Obtaining previous Building Regs info for property

I'm looking to purchase a property which I want to make some structural modifications to.
To do this work I (obviously) need to get a structural engineer to check that this new load I am introducing can be supported by the current construction.
As the property was a fairly recent conversion, is it
a) possible to get the complete technical description of the original build from my local BCO?
b) allowed to use the fact that this build was checked by the BI to assume that the building does actually meet the stated spec or is it still necessary to "open up" the build to check?
And in case you are confused by my asking this, the building is built on a, presumably reinforced, concrete raft not directly on foundations built into to the ground. Obviously this raft is supported by foundations, but I can't change those nor do I think that I'll be allowed by the owner of the rest of the building to "open up" this raft, so will be somewhat stuck if this is necessary.
TIA
tim
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"tim...." wrote

For part a), ISTR going to building control and requesting drawings of changes to a near(ish) neighbour's property. Solely out of interest in what was proposed (and whether it would be worth giving our place the same treatment). They charged some exorbitant fee for a copy.
Phil
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tim.... wrote:

Should be.

Nice point. Depends whether you want a legal or an engineering solution really.

That is not leagal within the last 20 years or so ..unless its on bedrock.

Ah. so there are strip foundations as well..Underpinning inadequate foundations is not as impossible nor as expensive as people think.
About £1000 a linear meter roughly.
If your modifications include adding more structural weight, the BCO would probably insist that someone does dig down, and upgrade if necessary. That's where a structural engineer comes in handy.
Now regs in foundations are hugely increased vis a vis what they were say 20 years ago.
I'm shooting from the hip here, but if I were a BCO and someone was say doubling up a building by adding another storey, I would probably insist on either new foundations being dug.. or underpinning, if there was any doubt. Again a call to a firm of structural engineers costs little or nothing, and may save thousands if you start the wrong way and have to do remedial work.
I cant see the owner of the rest of the building minding if you improve his half at your expense, either.
I would suggest a free frank and honest chat with the BCO and with some structural engineers and an architect and the owner of the other bit, to cost out what you want. If the conversation outcomes look expensive or impossible, walk away.
In the limit, also cost out complete demolition and rebuild. Sometimes its cheaper and more predictable cost wise, and should set an upper limit on the project costs at least.

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to further clarify, the raft sits above the communal parking area for 10-12 cars.

I want to add an internal floor to a room that currently has a single storey with a very high ceiling into the open roof space.
It's meant to look pretty (which it does) but is a great waste of space (not to mention likely to be difficult to heat).
I'm not sure but I suspect that in addition to the weight of the new floor I will also have to add structural weight to the internal walls that the new joists will abut from. It's this extra weight that's likely to be the killer.
(and before anybody asks, part of the building already has a second floor into this roof space so I do know that it's high enough)

One side of this wall is inside the adjacent property. The other side is the floor of the parking area. I very much doubt that I will be allowed to dig up either (let alone under pin it)

Managers of communal areas are very conservative in what they will allow. Saying "no" is never a risk of being wrong.

I know. But I'm not going to get all the answers before I must decide so I want to know what the parameters are.
Visiting the local BCO and getting some calcs based upon the documentation is as far as I'm going to get.

Not an option (but I suspect that you see this now)
thanks
tim
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On Wed, 11 Nov 2009 18:19:47 -0000, "tim...."

The real killer will be the imposed load on the new floor that the structure will be required to be designed for. It isn't just about the weight of the floor.
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[Default] On Wed, 11 Nov 2009 18:19:47 -0000, a certain chimpanzee,
wrote:

Ah! You mean a suspended slab. A raft is a type of foundation bearing onto the ground.

The vast majority of the mezzanine floors I see are supported off the main loadbearing walls, usually the external walls, party walls and sometimes internal walls. The extra weight of an internal floor is fairly inconsequential compared to the dead weight of the rest of the building and the imposed external loads. However suspended slabs are usually just designed just to take the loads imposed on them at the design stage and no more.
You say it's a conversion. From what to what? How old is the building? The replies so far have been just stabs in the dark. A little more light is needed.
--
Hugo Nebula
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randomly hit the keyboard and

Sorry. I got the terminology from the redevelopment of railways station. When they build shops etc over the tracks they always describe this (to normal people) as "building on a raft".

