Short answer: a garage floor usually sits lower than the house floor and often slopes towards the door. In a conversion, the old slab is checked, a damp-proof membrane and insulation are laid, and a screed is laid on top to bring the floor up level with the rest of the house, often with underfloor heating.
Why garage floors need work
- They are typically lower than the house, giving a step at the internal door.
- They often fall towards the garage door for drainage.
- They are uninsulated, and need insulating to meet Building Regulations for a habitable room.
- They may have oil stains or damage that affect bonding or damp-proofing.
The usual build-up
- Clean and check the existing slab, filling any serious damage.
- Lay a damp-proof membrane, lapped and taped, turned up the walls.
- Lay rigid insulation, cut tight, to the thickness needed for the regulations.
- Fit edge strip and a slip membrane, plus underfloor heating pipes if wanted.
- Screed to the finished level, allowing for the floor covering, so it meets the house floor without a step.
Building Regulations
Converting a garage into a habitable room normally needs Building Regulations approval, covering insulation, damp-proofing, ventilation and fire safety. Your builder or building control will confirm the floor insulation required. We work to the specified build-up.
Quick answers
Can I just screed over the garage floor? Not for a habitable room. The floor needs damp-proofing and insulation first.
Liquid or sand and cement? Either. Sand and cement is common for single garages; liquid screed suits larger conversions with underfloor heating.
We screed garage conversions across Billericay, Chelmsford and Essex.
Written by Ben Phillips, director of Chelmsford Floor Screeding Ltd, floor screeding contractors based in Billericay with 20+ years of experience across Essex and London. More about us.