Hardboard on joists?

Hi Guys,

We're having a new extension built and the builders have got to the flooring stage. They have laid hardboard sheets down over the wooden joists to form a floor. Is this normal instead of floor boards?

We're just a bit worried in case we should query this with them.

Thanks for any help you can give.

All the best
Chris

 

One of the lads put an answer on the 1st post you made asking this question