Your Guide - Garage Conversion Building Regs







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Thankfully, most garage conversions don't require planning permission which makes it one of the most straightforward and cost efficient ways to add more living space to your home. However, it is likely that you will need approval under the building regulations, so here is our simple guide to garage conversion building regs.

Remember, before carrying out any work, do consult your local authority to check for your specific home and council - this is a guide only.

If you are thinking about a renovation project in the near future and need some help with where to start with your project, try our renovation advice session.

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Why do I need to consider garage conversion building regs?

Since you are converting your garage (or even part of your garage) to a habitable space, you will need to ensure the converted building complies with building regulations, even if you don’t need planning permission. This will include fire safety, drainage, ventilation, electrics, insulation and the overall structure. Building regulations do not supervise the builders work but ensure it meets a minimum standard.

If building regulations aren't followed, you may have to re-do the work or even pay a fine. Not having the correct paperwork when it comes to selling your home will cause complications.

How do I go about getting building regulations approval for a garage conversion?

You can choose to either submit a Full Plan Submission or a Building Notice directly to your council.

Full Plan Submission

This is the most popular and thorough submission and requires a submission of plans. The building inspector will visit the site at various stages of the work and if the work is compliant you will get a completion certificate within 8 weeks of the work being complete.

Expect to pay in the region of £200-£300 for the building regulations application fee and an additional £200-£300 for the building regulations inspection.

Building Notice

This is normally for smaller jobs and the work can start 2 days after the application has been submitted. The planning department will give you 48 hours notice to visit the site and will visit throughout the process. You do not need to submit plans for this process but it does carry more risk as you do not have pre-approved plans to work off.

Expect to pay in the region of £500-£600 for this and must be paid when the notice is submitted to the council.

All fees will vary depending on the local council and the scale of the work, the above is only a guide.

Who submits the plans for building regulations?

If your garage conversion is a large project and you need design ideas, you may want to work with an architect. They will be able to create design drawings as well as prepare the structural drawings for building approval. Your architect will work with a structural engineer who will carry out the calculations for building approval.

For a straightforward garage conversion it is standard to get a structural engineer to complete the scale drawings and they may also submit the plans for you. Expect to pay in the region of £400-£500 for this service. You can submit the application yourself which will take out some of the cost, but you do need scale drawings and calculations from the structural engineer as a minimum if you are submitting a full plan.

So what needs to be done to comply with garage conversion building regs?

Here are the main things that should be considered with regards to a garage conversion, however you will find more detail on the Planning Portal.

Windows and doors

Things to consider include: 

  • All new windows must be double glazed and energy-efficient to comply with building regulations.
  • Ventilation must be considered. Rooms where steam will be produced must have a higher level of ventilation, such as a fan and window.
  • Where the original garage door was, you will need to lay bricks and fit a new window to convert the garage into a room. You will need to check the foundations of the existing garage to ensure that they can cope with the additional weight. The new window and brick work should be in keeping with your original home if you want the space to blend in seamlessly.
  • Make sure your new windows and doors comply with fire safety including having the appropriate means of escape in the event of a fire.

New roof

It might be that your original garage roof is fit for purpose and water tight, but if it’s not you will need to ensure it is fit for purpose. You will need approval if: 

  • You carry out structural alterations
  • The performance of the new covering will be significantly different to that of the existing covering in the event of a fire
  • You are replacing / repairing more than 25% of the roof area, in which case, the roof thermal insulation would normally have to be improved

Insulation and damp proofing

Before you carry out any insulation or damp proofing, you need to check for any water ingress. Checking the original brickwork, pointing, condition of the roof and gutters will highlight any structural issues which could lead cause dampness in the future. Fixing any of these structural issues should be looked at before you look at damp proofing and insulation.

All walls, floor, windows and roof must be insulated to meet building regulation standards as well as damp proofing the walls and floor. Insulation must meet U-values set out by building regulation as a minimum standard, note these are varied within the UK so check with your local authority.

It is advisable to invest in the best possible insulation rather than meeting the minimum standards, particularly if the room is going to be used as a bedroom or lounge.

Electrics and plumbing

The most straightforward way is to use a tradesperson that is authorised under governments Competent Person Scheme. If your tradesperson is registered then they can self-certify that the work complies and, if required, they will tell your local authority of the work on your behalf. They will also provide you with a certificate after completion that is evidence of compliance.

If you are thinking about a renovation project in the near future and need some help with where to start with your project, try our renovation advice session.

Renovation Advice Session

Published: May 19, 2023

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