What are the Loft Conversion Building Regulations, How to Get Building Regulations Approval




woman looking confused at building regulations for loft conversions

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Has the bloke down the pub told you that you don’t need to worry about the building regulations when you convert your loft? As usual he’s wrong and got everything backward. You must comply with the building regs when you convert your loft. And if the know-all in the bar starts muttering about permitted development tell him he’s a complete plonker. It’s nothing to do with permitted development and all about building regulations approval.

When you convert the loft into a liveable space you must apply for building regulations approval. There are no exceptions here. You must comply with the building regs when you make structural alterations to your home.

If you don’t obtain building regulations approval for your project your loft conversion will be illegal and could cost you a fortune in putting things right. Your home insurance will also be invalid, and you may even fall foul of your mortgage provider.

The loft conversion building regulations can seem a little intimidating but are to a large degree common sense and are there to protect the homeowner as much as anything.

The building regs include guidelines on the standards to which the loft conversion must be built and how it complies with fire regulations, structural stability, sound insulation, and energy efficiency.

Why you need building regulations approval

Quite simply the loft was never intended to be a liveable space. The existing timber joists aren’t strong enough to support a new floor, there is no access, no insulation, the roof structure may not be suitable, and finally there is no safe egress in event of fire.

Fixing all of that to make habitable rooms involves major work which must be done correctly or the property will become dangerous. To ensure the loft conversion is safe and built to standard, the work must comply with the building regulations and the homeowner must make a building regulations application to their local building control office.

Your loft conversion and the building regs

It may seem like an annoyance and a headache but don’t get wound up about the building regs. As I mentioned above, they are as much about your protection as anything else.

But there is one thing you must accept before you begin planning or building your new loft conversion. There are no shortcuts and you MUST comply with the building regulations. If you don’t you will find yourself in all kinds of hot water and your conversion will be illegal. You can apply to your local authority or any approved inspector for building control approval.

Why do we have building regs for loft conversions?

Adding extra space to your home with a loft conversion is a great idea. Utilising the loft space of an existing house can save the expense of moving and add even more value to your home. But as with any good idea there are hoops to jump through in the form of red tape but in the case of converting your loft this is entirely justified.

Without building regulations it would be a wild west and cowboy builders would have a field day with dodgy and unsafe work. The building regs ensure every loft conversion is done correctly and to minimum standards ensuring the safety of the homeowner and the integrity of the building.

When undertaking a new project the building regulations, as you would probably expect, are very in-depth and dense – but not to worry because here we boil everything down to the basics.

What follows applies to the current legislation in England and Wales and to a large degree Northern Ireland. But it should be noted that the building regs are different in Scotland.

Unless you are installing a basic storage solution by laying chipboard flooring you must have building regulations approval for your project.

At this point it should be noted that the building regulations are not the same as planning permission. In most cases you will not require planning permission for your loft conversion but, it bears repeating, you must comply with the building regulations. What follows applies to two storey houses and buildings.

Ok, so what are the building regulations for loft conversions?

The building regs are the minimum allowed standards of construction and design as laid down by the government and, for loft conversions, they fall into a few main categories:

Structural changes

For anything other than light solutions you will need to install new ceiling joists and will more than likely have to double them up. The existing timber joists are just not strong enough.

That new liveable space in the loft is going to have to carry some serious weight and the loft conversion building regulations insist that joists and load-bearing walls are strong enough to support that extra weight.

It’s likely that you will also have to install new steel beams to support those new floor joists.

Another facet to structural stability is the roof itself and whether its structure and roof trusses needs to be altered to fit in your new conversion. All builders will employ or consult a structural engineer before they begin the job of converting your loft and the roof type will play a big part in their plans.

Fire Safety

It goes without saying that the loft conversion building regulations on this point are very strict and rightly so.

The plans for your conversion must give plenty of consideration to fire safety and your design will need to take into account the new rules on fire doors.

Your new loft floors and walls must be able to resist fire for thirty minutes and glazed door panels must be made of fire-resisting glass.

Escape from the loft in the event of a fire must be addressed with a full escape route provided by a protected stairway. It should be noted that escape windows in the loft are no longer acceptable except for certain bungalow conversions.

Mains operated smoke alarms, linked to others in the property, must also be installed.

Ventilation and windows

New loft conversions need rapid and background ventilation. Rapid ventilation simply means a window which is equivalent to 1/20th of the floor area.

If you are converting your loft to a bathroom then mechanical ventilation is also required which needs to extract 15 litres per second.

In addition the new roof space needs to be ventilated to prevent condensation and you may also need to ventilate at the eaves level and ridge.

There must also be a minimum air space of 50mm between the roof covering and the insulation though this may not be necessary in older houses with no roofing felt.

Finally, windows (usually Velux windows) must be big enough to provide an escape route should a fire break out. You’ll also want large windows to let in plenty of natural light, especially if you’re having dormer windows fitted.


The new stairs are probably the most important element, in both an aesthetic and practical sense, of your new loft conversion project.

Getting the new staircase and access right will have a massive bearing on the success of your project but the loft conversion building regulations throw up a number of things that you will need to consider when planning your staircase to the loft.

