Budget 2020: Chancellor Announces Affordable Homes Pledge, but Industry Experts Left Disappointed

Chancellor Rishi Sunak has delivered his first Budget and there is disappointment that, despite prominent campaigning from industry experts, there have been no tweaks to VAT to support the renovating of existing homes.

Prior to the Budget, house builders and industry leaders had called for VAT cuts on home repair and renovation, which the Federation of Master Builders (FMB) said would help to boost economic growth and reduce costs for those renovating a house. 

In data released earlier this week, the FMB revealed that 212 out of 357 small to medium-sized building companies supported VAT cuts.

Responding to the Budget, Brian Berry, chief executive of the FMB said, “The Chancellor has missed an important opportunity to announce interventions that would support the sustainable, long-term recovery construction needs.”

“The autumn Budget must include measures to cut VAT on repair and renovation, and a National Retrofit Strategy to promote decarbonisation and create jobs and growth.” 

Hew Edgar, head of RICS UK Government Relations & City Strategy, added: “We’re disappointed the Chancellor didn’t support the property industry to retrofit thousands of buildings, turning them into places people would have loved to call home.”

Chancellor Makes Homebuilding Pledge

One of Mr Sunak’s standout announcements was to pledge an extra £9.5bn, totalling £12bn, for the Affordable Homes Program from 2021-22. This will be used to build 70,000 new homes in areas of need. Mr Sunak described it as the biggest cash injection in affordable housing in a decade.

The Budget also re-emphasised the government’s commitment to build at least one million new homes by the end of the Parliament, and an average of 300,000 homes a year by the mid-2020s.

“Today I can make good our promise to extend the Affordable Homes Programme with a new, multi-year settlement of £12bn,” the chancellor said.

The news was positively received by Tom Slingsby, chief executive of property developer Southern Grove. He said: “This cash boost for affordable homes will underpin building for many years to come and is a declaration of war on a housing crisis that isn’t going away.

“Only sufficient provision of affordable homes in the right areas can prevent the sort of social inconsistencies that appear when high property prices put key areas of UK cities off limits to younger workers and their families.”

Despite the investment, Berry reflected that a lack of additional support for small and medium-sized (SME) homebuilders could jeopardise this target.

“Master Builders are facing major barriers finding land, accessing finance and skilled workers – these will all need addressing if we are to build 300,000 homes a year,” said Berry.

Planning System Overhaul

The chancellor also promised to overhaul the planning system, with housing secretary Robert Jenrick expected to announce reforms on Thursday.

The proposed reforms will bring the planning system “into the 21st century”, according to Mr Sunak, which will be followed by a planning white paper later this year.

No Reference to Self Build

While the Conservative Party’s General Election manifesto directly referenced self build, promising to help first-time self builders access the Help to Buy scheme using 5% deposit mortgages, this pledge has yet to be fleshed out.

And today’s Budget leaves us with no extra information. While the initial reference to self build last December was considered significant for the sector, there is no elaboration of this pledge or how it will be rolled out.

However, Andrew Baddeley-Chappell, chief executive of the National Custom and Self Build Association (NaCSBA), says that while the Budget negates self builders, it is not all doom and gloom.

Baddeley-Chappell told Homebuilding & Renovating: “Overall it is always nice to hear your sector referenced, but no news does not mean bad news. There is nothing to complain about for us in this budget so it is a really a case of wait and see – with the promise of more to make it easier to build that we hope we will be a bigger part of.”

The disruption caused by coronavirus is reportedly spreading into the construction industry, but self builders have been advised to carry on as normal.

The coronavirus disease COVID-19 has, at the time of writing, led to three deaths in the UK. Prime Minister Boris Johnson is today chairing an emergency Cobra meet to assess whether measures need to be implemented to delay its spread.

While the extent of the threat remains speculative, concerns have been raised about large groups of people in close proximity, and this may yet apply to construction teams working on developer sites.

