19 July 2023 · Sharon Winson
How to insulate a prefab garage
An internal timber frame with insulation between the studs is the proven way to make a prefab concrete garage warm, dry and quiet.
The most effective way to insulate a prefab concrete garage is to build a light timber frame against the inside of the walls, fit insulation between the studs, and finish with plasterboard or plywood. Done properly, it cuts heat loss, keeps condensation under control, and turns a cold garage into a comfortable year-round space.
What is the best way to insulate a prefab garage?
Insulate from the inside with a timber stud frame. The studs fix along the walls and roof, insulation such as fibreglass or mineral wool sits between them, and a plasterboard or plywood lining goes over the top. Include a vapour barrier so moisture can't get into the insulation and lose you the benefit.
This approach suits sectional concrete buildings because you never touch the structure itself — the concrete panels keep doing their job of holding the weather out, while the new lining handles warmth on the inside. A single-skin concrete panel on its own conducts heat, so the insulated frame is what makes the real difference.
Why insulate from the inside rather than the outside?
Internal insulation is simpler, cheaper and doesn't change how the building looks from the garden. Timber studs are easy to position wherever you need them, the lining gives you a clean surface you can paint, and you gain somewhere to run cables and mount shelves, benches or tool boards.
You do give up a little floor space — the frame and lining typically take a few centimetres off each wall — but on most garages that's a small price for a room you can actually use in January.
Does insulating a garage stop condensation?
It helps a great deal. Condensation forms when warm, moist air meets a cold surface — and bare concrete in winter is exactly that. An insulated lining keeps the surfaces you see and touch much closer to the air temperature, so there's far less for moisture to condense on. The vapour barrier stops damp air reaching the cold side of the wall.
Insulation works best alongside decent ventilation and a dry base, so it's worth understanding where garage damp comes from before you start.
Does insulation make a garage quieter?
Yes. Mineral wool in particular absorbs sound as well as holding heat, so an insulated and lined garage is noticeably quieter — both for keeping workshop noise in and traffic noise out. If you're planning a music room, home gym or workshop with power tools, that's a genuine bonus on top of the warmth.
Related reading: do concrete garages get damp? covers ventilation and moisture in detail, and how to insulate a concrete garage floor completes the job underfoot. Starting from scratch? Browse our concrete garage ranges first.
Can I insulate a prefab garage myself?
Yes — a timber frame, insulation and plasterboard lining is a realistic DIY project for a competent home improver. Take your time getting the vapour barrier right, as that's what keeps the insulation dry and working.
How much space does internal insulation take up?
The stud frame, insulation and lining typically take a few centimetres off each wall. On most garages you'll barely notice the difference once the walls are boarded and painted.
Should I insulate the roof as well as the walls?
Yes — heat rises, so an uninsulated roof undoes much of the good work in the walls. The same stud-and-insulation approach works on the roof, and it also cuts condensation dripping from cold roof sheets.
What about the garage door?
The door is usually the last cold spot. Insulated door kits and draught seals help, or if you're using the garage as a workshop rather than for a car, some owners replace the up-and-over door with an insulated wall and a personnel door.
Do Nucrete garages come insulated?
Our buildings are supplied as standard sectional concrete garages, which most customers insulate afterwards if they want a heated space. Ask us before you order — we've helped customers plan insulated workshops for years and can advise on the best starting spec.