concrete ceiling reinforcement and non-structural wall

[bsmith]

hi there,

I am planning to do some works on my ground floor council flat. As part of this i plan to remove a wall separating the kitchen and living room. I commissioned a report from a local structural engineer to check whether this wall was non-structural (I believed it was) and his report confirmed this.

The wall in question is 60mm thick and constructed of some form of brick (the report stated clinker brick). Both floor and ceiling are concrete. The surrounding walls are all 190mm thick. The total width of the wall that will be removed (inc door) is 3.5m. The length of the unified kitchen/living would be approx 8m.

I applied for both planning permission and building control, as my initial plans included unifying two of the bedrooms. Permission was granted for both (the structural engineer's report was included in the submitted documentation).

I have now applied to the freeholder (the LB council housing assoc) regarding permission for this work, so that the lease can be amended to reflect the changes. Their surveyor inspected the property and stated that evidence will be required that the steel reinforcement in the ceiling concrete runs in the same direction as a the wall i propose to remove, rather than perpendicular to it. Alternatively he proposes a have a beam placed along the ceiling in the same location as the wall (I don't want this).

Though I'm not a structural engineer myself I am certain that the wall concerned is non-structural. My neighbours (who have not gone through this process) made the same alteration 3-4 years ago without impact to their flat or their neighbours above. My surveyor is adamant that the wall concerned is non-structural and placing a beam there would be of no structural value. He has suggested digging into the ceiling to determine the direction of the reinforcements.

Ok, enough preamble.

My question is this: Is digging into the concrete ceiling a common way to determine the direction of the steel reinforcement supports? (Presuming that documentary evidence about the construction is unavailable)
Is there a non-invasive way to determine the same information? Some sort of electrical device?

I am separately exploring other possible avenues such as obtaining the original engineering drawings (unlikely, it's 70's build) and getting the structural engineer and the surveyor to meet.


many thanks in advance

 

[Static]

Refer the question to your structural engineer for him to have a little laugh at and formulate a suitable letter response.. may charge you £50 for a bit of his time tho..

 

[russellasmith]

With out knowing the size direction and spacing of any reinforcement and the thickness of the reinforced slab I dont see how your engineer can know that the wall was not there to reduce the span of the reinforced slab, he's therefor only guessing. Council houses are natorious for there poor constructions

With details of the reinforcing he can calculate the distance the slab will span.

 

[tony1851]

I dont see how your engineer can know that the wall was not there to reduce the span of the reinforced slab.

If the wall is only 60mm thick, then assuming a floor-ceiling height of around 2400, it would appear far too slender to provide adquate support for a r/c slab.plus live load etc.

 

[^woody^]

Any reinforcement will span in the longest direction of the beams (eg bison) or be a mesh grid if the floor is cast in-situ

The HA surveyor is an idiot. Removing a no load bearing wall has no effect on a floor in a residential flat

 

[bsmith]

All,

thanks for the feedback.

THe question is though:

is it possible to determine or prove the direction of support of the reninforcement in a concrete slab?
The structural engineer has suggested boring into it to physically check. Is this a common practice in this sitation?
Without having the engineering digrams available is there any other way to detmine this information?

Static - i'm in dialogue with the structural engineer at the moment. If the cost was on £50 then I'd pay and be done with it. I suspect all this may cost significantly more so i'm trying to establish the best way of getting agreement from the HA at minimal time/cost.

^woody^ - it's the ceiling the HA surveyor is worried about. Maybe i misunderstand but wouldn't reinforcements span the shorter distance across a rectangular space.

tony1851 - agreed and as stated this wall was removed from my neighbour's flat over 3 years ago and there have been no issues since, though this is of no value as formal proof.

 

[^woody^]

^woody^ - it's the ceiling the HA surveyor is worried about. Maybe i misunderstand but wouldn't reinforcements span the shorter distance across a rectangular space.

If this is a pre-formed beam floor, the beams will normally span the longest distance and be something like 9m x 1.2, so the reinforcement goes with the longest span

They may span the short distance but that's normally uneconomic so not often done

The point is the reinforcement direction is the same as any beam, so if there are some construction joints visible that helps

If you can post an external picture of the block, or a similar block, then that may help in identifying the system used

But read this recent thread on a similar situation and my posts towards the end. //www.diynot.com/forums/buildi...tion-regarding-load-bearing-situation.312635/

Basically its not for you to certify or prove anything, and TBH, invasive testing of the flat could be against your tenancy/lease agreement and I am surprised that this was suggested by a HA employee

 

[bsmith]

The point is the reinforcement direction is the same as any beam, so if there are some construction joints visible that helps

If you can post an external picture of the block, or a similar block, then that may help in identifying the system used

Thanks. I'll take a picture and post this evening.

But read this recent thread on a similar situation and my posts towards the end. //www.diynot.com/forums/buildi...tion-regarding-load-bearing-situation.312635/

thanks for pointing this previous thread out. I'll go through this this evening - hopefully it will give some light on the matter.

Basically its not for you to certify or prove anything, and TBH, invasive testing of the flat could be against your tenancy/lease agreement and I am surprised that this was suggested by a HA employee

The HA is currently insisting on a condition being inserted into the licence for alterations that "demolition of the wall does not adversely affect the property" and calculations to that effect are provided by a structrual engineer. I've already tried to argue with that that the existing report is sufficient but so far they aren't having it.
It was my structural engineer who suggested invasive testing but this sounded quite extreme to me, hence my question on the forum.

 

[^woody^]

The HA is currently insisting on a condition being inserted into the licence for alterations that "demolition of the wall does not adversely affect the property" and calculations to that effect are provided by a structrual engineer.

There is normally a presumption in these types of requests, that permission is not unreasonably withheld and/or that restrictive pre-conditions are not imposed

As a local authority/HA the landlord has key information about the properties they own. Therefore it is both safe to assume and reasonable to expect that one of their "professional" employees can deal with this request and do the necessary investigation (a site visit and a check of any records) and grant or refuse the request for valid reasons. It is not that difficult

In insisting that you prove via calculations that this work wont affect the building the HA is acting unreasonably. This is because, for you to prove this you need to [potentially] engage several different people (engineer, builder for samples, testing lab), and then you need to do some invasive tests into the structure, in potentially several locations (disturbing your decorations) and you need access to the flat above to survey (affecting that tenant) and you have no right at all to enter their property.

After all this, any report may still be wrong as the building construction details may not be known .... by anyone except the council.

So in requiring all this, it becomes unreasonable to pre-condition approval

You may find that you have been dealing with some unqualified surveyor and been given a standard "council" bureaucratic response.

I would use their complaints system