“The potential impact on the construction industry is clear,” said Ian Atkindon, partner, and Michelle Essen, managing associate at law firm Womble Bond Dickinson. “There would be delays on site, there would be risks to a workforce that often finds itself working in close contact with each other and the questions are already being asked about who would bear the costs and risks of delay.”

Could Self Builders Be Affected?

There is potential for self build project timelines and costs to be affected if builders are not able to arrive on time, or unable to transport required materials. But Andy Stevens, builder and consultant with Eclipse Property Consultants, is optimistic that fears for the construction industry may be overblown.

Stevens told Homebuilding & Renovating: “Every builder that I know is just carrying on as normal. My advice to any self builder or renovator would be: carry on as normal. This shouldn’t stop anybody in the construction industry doing their job. 

“If anything, we’re in a better position because we’re outdoors, or areas with doors and windows open, so we have air flow. We’re handling blocks, timber, sand, plaster; we’re not handling stuff that someone may have sneezed on, or touched, so I think it’s one of the safer industries to work in.”

Coronavirus Impact on House Prices

While UK house prices neared in all-time high in February, mortgage lender Halifax has warned that the potential impact of coronavirus could spread to the property market later in the year.

Russell Galley, Halifax managing director, said: “The UK housing market has remained steady heading into early spring. The sustained level of buyer and seller activity is strong compared to recent years, with positive employment conditions and a competitive mortgage market continuing to support demand.

“But, looking ahead, there are a number of risks, including the potential impact of coronavirus, which continue to exert pressure on the economy and we wait to see how these will affect housing market sentiment later in the year.”

This beginner’s guide to building an extension covers everything you need to know before you start. From what to design to getting plans passed, from working out your budget to the trades and build – it pays to know what building an extension involves.

After all, you’ll be investing financially and emotionally in building an extension so you want the build to go as smoothly as it can do! So let us guide you through the things you need to know.

How Much Will Building an Extension Cost?

Depending where you are in the UK, for a straightforward extension you should allow around £1,000–£2,000/m². But, the cost of your extension will all come down to a number of factors, including size, specification and location.

Building a single-storey extension will cost the following per/m²:

• Basic quality: £1,000 to £1,680
• Good quality: £1,680 to £1,920
• Excellent quality: £1,920 to £2,160

Building a two-storey extension will not cost much more per square metre because, aside from the extra interior fixtures and finishes, you are only adding walls and floor joists — a roof and foundations are required whether your extension is single or two storey.

What Should I Consider Before Building an Extension?

Any Shared Walls

If building your extension involves digging or building foundations within 3m of the boundary, party wall or party wall structure, or digging foundations within 6m of a boundary, the work will require you to comply with the Party Wall Act.

Site Access

How easy will it be for deliveries to be made to your home when building an extension? You’ll need to factor in how trucks and lorries will reach the property and unload large items and materials. You’ll also need to determine where trades will park and store their tools.

Demands on Your Services

Don’t forget to give your current services a health check. Don’t assume that your electrics, heating and plumbing will be able to cope with lighting and heating extra space. For example, while replacing the boiler is an option, you could also look at alternatives such as underfloor heating.

Don’t Forget

Other important aspects to consider before you get to the stage of getting your plans drawn are matters like:

• soil conditions on the site
• services
• surrounding trees
• any history of flooding
• rights of way.

Insurance

Importantly, notify your insurer of the work. Some may not provide cover during the works, but others offer dedicated extension insurance products.

Do I Need Planning Permission When Building an Extension?

Not necessarily. In many cases you will be able to build an extension under Permitted Development (PD). These rights allow certain works to be carried out to your home providing you meet the criteria.

