Ground floor insulation

Ground floor insulation

I’m going to put down new laminate downstairs in a month or so.

Thought I might as well insulate the floor while I’m at it.

It’s a suspended timber floor. Theres about a foot between the joist and ground.

It’s a 70s built house, where there’s air vents from and back, so air can circulate under the floor.

Main goal is to keep cold from seeping up through the floor and the seal off air leaks getting into living space.

Anyone on here know much about insulation?

I was thinking of using rigid board (e.g. Kingspan). Would 60mm do? Held in place with batons on joists, all seams taped with foil tape. Maybe use expanding foam where fitting between the joist and wall.

My concern is if I seal up the air from getting into the living spaces, will I be creating a situation where condensation could happen?

Source: Ground floor insulation