Buyer beware rule means home buyers less protected than phone buyer

Section62

AMKin said:

I'm a little confused. Maybe call me naive but pest damage is uninsurable in the UK and rats are a well known and expensive nuisance often coming out of sewers. Why is it OK to have floor voids then when this is a well known problem? 

Building Regs deal with the exclusion of pests, including rodents. They apply in their own way equally to voids as they do to sewers.

There shouldn't be holes or gaps that allow pests into places where they can do damage or live/breed. If there is a need for ventilation then the vent should have a grille and/or screen of the appropriate size. Drains/sewers should have covers on access points, open gullies should have a rodent-proof grating, and vents should be high enough and provided with a screen/grille to stop pests getting in.

In your case it looks from the photos like there is an unfilled gap (between the two extensions) giving access into a floor void. That would be an obvious route for rats to get into space under the floor slab and possibly into the wall cavities from below.

Even without the gap, if the hole on the photos was only filled with what you call 'dirt' then rats could easily burrow through it to get into the void.

Alan2020

Sorry, I don't get it, was this inspect by council building control and signed off?

I don't see anything wrong with this form of construction, maybe soil was pile up afterwards.  How do you think your massive bifolds in the homes have brick work over them? Steel beams not magic.

Pretty standard way to build over sewers etc are you sure you had a full camera survey and dig to see pads?
https://csmanltd.com/project/constructing-steel-beam-foundation-to-crossover-major-sewer/

nnewtoarea

Can you sell it?

anselld

Alan2020 said:

Sorry, I don't get it, was this inspect by council building control and signed off?

I don't see anything wrong with this form of construction, maybe soil was pile up afterwards.  How do you think your massive bifolds in the homes have brick work over them? Steel beams not magic.

Pretty standard way to build over sewers etc are you sure you had a full camera survey and dig to see pads?
https://csmanltd.com/project/constructing-steel-beam-foundation-to-crossover-major-sewer/

Beams should be galvanised if in exposed locations as they appear to be in the CSM picture but not in the OP's case.

Section62

Alan2020 said:

I don't see anything wrong with this form of construction, maybe soil was pile up afterwards.  How do you think your massive bifolds in the homes have brick work over them? Steel beams not magic.

I agree. In principle it would be structurally ok to bridge over a sewer with an adequately designed beam/slab arrangement and then build off that.

However, the problem in the OP's case is in the execution of the work. From the limited evidence we can see, the beams will be exposed to damp and have no protection, the bearing length of the beams on the concrete pad look completely inadequate (about 100mm?), and I would have some doubts about how solid that concrete really is.

Alan2020 said:

are you sure you had a full camera survey and dig to see pads?

That was my question to the OP - just how much investigation work was done before concluding that demolition and rebuild was the only option?

anselld said:

Beams should be galvanised if in exposed locations as they appear to be in the CSM picture but not in the OP's case.

External steelwork, possibly. But if the steel is protected from damp then it shouldn't be necessary. I think those pictures are showing beams with grey primer paint for temporary protection during transport, storage and construction. Unlike the OP's case, it is clear the beams are on proper bearers and there is an air-gap between them and the ground, so once the floor slab is completed they should be in a dry environment. The blurb also mentions encasement in concrete - there is one of the main beams shown clearly encased, but I'm not sure all of them have been.

Encasement in concrete would also give very good protection against corrosion - something the builders of the OP's extension could easily have done without a vast amount of effort.