Under PD, the following rules apply:

• You can extend a detached property by 8m to the rear if it’s a single-storey extension, or by 3m if it’s double
• A single-storey extension can’t be higher than 4m on the ridge and the eaves, and ridge heights of any extension can’t be higher than the existing property
• Two-storey extensions must not be closer than 7m to the rear boundary
• Side extensions can only be single storey with a maximum height of 4m and a width no more than half of the original building
• Any new extension must be built in the same or similar material to the existing dwelling
• Extensions must not go forward of the building line of the original dwelling
• In designated areas (such as areas of outstanding natural beauty, conservation areas, etc), side extensions require planning permission and all rear extensions must be single storey
• An extension must not result in more than half the garden being covered

You should bear in mind that if your house is in a Conservation Area or a National Park, the amount of work under Permitted Development is usually reduced.

If you’re planning a significant extension you’ll likely need planning permission and will need to submit an application. Engaging with your local authority early on and researching local planning policies to know what’s likely to get approved is a good idea.

You can either apply for consent via the Planning Portal or through your local authority. An application in England for an extension currently costs £206.

Building Regulations for Building an Extension

Whether you require planning consent or not, you will need to make sure you comply with Building Regulations. To meet the Regs, you can either submit a Full Plan Submission or a Building Notice.

• Full Plan Submission: send plans to your local authority building control or approved inspector prior to the build for approval. The building inspector visits your site at different stages and inspects the work as it progresses
• Building Notice: a statement which lets the local authority know that you will be complying with the regulations in building your extension and gives the building control department 48-hours notice of your intention to start the work. Building inspectors will inspect the work at various stages and will advise you of any problems

A Building Notice is the riskier of the two as you may only find out you have a compliance issue once building work has started, which then needs to be paid to be put right.

Listed Buildings

All alterations to listed buildings, including internal ones, require consent and it is a criminal offence to alter a listed building without it.

With a listed building the planners will always regard the existing property as more important than what you are proposing to add to it. Any extension will therefore have to respect the flavour, appearance and historic material used in the construction of the original house.

Warranties

Getting a warranty for your extension is advisable as it will cover you for things such as structural defects or faulty workmanship. Should the worst happen, the builders who did the work will need to return to put right what has gone wrong.

How to Design an Extension

One of the first things you’ll need to think about is who is going to design your new extension. You can choose to design it yourself, opt for a build and design company, or you can work with an architect or architectural technologist.

(MORE: 20 Extension Design Ideas)

Finding an Architect or Designer

Choosing the right person to draw up your plans is as important as choosing the right builder, and the prospect can be just as daunting.

The key is to do your research, look at previous work and ideally speak to past clients, and choose someone who most closely aligns with your design aspirations, and who you feel you can work with best.

Bear in mind, if you’ve designed the extension yourself you may need the aid of a designer or draftsperson to draw up your plans to submit them for planning approval (if required) and a structural engineer to produce drawings and calculations for Building Regs’ purposes. These will also form part of the tender documents when hiring builders.

Building an Extension – Planning the Work

Who Will Manage the Work?

You can use a design and build company who will manage the build project for you but if you’ve used an architect or designed the extension yourself then you’ll need to find a main contractor to manage the project.

Alternatively, you could manage the build and hire subcontractors, or take on a project manager to sort it for you.

Sites like Checkatrade.com are a good place to start your search. But, word of mouth is often a great way to find someone locally — speak to friends and family and ask them for recommendations.

Finding a Builder

If there is one thing that is more difficult than finding the right builder, it is getting on with him throughout the project.

Obviously a good recommendation helps, but it is wise to talk to previous clients of the builder. You should also ensure that they have contractors all risks insurance.

If the builder has sufficient information there is no reason why they should not be able to give you a fixed price detailed quotation. Day work rates can be a recipe for disaster for all sorts of reasons. Try to avoid them except for extras requested at your behest although sometimes it is impossible to do so.

If VAT is to be added to the price given, make sure any quotation has a VAT registration number on it and a VAT receipt is provided when payment is to be made. It has been known for some less reputable operators to use the VAT system as a means of adding more onto the bill which they then keep for themselves.

