Interior walls on raft foundation

Galsat

Hi,
Does anyone have any idea how find the steel in a raft foundation for the interior walls. Plans have gone missing and need to find the location of the interior walls.
Thanks

Gumbo

Galsat wrote: »

Hi,
Does anyone have any idea how find the steel in a raft foundation for the interior walls. Plans have gone missing and need to find the location of the interior walls.
Thanks

Just ring the engineer that you engaged to design the raft, and ask him to email over a copy. Sorted.

Musketeer4

surely you have a floor plan showing where the walls are to go?

Galsat

kceire wrote: »

Just ring the engineer that you engaged to design the raft, and ask him to email over a copy. Sorted.

Unforunatly dont know who engineer was and persons who put raft in have emigrated. I have the plans but apparantly raft was put in opposite (mirror image)to original plans. Just wondering if there was a way to confirm where interior walls are.

sydthebeat

who told you it was mirrored?

if they know that much maybe they know who the client was and thus who the engineer was?

Gumbo

Galsat wrote: »

Unforunatly dont know who engineer was and persons who put raft in have emigrated. I have the plans but apparantly raft was put in opposite (mirror image)to original plans. Just wondering if there was a way to confirm where interior walls are.

Could be a tough one to figure out. I assume you mean that there are internal walls that will be load bearing and thus, the raft was thickened locally to allow for this?

_Brian

How about a metal detector ??

Musketeer4

^ Don't think that would work as there will be steel in the whole of the raft. Now you might get a higher signal return in the thickened parts as there will be likely be more steel there.

You could try getting on to the likes of -snip/pm poster - surveying if all else fails. They do non-intrusive surveys and may be able to use GPR or some other technique to map the thickness of the raft.

And goodness, how on earth did they manage to build it the wrong way around? If that's the standard of their work I'd worry what other mistakes they've made in the raft.

Gumbo

Musketeer4 wrote: »

^ Don't think that would work as there will be steel in the whole of the raft. Now you might get a higher signal return in the thickened parts as there will be likely be more steel there.

You could try getting on to the likes of -s- surveying if all else fails. They do non-intrusive surveys and may be able to use GPR or some other technique to map the thickness of the raft.

And goodness, how on earth did they manage to build it the wrong way around? If that's the standard of their work I'd worry what other mistakes they've made in the raft.

The problem with those surveys is that thy won't stand over them, and rightly so in my opinion. They certainly would not say "here's where it's thickened" build your load bearing walls in this location.

I think there's more than meets the eye in this thread.

BryanF

Galsat wrote: »

Hi,
Does anyone have any idea how find the steel in a raft foundation for the interior walls. Plans have gone missing and need to find the location of the interior walls.
Thanks

Hi
A small bit of impartial advice,

Get a structural engineer on board now.

If drawings can't be located/trusted, your eng can advise on coring some samples out of the raft, to seek assurance re the rafts strength

You could go timber frame or light weight blocks - there is a solution but, please get professional structural assistance help now.

Ps boards can't offer structural advise, best to read the forum charter.

mickdw

Here is what I would do.
ans from planning department.
Check dimensions to see if they match reasonably.

If there is doubt about the handing of the build, work out a location either side of the house that should find a thickening one end and standard thickness the other and see which way it works out.
Once handing is established, take small cores at important locations that should have thickening and check.
Even having established all that, it's still very much an unknown quantity in terms of steel design, workmanship etc.

Metric Tensor

Hi OP,

Considering the following:
1. The "engineer" who "designed" the raft is missing or never existed.
2. The raft was installed backways - either by accident or on purpose without correct drawings.
3. The people who installed the raft have fled left the country.
4. The raft has presumably been exposed to the environment on top for a number of years.
5. You don't have any proof the quality or strength of concrete that was used i the construction.

Even if you could determine where the beams/ribs of the raft are located would you be confident that the foundation is sufficient or fit for purpose?

Having said all that there are tools and methods to check/examine most of these things, including to find the thickenings, but the methods are expensive and the results have a large error allowance associated with them. If you are determined to use the raft you need to engage an engineer to help you select an appropriate schedule of tests to carry out before going ahead.

A tip - if the engineer seems nervous about taking on the job and covers his backside with multiple provisos and caveats you'll know I'd have more confidence that he understands the situation than one who tells you it's no problem!!

Musketeer4

Is there any ducting or sewer pipes protruding though the raft that could aid in determining the orientation of the slab?

Given the amount of unknowns here the only way you can be sure that you can rely on your foundation is to get the rock breaker in and start from scratch.

Sounds like everyone who was involved in the previous raft was a messer. Built it backwards, ffs.

Galsat

Thanks for the input. Yes there are sewer pipes rising that show where the bathroom etc are but there is no way to confirm where the interior walls should be as the kitchen was supposedly at the back left and was supposedly swithced to back right so dont have much confidence in being sure where the supporting walls should be although the sewer location and water connection for sink would confirm that the plans were changed and are in the correct location if they were. Thanks for the feedback.

Musketeer4

A good structural engineer should be brought in to look at it. Depending on the loading on those walls it might be determined that the slab, even if a wall isn't on a thickened portion, might have enough shear strength to spread the load if the loads are small.
Engineer will have to decide.

Calahonda52

Dig it out and start anew, who knows where the sewer pipes went, are they "handed" as well
Go to the local hire store

http://blogsdir.cms.rrcdn.com/91/files/2015/08/Montabert-V4500-Hydraulic-Breaker.jpg

http://www.silverstatespecialties.com/images/trucks/Dump/Terex3360_01.jpg

Or if you are happy with the drainage, could you add on another reinforced slab on top for about the same mule as all the looking around will cost