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Building Regulations – UK Planning Permission for Loft Conversions Explained

Building Regulations – UK.

Planning permission is not normally necessary for loft conversions, although this does depend on a number of conditions (for example, there must be no extension higher than the highest part of the roof, no balconies, and there are volume limits too, as well as a number of other factors to consider).

However, building regulations are always part of the process for all loft conversions, whether the conversion needs planning permission or not.

How do loft conversion building regulations work?

Each and every conversion must be inspected for approval, either by your local authority’s Building Control, or by independent, regulated inspectors. No matter who is charged with inspecting your conversion, a ‘building notice’ is required from your local authority before any construction work can begin. Abbey Loft Conversions Ltd will apply for the building notice on your behalf. Once the application is submitted, construction cannot begin until at least 48 hours later.

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Three inspections will be required during the construction of your loft conversion. After the final inspection has taken place and the work has been passed (i.e. your loft conversion meets the building regulations), a completion certificate will be issued. It’s important to keep this somewhere safe so you can prove the safety of your conversion if you ever sell your property.

What do loft conversion building regulations cover?

UK building regulations will cover a number of elements of a loft conversion, including the floor, the structural soundness and the insulation. The regulations are there to ensure that the new structure is completely safe.


Using your loft as a living space will mean that the floor has to hold a lot more weight than it did originally. As such, the structural strength of the new floor of your loft conversion must be sufficient enough to hold the added weight, or it will not meet building regulations. Any joists and load-bearing walls must be strong enough to support the extra weight, and you will also have to install steel beams to support the new joists.

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Fire doors and fire escape

There must be the provision of a safe escape route from your loft conversion in case of fire. Each room of the conversion must have an appropriate escape window, and each window should be easily accessible, with the use of a ladder, from outside. Furthermore, fire alarms should be installed, there must be a self-closing fire door, any new floors and walls must be capable of resisting fire and any glazing used in doors should be fire resistant.

Stairs and access

The stairs to the new floor of the loft conversion must be safely designed. Any staircase to the new living space must be wide enough to allow anyone to use them easily in case of an emergency.

Headroom and ceiling height

Your loft conversion must offer sufficient headroom and a high enough ceiling height for it to be a practical living space. This applies both to the living area itself, and the staircase up to the conversion as well.

Insulation depth, energy efficiency and U-Value

Any dwelling should be energy efficient. Any walls, roof slopes, ceilings and new windows and doors installed in a loft conversion will be measured to determine how much heat passes through the glass and framework. The amount of heat lost must not exceed a certain limit, known as the ‘U-Value’. Even if the rest of your existing property doesn’t comply with this standard, your new loft conversion still must have sufficient insulation to meet the building regulations.

In terms of keeping sound transference to a minimum, insulation between the conversion and the rooms below must be sufficiently effective, as must the insulation in any new internal walls. If you live in a terraced or semi-detached house, you may also find that you have to improve the insulation between yours and your neighbours’ lofts.


Your new loft conversion must be ventilated properly to ensure that it meets building regulations. There should be a window that is a twentieth of the total floor area of the new living space, and there should be a mechanical fan of sufficient power if you are installing a bathroom. The roof void must also be ventilated to prevent condensation.

The information provided about loft conversions and building regulations above is designed as a brief guide to get you started thinking about what you might need to do to comply and get your conversion passed. However, each conversion will be judged individually. If you have any questions about loft conversions and building regulations in your area, you should call your local authority. Abbey Lofts will be able to provide further advice also.