Tradesmen

It is enormously helpful if you manage to find a small group of tradesmen, all of whom have several trades under their wing. This can be crucial in keeping continuity. Time wasted can prove very expensive for a variety of reasons: e.g. scaffold and plant hire, additional labour and rent.

You should also remember that anyone hiring his/her own labour effectively becomes the builder. There is no contract with a main contractor and the buck stops with you. If you take on this role, you will have to manage:

• trades
• materials
• services
• keeping the site tidy
• relevant site insurances and public liability insurance.

Safety and Disruption on Site

Try to keep the mess to a minimum. You can do this by:

• Using masses of protective plastic sheeting wherever appropriate
• Sealing off the rooms being worked on.
• Provide welfare facilities (rest area, toilet and access to a kettle) for your builders.

The vaulted ceilings in this extension and neutral colour scheme really open up the space to create a light and airy kitchen (from Naked Kitchens)

Should You Move Out While Extending?

Decide from the outset whether you’ll be able to cope with the disruption.

A large extension project with remodelling work planned might be less stressful if you move out, but for others, you may be able to seal yourself off from the dust and the work, and find it cheaper to stay put.

Always factor the cost of accommodation into your extension budget.

Adding Heating and Electrics When Building an Extension

Extending Your Central Heating

Before you start work you should reassess your heating requirements and check if your existing system is large enough to cope with the extra rooms you intend adding. If your boiler does not have the capacity it might be more economic to add a second system rather than replacing the boiler.

You may well pay less in the long term by opting for a separate electrical system rather than having to fork out a large lump sum for a new boiler. Many people opt for electric underfloor heating or electric radiators.

Extending Your Electrics

If you are adding a kitchen to your house you are likely to have to add a circuit that goes directly from the distribution board. For any other work, unless it is very extensive, it is usually possible to extend the existing ring circuit.

Ring circuits are restricted to 100m² but any number of sockets can be provided on this system.

An extension will give you the opportunity to add to your existing power points. Many people in this position take the opportunity to replace single socket outlets with double ones and install outside lighting.

Two extensions have been added to this period property as part of a major remodel

Payments

Your builder will generally stage payments for each phase of the project. Try not to make any payments upfront.

If it is necessary to purchase an expensive item perhaps a bathroom suite some months in advance of its installation, you should make sure it is in your name and not that of the builder, just in case they should go out of business.

Your designer will charge fees according to the work involved, so an accurate quotation of the fee would be a very useful thing to have before you give the go-ahead for plans to be prepared.

It is wise to check what any quote includes and who will pay any local authority application fees. Also, ask if any provision has been made should structural calculations be required.

VAT

VAT is zero-rated on new build in domestic properties including self builds, but this does not include extensions.

If you are renovating or extending a property that you can prove has been empty for 2 years or more, it will be treated as a conversion and therefore be charged at the reduced rate of 5%. The VAT concessions are only available via a VAT-registered contractor.

Main image: IQ Glass UK

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This year marks the very special 30th anniversary of Homebuilding & Renovating. Over the next 12 months, we’ll be sharing some of our favourite memories and bringing you special content to mark the occasion. Thank you for celebrating with us.

The growing sense of optimism within the construction sector is continuing, with UK construction activity in February growing at its fastest pace in more than a year. But there is concern that inclement weather may be affecting building projects.

The February outcomes from the IHS Markit/The Chartered Institute of Procurement & Supply’s Purchasing Managers’ Index (PMI) construction survey, reveal the strongest expansion of house building activity since July 2018. 

The findings are being driven by a recovery in the housebuilding sector, and follow on from housing being named the best performing area of construction in January.  

The authors hypothesise that this growth can be attributed to lower mortgage rates and a strong labour market underpinning the housing sector’s recovery.

The authors wrote: “Survey respondents noted that improved demand had translated into higher levels of business activity in February, particularly in the housing and commercial sub-sectors. Commercial construction activity also returned to growth after more than one year of contraction.” 