The property is built on one half side of the slab from front to back, there is a second property on the other half of the slab so there is a party wall down the centre of the slab from front to back. The outside side walls of the property are shared with other parts of the complex.
The new floor will run from the party wall to an internal wall and will thus be over the centre of the "slab". This internal wall is made up from one of the original building's wooden beams which has obviously been strengthened by the use of extra steel items. Under this beam is a stud wall. Currently this beam is used to support the joists (and stud wall) of the existing half upper floor which runs from the internal wall to the outside side wall. If I am to place extra stress on this bean by building the missing half of the second floor level I suspect that I will need to replace the stud wall with a solid wall to take the load directly down to the slab rather than along the beam and down to the ground via the external wall. (Does that all make sense). It's the effect/weitht of this new wall that bothers me.
BTW it's not possible to put the new joist in front to back.

A victorian factory. Apart from this "pretty" internal wall it difficult to find anything original.
The new build is complex of apartments with the new stuff built from brick

Original, no idea. New build from 2001.

Realistically I don't expect to find out on a news group if "it can be done", I just wanted to find out what the process was.
But if you think you can tell me if it can be done, feel free to try.
(I'm going to see it again tomorrow so I'll have a better idea how the slab is constructed)
Thanks
tim
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[Default] On Wed, 11 Nov 2009 16:16:14 -0000, a certain chimpanzee,
wrote:

Firstly, never assume that all properties HAVE a valid application. There are plenty of unauthorised conversions, extensions and even new-builds around.
Secondly, if it had a Building Regulations application, it may not have been with the local authority. It could have been an Approved Inspector.
Thirdly, even with a valid application, it may not have had plans, but been a Building Notice (with the LA). Even if there were plans, they may not have been approved. AIs don't necessarily require plans, and very rarely issue plans certificates (approved plans).
Fourthly, it may not have been inspected.
Fifthly, BCOs aren't structural engineers. They have experience in a broad range of structural matters to a greater or lesser degree, and if there were plans available they may well have been checked against the reinforcement on site, but that's by no means a certainty.
Sixthly, it may not have been completed, or may have outstanding items (including structural ones).
Even if all the above go 'in your favour', the LA shouldn't let you have sight of the plans and calculations without the current owner's permission (Building Regulations applications aren't public documents like Planning). You won't be able to take copies of the plans without the original architect's or engineer's permission (it's copyrighted material).
When you say the building is on a raft rather than foundations, a raft is a type of foundation.
--
Hugo Nebula
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I thought you generally had sight of the drawings, but the drawings are copyright of the architect., unless rights have been assigned to the owner, which is unlikely!
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I don't need the drawings for their own sake. I just need to know the structural characteristics of the suspended slab.
tim
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On 12 Nov, 23:04, "tim...." wrote:

The planning application will have the agent's (usually the architect or main contractor) details - they might let you have details of the construction or be able to give you details of the structural engineer who handled the design.
That structural engineer might be happier to use estimatory techniques as he knows the building.
Owain
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randomly hit the keyboard and

It's a complex of 20 properties so I doubt this applies.

I found this out today at my current LA's (where I rent) BCO.

Hm, never considered this possibility

It looks complete :-(
Thanks
tim
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[Default] On Thu, 12 Nov 2009 22:36:19 -0000, a certain chimpanzee,
wrote:

I have on my desk a conversion of a nursing home to 10 flats. An application was received in 2003, and the plans were rejected as (amongst other things) having an inadequate means of escape in case of fire. The building was converted and has been lived in for over five years, but only now has it come to light that no inspections were carried out, and there could be major work needed to make it comply.
A few years ago, I was involved in the Regularisation of a block of 21 flats that had got to roof height before anyone noticed it was there. I know of bigger sites than that without applications.
Don't even begin to imagine that building work is regulated in this country. Parts of our towns and cities are beginning to resemble favelas.
--
Hugo Nebula
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