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Thinking About A Garage Conversion ??

Updated: May 20

A garage conversion is a perfect way to make use of existing space, but as with any big building project, it does require careful thought and planning. Whether your garage is attached to your property or it’s a standalone structure – if you barely use the space and are in desperate need of extra living / working space, then it is well worth considering a garage conversion. Not only does a garage conversion allow you to make much better use of existing square footage without the need to extend or move, but the conversion work is pretty much self-contained and offers little disruption until it is time to create access into the main property.

A basic conversion of a single garage would normally costs around £8,000 and if the conversion is done well and to a high standard it can add up to 20% onto the value of your home (according to a report by Nationwide) In most cases, you will also be able to convert your garage under your permitted development rights, however it is best to check with your local authority as these may have been removed or there may be some restrictions in your area.

Do I Need Planning Permission for a Garage Conversion?

The answer to this question is ‘Probably not’. While it is best to check with your local authority, integral garage conversions typically fall under something know as ‘Permitted Development’, meaning planning permission is not required. An exception to this will be if you live in a conservation area or the property is a listed building, where you will almost certainly need planning permission.

While permission may not be required it is always advised to check the deeds and home insurance for any planning conditions restrictions attached to the house or garage when constructed (i.e, the garage has to remain as parking) before beginning works as an application will need to be submitted to remove the conditions.

Does a Garage Conversion Need Building Regulations Approval?

There is a very short answer to this one – YES.

You or your builder will need to adhere to the Building Regulations when converting an attached garage into habitable space. The Regs apply to various aspects of the construction, including:

· Fire Safety (Part B)

· Ventilation (Part F)

· Insulation (Part L)

· Electrical (Part P)

A building notice or full plans application will need to be submitted to building control as part of this process. Once received your local building control department will then register the conversion and assign someone to carry out inspections throughout the project, then issue the final certificate on completion.

Before Starting the Project

The first part of any conversion is to understand how the new space is going to be used and what is required within the area. As this can be a tricky thing to visualise some people employ an Architect or an architectural designer to provide design input and ideas that you might not have thought of. A design professional will also have useful trade contacts and will have experience in dealing with Building Control. In terms of design fees, expect to pay anywhere from £1,500 upwards depending on the complexity of the design. Alternatively (and most common) is for people to go it alone and design the layout themselves, and even carrying out most of the work on a DIY basis, which is a good option for those with limited funds and the spare time to get stuck in.

However, the most common option is to find a builder who will have plenty of experience of dealing with any planning issues surrounding garage conversions, as well as building regulations.

Before actually starting any conversion you’ll need to be aware of the various factors that could affect the cost of your garage conversion, including:

· the foundations need reinforcing

· does the garage floors have a small gradient slope which will need to be levelled

· the walls, floors or roof are in dubious condition

· the ceiling height will need to be raised (you need around 2.2-2.4m of headroom once the floor has been raised to 15cm above the external ground level)

· design fees

· planning applications

· the services of a structural engineer.

· Do I Need a Designer for my Garage Conversion?

Assessing the Foundations for a garage conversion is vital as a key part of the project usually involves removing the garage door and partially blocking up the existing opening to fit a new window or entry door. You’ll need to first establish whether the garage foundations were continued beneath this opening and/or the concrete slab is adequate to support the new wall (this normally involves digging a small trial hole). Generally, if the existing concrete slab is 200mm or over, this is generally adequate to extend straight up with new brickwork.

When it comes to additional insulation the conversion needs to address thermal and acoustic factors. Adding external insulation is not usually recommended and most insulation materials are installed internally. A general rule of thumb to use is between 300mm of insulation on any external roof space, 100mm single skin external walls and 100mm for the floor.

As part of the internal finish most garages have a bear brickwork surface which will need to be covered. The simplest method to achieve this is to use insulated plasterboard, fixed to timber battens that are protected by a strip of damp proof course (DPC) placed between batten and wall. Alternatively, insulation can be placed between battens, before a fireproof plasterboard is fixed to them.

For roof insulation, you will only need to look at this if there is no room above the garage already. Two layers of 150mm glass fibre quilt, one between the joists, another over as usual adequate and the space in between flat roof joists can’t be entirely filled. A 50mm air gap must be left above for ventilation.

Garage floors are often lower than the house floor and so adding a damp proof membrane (DPM), insulation and a new screed, along with your final floor covering, is a good way to bring the levels up to that of the rest of your house. When working with very large differences in floor levels, a new suspended timber floor is a good idea. Aim to create a void beneath of at least 150mm between the concrete and underside of the timber, placing insulation between the joists, with new air vents to provide ventilation.

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