Prior to the December general election, political and economic uncertainty over Brexit led to reduced confidence within the sector, but the so-called ‘Boris bounce’ has seemingly resulted in a momentum shift in 2020. 

“There were widespread reports that pent-up demand released since the general election had helped to boost workloads,” said Tim Moore, economics director at IHS Markit.

Builders Taking a Rain Check

That said, you only have to look out the window to see how the weather has turned since the beginning of the year, with flooding and snow causing travel disruption across the UK. 

The PMI survey noted that, “there were some reports that severe weather conditions had led to delays on site and acted as a brake on growth.”

Bad weather can affect your self build or extension in a variety of ways, including delays in materials arriving at your build site, and weather conditions preventing work continuing on site – causing issues with timelines and costs. 

With winter weather proving challenging across the UK, adapting your self build schedule may be necessary to prevent further disruption. 

House extensions can transform how you live in your home, without you needing to move to a new property.

Whether you intend to extend up, out or to the side, there are some key things to know before your project begins, from the legalities and logistics to budgets and builders.

To help you navigate your house extension project, we’ve pulled together 25 things you need to know before your build starts.

1. House Extensions Need to Comply With Building Regs 

Even if your house extension can be built under Permitted Development rights, work must get Building Regulations approval.

The Building Regulations set out minimum requirements for:

• structural integrity
• fire safety
• energy efficiency
• damp proofing
• ventilation
• and other key aspects that ensure a building is safe.

Most repair work is excluded from Building Regulations, with the exceptions of replacement windows, under­­pinning and rewiring. However, apart from certain new buildings such as sheds, outbuildings and some conser­vatories, all new building work, including altera­tions, must comply with the Regulations.

Typical Examples of Work Needing Approval:

1. House extensions 
2. Loft conversions
3. Internal structural alterations, such as knocking down an internal wall that is loadbearing
4. Installation of baths, showers, WCs which involve new drainage or waste plumbing
5. Installation of new heating appliances
6. New chimneys or flues
7. Altered openings for new windows

(MORE: If you do need planning permission for your house extension, check out our complete guide to approval)

2. Do House Extensions Add Value?

For house extensions to make economic sense, you need to make sure the value added is greater than the cost of the project. It can be difficult to assess, but finding similar local properties and seeing how much they’ve sold for can be a useful guide.

Be aware of the ceiling value in your area, and be prepared to adjust your plans if necessary.

3. Should I Build as Big a House Extension as Possible?

Often extenders get preoccupied with only thinking of the project in terms of square metres, not in terms of what that size is adding to the house. Bigger is not always better when it comes to house extensions, and there are often ways of creating the feeling of more space, without adding a large extension.

This is often achieved through clever design, not only of the new space, but also what is already there.

4. Choose the Right Designer for Your Home Extension

When it comes to the design of your extensions, there are a number of options you can choose from.

These include:

Ask for recommendations from friends, family and neighbours, but also look online for practices that have designed projects similar to what you are hoping to build.

5. Design in Efficiency Early On

By focusing on the fabric of your new house extension, you may be able to far outstrip the U values and airtightness levels specified by the Building Regulations.

However, appending a thermally-efficient extension to a poorly insulated home will not make it cheaper to run overnight and you should look to improve the efficiency of the main house while the builders are on site.

6. Building a House Extension On or Near a Sewer

If your house extension will be built over or in the area of a sewer, you will need to contact your water board before work begins. “The location of sewers needs to be carefully considered,” Jonathan Durndell of Milton Keynes Architectural explains. “If a shared sewer (one which serves more than one property) is within 3m of your extension, then a Build Over Agreement with your local water authority is likely to be required.”

These can be tricky – and costly – especially if a new manhole is needed, or an existing one needs to be moved.

7. Extending Above a Single Storey

While it may seem appealing to extend above a single-storey extension or garage, these structures may not be able to support the load.

There are options where the old structure isn’t up to scratch: underpin existing shallow foundations; strengthen or bypass the existing with a steel frame bedded in new concrete pad footings; or demolish and rebuild. The latter is often the most cost-effective option.

