How should I fix a hole in floorboards before carpeting?

Hi, Relatively simple fix. Cut 2x 44x20mm battens to the length of the hole and fix them into the existing floor, ensure they protrude along the long edge 20mm. THis will create a ledge for the new infill to sit on. Then cut a piece of ply/MDF or floorboard to the same size as the hole. Try to get materials that is the same thickness as the existing floor. If this is difficult, use closest match and put thin shims to get the correct level. The cut piece should sit onto of the protruding batten edges. Fix the floor to the battens. Use screws and you may need to pilot hole, to stop the boards if using pine from splitting. If you keep an eye on the levels, this will stop the outline of the hole appearing at a later date through the carpet. If the floor is in a bad condition, it may be worth hard boarding the room to smooth it over before underlay/carpet etc. Good luck

Hi Just cut battens to fix to the underneath and have a small off cut of wood to sit on top of the battens and then screw it in

Both previous answers are spot on

Sounds like your describing a vent for a gas fire! First make sure your gas fire is obsolete. Then either make good as the the last advise or just ply the floor first . Depending on your budget a thin sheet of ally or tin to bridge the gap providing it’s not in a walk way would probably be ok. Thanks Simon