When carrying out any significant refurbishment or extension work on a property, it is usually necessary to raise the insulation performance of the walls, floor and roof in that area. In addition to being a regulatory requirement, it also makes good financial sense for owners as it will ensure the space is comfortable and minimise the cost of heating it over time.
In this blog, we’ll discuss the requirements and how the choice of insulation can make a big difference in the final space. To read about how other areas of a garage can be insulated, visit our blogs:
How to Insulate a Garage - Installing on Floors and Walls
How to Insulate a Garage - Preparation
What do the building regulations say about insulating a garage?
To determine how much insulation is needed on the floors, walls and roof, the building regulations set out performance targets for each construction. This is measured in what is known as a ‘U-value’. You can read more about these in our common insulation terminology blog, but to put it simply, they measure how effective the construction is at stopping heat loss. Constructions with lower U-values are more effective at limiting heat loss.
The most suitable U-value for your project will depend on a range of factors such as its design, the materials used to construct it, your budget and the available space inside it. The below values provide a good starting point to ensure the refurbished space is comfortable and meets the building regulation requirements. You can find more detail on the U-value targets for refurbished projects in the guidance documents linked in the table below.
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Flat Roof | 0.15 W/m2K | 0.12 W/m2K | 0.13 W/m2K |
Walls | 0.18 W/m2K | 0.17 W/m2K | 0.18 W/m2K |
Floor | 0.18 W/m2K | 0.15 W/m2K | 0.15 W/m2K |
Table 1 - Typical target U-values for garage conversion
The obvious way to reach a lower U-value is by fitting a greater thickness of insulation, but this could significantly reduce the amount of space within your converted garage. A better option is to fit insulation materials with low thermal conductivities. The lower a material’s U-value, the more effective it is at preventing heat conduction meaning a slimmer thickness can be used. EcoTherm polyisocyanurate (PIR) Insulation boards have relatively low thermal conductivities making them well suited for this application.
To make it easier to work out how thick the insulation needs to be, we have created a free U-value calculator. This tells you which EcoTherm products and thicknesses can be used to achieve your desired U-value. Simply follow the step-by-step process and the calculator will produce a suggested construction.
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.
