How to ensure the garage is properly ventilated
As the ultimate goal of your garage conversion is to create a warm and comfortable space, the changes you make will almost certainly reduce air-leakage. To ensure a supply of clean air, and avoid any issues with condensation, the Building Regulations and Standards therefore require ventilation to be introduced as part of any garage conversion.
If the room is just being used as a home office or children’s room then this can typically be achieved by adding a window which can be opened and has a trickle vent at the top or bottom to allow some constant air flow. If you are adding a shower or intending to use the space as a workshop then it is likely that an extractor fan will need to be fitted that meets the regulatory requirements for the particular building use.