Floor joists on single storey extension

Hi all,
I have been taking a look at the work done by the builders appointed to build rear single story extension to my house. The length of the extension is around 6.8 meters. We are now 2 weeks down the line and I have been looking at what they are doing with regard to the floor trusses.

I noticed that on my plans that I have a small 'sleeper' wall at the mid point of the single storey extension to the rear (presumably to rest the trusses on). This wall, and indeed the foundations to rest the wall on are absent from what the builders have built thus far. The joists are supported at mid-span from timbers supported directly from the solum (see attached images).

This to me does not seem right and I was wonder if anyone can tell me whether this is OK both from a structural standpoint and what has been agreed from engineers report perspective (to me, any deviation from what is in the plans is a no no)?

If this is a big problem, can anyone tell me an appropriate course of action with regard to resolving this as I have already approached the builders and they stated that "this is the way we do it".

Regards
Colin

we have, in the past, built a stud wall as a mid span bearer. this was built straight off the slab.

we have also built foundations and 100mm block walls to do the same job.

in both cases, the walls supported only ceiling joists and not floor joists.

it was insisted that each upright corresponded with each joist. in our case the joists bore down directly upon the wall header plate, and were not supported off props like yours.

I would have thought that if your builder priced the job based on the plans, including the sleeper wall, you should be due a reduction as what they have done would be at less cost.

Sorry can't help if that solution does the same job as a sleeper wall?

have a look in "your projects" i posted some photos of my single storey extension with a dwarf wall spaning the mid-span of the joists hope you can show the builder what should have been done.

No this is not how to do it.

If the builder will not do the job properley suggest you discuss with the Building Inspector - surely he has not seen this as yet?

That's novel....

And complete cr ap.