8. Planning in Services for a House Extension

If you are extending your kitchen, you need to confirm the position of your units, cooker and white goods before work begins so that electrics, ventilation and plumbing can be planned in.

The same will apply if you’re building a two-storey extension and are including a new bathroom or en suite in the design.

9. Can Your Boiler Cope with the House Extension?

Adding house extensions will add demand to current hot water systems, which may not be able to cope.

It’s advised that you work out what the new extension will need to be heated effectively, and factor in your boiler output, the size of the radiators, hot water cylinder size and the reheat time.

(MORE: Heating: Beginner’s Guide)

10. Living On Site Could Slow Down Progress

It is possible to live on site throughout a house extension, but aside from all the dust and mess, you may end up slowing down progress as the builders attempt to work around your life.

If you’re not prepared to live with the disruption, then you should definitely consider looking for temporary accommodation (short-term rental, hotel or staying with family or friends).

11. Factor in Access Restrictions

If you live in a terraced home with restricted access, that may affect the options you have for your house extension design. For example, you may not be able to use certain construction methods, or you may need to make arrangements with your neighbours to temporarily remove fence panels or use their land for short-term storage.

12. Connecting the Old and the New

How well the additional space sits alongside the original property will undoubtedly affect the success of the project. While there are no hard and fast rules, you will need to make a decision on whether you want your new house extension to complement or contrast with the main house.

13. Building Off-Site Could Save Time and Money

Off-site construction systems, including cross laminated timber (CLT), oak frame, structural insulated panels (SIPs) and timber frame, often work well on house extension projects. As the name suggests, the majority of work happens in a factory off-site, and components are then delivered to site ready for erection.

14. Should I Project Manage my Own House Extension?

“I would always maintain that the best person to oversee an extension that you are proposing to utilise and enjoy is yourself,” says project manager Bob Branscombe. “No one knows the space or the building better than you, and nobody has a greater level of interest in getting it right.”

Project managing any building project requires high levels of patience, organisation, problem-solving and decision-making skills. If you don’t feel confident dealing with the problems associated with a build site or have the time available, a professional PM, main contractor or package company is a must.

15. Community Infrastructure Levy May Apply to House Extensions in Your Area

Before embarking on house extensions you should establish if you will be liable to pay the Community Infrastructure Levy (CIL). Some councils operate this scheme, and it’s applicable to extensions over 100m² in gross internal area (even if they are built under Permitted Development).

However, a self builder’s relief can apply, as Jonathan Durndell of Milton Keynes Architectural, explains: “To benefit from the self builder’s relief the applicant does not have to physically construct the extension themselves but they must intend to live at the property as their main residence for a minimum of three years from completion.

“It is advisable to check with your local council to establish if any CIL charges are applicable and the route to apply and claim relief before you start construction.”

16. Understanding the Party Wall Act

Your neighbours cannot stop you from build­ing up to, or even on, the boundary between your properties, even if it requires access onto their land (providing you have planning permission to do so, and there are no restrictive covenants).

The Party Wall Act allows you to carry out work on, or up to, your neighbours’ land and buildings, formalising the arrange­ments while also protecting everyone’s inter­ests. This is not a matter covered by planning or building control.

If your house extension involves digging or building foundations within 3m of the boundary, party wall or party wall struc­ture, or digging foun­dations within 6m of a boundary, the work will require you to comply with the Party Wall Act. In these cases you may need a surveyor to act on your behalf. The act does not apply in Scotland.

17. Site Insurance is a Must

When carrying out a house extension you need to have site insurance with an A-rated insurer to cover the existing structure and the new works until you complete the project.

Even if your builder has insurance, it is important to check their documents as the majority have liability cover which will require you to prove fault in the event of a claim, which can mean a lengthy legal battles. This may also not cover any natural events claims, such as fire, flood and storm damage.

