Has anyone ever had sub floor ventilation ducts installed under their floor?

Dear all,

Any help or advice would be greatly appreciated!

We have inadequate sub floor ventilation which is causing us some problems with damp. The main reason for this is that the newer extension to our property consists of a concrete floor. There are therefore no air bricks at the back of the property allowing air flow through from the air bricks at the front of the house to the back of the house.

We have been told that the best way to rectify this is to use sub floor ventilation ducts which are like long tubes which can run underneath the floor boards from the front to the back of the property. This should allow some air flow to reach the back of the property. We have only found one company that installs these sub floor ventilation ducts so far but their quote was too expensive for us.

Does anyone else know of anyone that could install these ducts for us? This could be a damp company or a general builder perhaps?

Many thanks
Sally