? Are you familiar with london engineers?

 

[freddiemercurystwin]

Will names help? Are you familiar with london engineers?

No, the DIYnot member won't thank you for it either!

 

[nervous123]

Will names help? Are you familiar with london engineers?

No, the DIYnot member won't thank you for it either!

Ok. On second thoughts not a good idea re the other one either ('casual'a and 'disinterested' hardly a warm recommendation)

Nonsense aside...what do you recommend?

 

[jeds]

The 30kg size passes easily. The 23kg passes as long as it is restrained. The degree of restraint is always an issue. Timber floors are not normally classed as fully restraining and most texts advise treating them as unrestrained. There are those however that do say tiumber floors are perfectly adequate restraint in domestic situations.

To be 100% sure you could check to see if the beam is a 30kg? The flanges on a 23kg beam are 6.8mm and on a 30kg beam they are 9.4mm, so it should be fairly obvious which it is. If it's 30kg you are absolutely fine.

 

[tony1851]

Timber floors are not normally classed as fully restraining .

jeds is correct; see attached extract from a steel manual; go for the 30kg to play safe.

Untitled

• tony1851
• 4 Apr 2012
• 1

 

[nervous123]

The 30kg size passes easily. The 23kg passes as long as it is restrained. The degree of restraint is always an issue. Timber floors are not normally classed as fully restraining and most texts advise treating them as unrestrained. There are those however that do say tiumber floors are perfectly adequate restraint in domestic situations.

To be 100% sure you could check to see if the beam is a 30kg? The flanges on a 23kg beam are 6.8mm and on a 30kg beam they are 9.4mm, so it should be fairly obvious which it is. If it's 30kg you are absolutely fine.

The flange (on the exposed side at least -can't see the other one) is 6.8mm. Does that def mean it is a 23kg?

I have asked the SE to clarify why he submitted calcs to the BC for a 30kg and if he is wrong I would demand a refund or at the least revised calcs for free.

More to the point how much faith can I place in a SE who gets this wrong? Either incompetence or something worse, I dont know which

 

[jeds]

If it's 6.8mm it's definitely a 23kg beam. What is the makeup of the loadings?

 

[nervous123]

If it's 6.8mm it's definitely a 23kg beam. What is the makeup of the loadings?

Hope this is clear - if not I will repost with appropriate spacing

LOADING DATA

UDL Dead kN/m Imposed kN/m

FROM LOFT 0.5 x 8.0m x 0.5 (0.25) kN/m2 2.00 1.00
FIRST FLOOR 0.5 x 8.0m x 0.5 (1.50) kN/m2 2.00 6.00
SPINE WALL 2.85m x 2.6 kN/m2 7.41
TANK IN ATTIC 2.5 kN / 4.0m 0.63
BEAM SELF WEIGHT say 0.4 kN/m 0.40

Total 11.81 7.63
(16.53) (12.21)

 

[^woody^]

Lateral restraint of a beam

From an appeal determination [45/1/209] in respect of removing a wall and installing a steel beam to take the first floor load

" .... original proposals were the subject of a full plans application and incorporated the use of a 203 x 102 UB beam. This application was rejected by the Borough Council on the grounds that because inadequate lateral restraint was being provided to the top flange of the beam, this size of beam would fail in bending

In the Borough Council's view, this restraint could be provided by locating and fixing the beam tightly underneath the floor joists"

 

[nervous123]

If it's 6.8mm it's definitely a 23kg beam. What is the makeup of the loadings?

John, would you mind providing me a link which I can refer the SE to, to prove it is a 23 not a 30.

I trust you - not him - but it would help my case if I had supporting documentation

many thanks

 

[nervous123]

Also, more importantly, do I :

let BC make their decision based on the erroneous belief that there is a 30 beam there

or

get SE to resubmit calcs for a 23 // tell BC that SE was mistaken

??

The whole thing is rapidly turning into a disaster unfortunately.
One wonders what the point of being chartered is.