Ridge in floor over steel

[tag338]

Hi,

I live in a new build (never again) and the floors in one of our bedrooms has quite a pronounced ridge running across the room. To give you an idea of the size, if I balance a 900mm spirit level in the middle there is about 8-10mm between the level and the floor on both sides.
The builder says there is a steel under the floor running in line with the ridge but also says the joists run 90 degrees to the ridge.

I am pretty confused how this has occurred as I had originally thought the builder just made a bad job of levelling all the joists but this doesn't seem to add up if they are running the other way!

Having pulled up the carpet the top of the ridge runs along where two boards meet so maybe compression? It feels very firm tho and doesn't give at all.

I have raised this with the builder more times than I can count and am rapidly running out of faith they will fix it to an acceptable standard.
I am trying to understand what has happened so I can make an informed decision going forward.

Does any of this make sense to anyone?

I have attached a diagram to help illustrate what I am talking about. Obviously the steel wouldn't be running through the joists but it gives an idea of what the builder has said is within the floor.

Any insight will be greatly received!

 

[dazlight]

The problem these days is most new builds are rushed and corners cut. Most of the trades are on a price now so rush to get things done.
You could 9mm plywood the room but leave it 400mm short of of the ridge then use a fibre screeding compound to over the ridge to make the room level.

 

[JohnD]

I've got something similar. Currently the floor is shimmed to spread the hump along about 1200mm on each side, but after more thought, I think it would be better to groove out the board with a router or something where it touches the steel. This would weaken it so I think it will need some sort of additional support from extra nogs or something.

 

[bobasd]

if the steel or anythin else is the cause of your problem then its a case of findin out why.
youve got to get the builders back on the job - dont you mess with it.
first talk to your conveyance solicitor.
read the similar threads in the Planning and Regs forum.