cavity under suspended floor and insulation?

[houstonwehaveaproblem]

Under the suspended floor in our part converted garage is a void about a foot deep. There is a damp proof sheet accross the old garage floor but no insualtion betweeen the joists thus making the room cold. I cant get the floor up and cant get into the void, so whats my options regarding insulation? There is no air brick leading to other parts of the house as the old garage concrete floor is in fact lower than the rest of the house concrete floor. Is it possible to inject some kind of insualtion in the void??

 

[ladylola]

In all truth lifting the floorboards and inserting insulation between the joists would be the only real way, injecting something would be hit and miss at best and really isn't a starter.
Best , and easiest, option is thick carpet and underlay.

 

[houstonwehaveaproblem]

Thanks. At present we have self adhesive floor tiles so that's prob not helping with the cold floor. Perhaps underlay and carpet will improve the heatloss