The important point to get across here is that the new loft stairs must be permanent. In other words you must install a fixed staircase. A ladder just won’t cut the mustard.

Because of the importance of the staircase to your loft conversion there really is no quick way to sum up the relevant information so take a deep breath, fill up the whiskey glass, get the wife/husband/partner to massage your back and click here for a detailed discussion.


Again you don’t really need to be told that this is important and why would anyone go to the trouble and expense of converting their loft and then not insulate it?

Nevertheless the loft conversion building regulations insist that your loft, including new internal walls, must have good quality insulation.

But the building regs are more concerned about sound insulation. The new loft room must be insulated to prevent excessive noise in other parts of the house.

Interestingly one thing the building regs don’t worry too much about is head height. But naturally enough you need to be able to stand up straight so how high the ceiling of the rooms are is important. It’s just not laid down in the regs. Anyway, I’ve digressed. Back to the topic in hand.

Building regulations approval

As we have stressed throughout this page, obtaining approval for your conversion project is an essential step to ensure your project meets health, safety and design standards.

The application should be made before work begins and there are two main options for the application, either making a full plans application or by giving a building notice.

A possible third option is to use an independent inspector.

Full plans application

The recommended route. You need to submit copies of your plans showing construction details along with a completed building regs application form.

You will also, of course, have to include a fee with your application. This is a necessary evil which must be tolerated (a bit like the mother-in-law). Fees may vary but you’re probably looking at a few hundred quid.

Once the council have received your loft conversion plans their building control officers will check that they meet the building regs and will then issue a notice of approval.

If there is a problem the building control officer will ask you to submit revised plans before approval is granted.

Once you have your notice of approval, work on that brand new loft conversion can begin.

The building control inspector will make regular visits to ensure that the work is carried out in line with your approved plans and loft conversion building regulations application.

Building notice

Easier than making a full plans application but going down this route could lead to problems later on down the road.

This kind of application doesn’t require any plans to be submitted, just an application form and a fee (same charge as for the full plans application) – basically all you are doing here is telling the council that you will be carrying out work on your loft conversion and that you will comply with the loft conversion building regulations.

The building control officers can ask for detailed plans if they wish but that is unusual.

By giving building notice no actual approval is issued by the council so there is more onus on you to ensure that the building regulations are met. Site inspections will, of course, still be carried out.

A very important point to note is that under the building notice procedure the local council are not obliged to, in other words they won’t, issue a completion certificate.

As we said earlier, you can choose to go private if you don’t want to deal with the council’s building control surveyor. You can apply to a private approved inspector who will then give initial notice to the council. Sometimes your builder will recommend this route if they have a professional relationship with a private building inspector.

Ready to submit that application?

Unless you know the loft conversion building regulations inside out make a full building regulations application. And even if you do know the building regs backwards – it may still be best to submit your full plans. The council’s building control officer is in affect your quality control expert.

He will ensure your plans are up to scratch and will also inspect your work, or that of your builders, for you. This site inspection can help prevent all sorts of problems.

Another point in favour of making a full plans application is that if you enter a dispute with the council i.e., disagree with their decision you can ask for a ‘determination’ from the Office of the Deputy Prime Minister or Welsh Assembly to settle the dispute – this service is not available if you simply give building notice.

How long will it take to get my approval?

The government guidelines issued by the Office of the Deputy Prime Minister, state that the local council must give you “a decision within five weeks or, if you agree, a maximum of two months from the date of deposit.”

Of course, if the council believes your application doesn’t satisfy the building regulations, then they will reject your application and will not grant approval.

So when can I start work?

If you have taken the time and trouble to make a full plans application it is best to wait until you have received your notice of approval.

But, if you wish, you could begin work by notifying the council at least two days in advance once you have made your application.

Not to be recommended if you think there may be a problem in satisfying the building regulations.

Under the building notice procedure you can begin work after two days as there are no plans to consider.

When your loft conversion is finished

When your loft conversion is finished, the staircase is in place, the new loft windows fitted, and the fire precautions satisfied and the council are happy that the work meets all the building regulations they will issue you with a certificate of completion.

Make sure that this certificate is kept with the original approval notice as these pieces of paper will be vital when it comes to selling your property. They are your record that your loft conversion has been built well and in accordance with the building regulations.

Important tip

You must state in your initial application that you want a final completion certificate when the work is finished. Sounds ludicrous but don’t forget.

Other regs to consider

You’ll need to think about planning permission (especially if you’re in a conservation area) and, if you’re in a terrace or semi-detached house, a party wall agreement. We cover these in depth elsewhere on the site but planning permission shouldn’t be confused with the building regs and the Party Wall Act isn’t anything to worry about.

A word about the council

Let’s be fair, local government often get a bad rap. Council officers are seen (sometimes justifiably) as jobsworths. But I have to say that every time I’ve dealt with the local building control body, they have been very helpful. And are always willing to give further advice when needed.

Don’t see the building regs or the local authority inspector as hurdles. They are there to ensure your specific project proceeds to plan and is above all completely safely and to the best standard.

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