What considerations do I need to make when converting my garage into a room?

09 July 2018

As most garage conversions fall under the category ‘permitted development’, many of them do not require planning permission. However, it is still important to check permitted development rights in your local area. Before starting work. However, a garage conversion does require a building regulations application. Additionally, this is normally not a requirement for detailed plans. Although sometimes, customers sometimes need more security surrounding the nature of the work, before this commences.

What are the key considerations I need to make when converting my garage?

It is important that the new structure is strong enough to support added weight. Possibly gained from bricking up or adding skins to inside walls. Subsequently, make sure to inspect existing foundations when excavating the door infill.

Walls. Ensure existing walls are stable and free from defects. Specifically, single skinned walls with removed piers will create a weaker structure. And markedly, a new inner leaf will need to be constructed. Along with remedial wall ties.

Weather. It is important your garage conversion is fully weatherproof. A permeable membrane can achieve this. Or a damp course or floor membrane. Cavity wall insulation can also be inserted. Which must overlap with the existing damp course.

house with garage

Insulation. Suitable insulation must be used. As part of this, additional ventilation may be required in the roof. If the building will be lined by stud partitions, they should be fitted tightly. Insulated plasterboard can also be used.

Ventilation. All windows should have a ventilation area 1/20th of the rooms floor space. And trickle vents must also be used (5000m2). If the room can only be accessed via another, a window must provide an escape route (450 x 733 mm)

Sound. Use of appropriate sound insulation is necessary. Usually, blockwork of 200mm in thickness is ok to prevent sound transmission. Anything less than this may require specialist acoustic partitions or more masonry, Speak to your building control surveyor for more information.

Electricity. Electrical installations in your new conversion must comply with the requirements of BS 7671. And also those listed in Part P-Electrical safety in dwellings. If you are unsure of this, speak to your building control surveyor.

house with garage


Most garage conversions don’t require prior planning permission. However, be aware of restrictions on permitted development rights in your local area. And the potential of having to submit a report to building regulations. In this post, we have provided some practical advice for converting your garage to a new room. Including:

Throughout the process of converting a garage, it is imperative to consult a building control surveyor. Find your nearest LABC team here. We also recommend watching this video which covers the conversion of a garage.

Are you considering a new garage conversion?

Contact Phoenix Design Management today and see how we can support you.

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