If you are vacating the property during the build, you will require site insurance or unoccupied buildings insurance which will usually be a minimum six month policy. Always contact your existing insurance provider to notify them of works before you start.

Get a quote now to protect your project

18. Planning Rules in Conservation Areas

Permitted Development rights are restricted in Conservation Areas. Each local authority has its own policy for areas like this, but generally the basis of the policy is to prevent the loss of character of the area. So, if you’re thinking about a house extension, always contact your local conservation officer first.

19. Factor in Privacy 

Your glazing choice may have an impact on how private your home is and how exposed you are to glances in from passersby and your neighbours.

One solution would be to consider your boundary treatments, which may need to be adapted to ensure privacy is maintained, while integral screens in your glazing provide privacy without spoiling your view.

20. Check if Trees Are Protected

Some trees are protected by Tree Preservation Orders (TPOs). Even if house extensions don’t require planning permission you cannot alter or even prune a tree that has a TPO on it without planning permission.

All trees within a Conservation Area are protected by legislation and effectively have a TPO on them providing they have a trunk of diameter greater than 75mm. Altering a tree that is protected by a TPO is a criminal offence and can result in substantial fines so take care if you are extending your home near to a protected tree.

(MORE: Tree Preservation Orders)

21. Don’t Forget a Contingency Budget

A healthy contingency to cover any unexpected costs — the start of work on an extension project can uncover problems with the existing house that need addressing, for instance.

We recommend a contingency of somewhere between 10-20%.

22. You Probably Can’t Claim VAT Relief

Most house extensions will be subject to VAT on labour and materials at the standard rate of 20%, especially if you use a contractor to undertake the work. If you use local trade­smen who are not VAT registered you can save the 20% VAT on their labour, but you will still have to pay VAT on materials at the standard rate.

Some extension projects are eligible for VAT relief, such as work to listed buildings (zero rated), the conversion of an existing dwelling that changes the number of units (reduced rate of 5%) and work to a building that has been unoccupied for at least two years (reduced rate of 5%).

(MORE: Reclaiming VAT)

23. You Need to Notify Building Control of Your House Extension

Before any works begin, you will need to submit either a building notice or a full plans application to building control. A building notice will allow work to begin quickly, but you will lack the protection that building control has signed off on the design and you are liable to correct any work that fails to meet Building Regs’ standards upon inspection.

24. Light Ingress Needs to be Managed

Though bringing more light into a home is often a desired outcome of an extension project, unmanaged light ingress can create problems associated with solar gain.

Designers should be aware of this when designing glazing features into an extension and mitigate for the solar gain to avoid the situation where, like poorly designed conservatories, the extra space is usable for only a small part of the year. Screen fabrics can also be used to reduce glare and diffuse light.

25. How Much Glazing Can I Add to My House Extension?

“Part L of the Building Regulations limits the total area of glazed elements in an extension to a maximum of 25% of the extension’s floor area,” says Jason Orme, experienced extender and Homebuilding’s Editorial Director.

“Particularly on small extensions, this poses a problem. A small kitchen extension, perhaps adding 20m² of space, could easily have its allowance taken up by a set of bifolds – 4m(W) x 1.8m(H) = 7.2m² or 36% of the floor area – and will therefore be rejected by building control.

“There are several ways around this. First of all, you need to deduct the total area of the windows and doors that are being lost as part of the extension from your additional total. If that doesn’t get you below 25%, then you’ll need to show that the new glazed extension can meet the energy performance standards achieved by a non-glazed extension in other ways.

“If that still fails, then you’ll need to commission a SAP assessment to show that the CO₂ emission rate from your glazed extension would be no greater than the emission from a fully compliant extension of the same size.”

Main image: Kloeber/Lynn Palmer Architects

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This year marks the very special 30th anniversary of Homebuilding & Renovating. Over the next 12 months, we’ll be sharing some of our favourite memories and bringing you special content to mark the occasion. Thank you for celebrating with us.