Non-standard Construction: The Complete Guide [Top 9 Most Popular FAQs]

It’s important to know if the home you own or want to buy is of standard or non-standard construction. The type of construction can affect insurance costs, mortgage availability, and how easy it will be to sell in the long run.

So, what is a non-standard construction house?

Any house that is not built out of brick or stone with a slate or tiled roof is considered “non-standard construction”. There are many types of non-standard construction homes, including timber-framed, prefabricated, and steel-framed. Generally, non-standard construction houses are harder, and take longer, to sell.

In this article we’ll take a look at the different types of non-standard construction homes built in the UK.

We’ll look at why it’s hard to mortgage a non-standard construction home, and why some are unmortgageable in their original form. We’ll also cover whether it is possible to get home insurance on non-standard properties.

If you are considering buying a non-standard home, this guide will help you weigh up the pros and cons.

If you are a seller, this guide explores the challenges you may face trying to sell a non-standard construction home. You can also use this free quiz we've designed. It'll help guide you in the right direction: 

1. What is non-standard construction?

A non-standard construction house is any house that is not built of brick or stone with a slate or tiled roof.

In total, there are around one and a half million non-standard construction homes in the UK.

There was a surge in the popularity of non-standard construction housing after the First and Second World Wars. The housing shortage motivated the Government to find ways to build homes quickly, with the limited skilled labour and materials on offer.

A number of new methods of construction were developed as a result. The Building Research Establishment (BRE) has over 500 different systems listed between 1919 and 1976!

Most of the types of housing built were intended to provide permanent (or long term) housing. A handful of systems were intended only as emergency or temporary solutions.

The BRE were responsible for carrying out the condition surveys on non-standard construction homes in the 1980s. They discovered some fundamental problems that affected several concrete housing systems. These homes were designated “defective” under the Housing Defects Legislation.

No steel or timber systems were designated as defective.

Let’s now take a look at the different types of non-standard construction homes that can be found in the UK…

2. What are the types of non-standard construction?

There are hundreds of different types of non-standard construction houses. Generally, non-standard construction can be split into four categories: metal framed, timber framed, precast concrete and in-situ concrete. Non-standard roof materials (e.g., thatched roofs) and construction materials (e.g., cob) will also make a house “non-standard”.

As we said above, non-standard construction can generally be split into four categories:

1. Metal framed houses. The two most popular types of metal framed houses are the B1 Aluminium Bungalow (approx. 55,000) and the BISF house (approx. 35,000).
2. Timber framed houses. The most popular type of timber framed house is the Frameform with approximately 13,000 built.
3. Precast concrete houses. Two of the most popular types of precast concrete houses are the Cornish Units (approx. 30,000) and the Airey house (approx. 26,000).
4. In-situ concrete houses. The most common type of cast in-situ concrete house is the Wimpey No-Fines home, with approximately 300,000 built in the UK.

If a house has a roof that is not slate or tiled, it will also be classified as a “non-standard” construction home. Here are some non-standard roof examples:

• Flat roof
• Thatched roof
• Corrugated iron roof
• Shingle roof

“Non-standard” construction also includes the following:

• Alternative construction materials. Kate Hughes, insurance expert from comparethemarket, states that houses built from “some cladding, flint, straw bale, cob, wattle and daub, grass and peat turf walls” will be considered non-standard.
• Listed properties. Listed properties may be considered “non-standard” due to their outdated construction methods. They require their own specialist listed buildings insurance.

3. Can you get a mortgage on a non-standard construction home?

You can get a mortgage on a non-standard construction home unless the property type has been classified as “defective”. Your choice of lenders will be limited. This is because of the added risks associated with non-standard construction homes. You may have to accept a mortgage with less favourable terms (such as a higher deposit or interest rate).

Mortgage lenders often categorise houses as “standard” or “non-standard” construction to classify risk. Generally speaking, non-standard construction properties are considered higher risk. This makes them trickier to finance.

Mortgage lenders will consider things such as:

• Will the house represent adequate security for the loan? Certain lenders may worry that a non-standard house may not hold its value in the medium to long term.
• Will they be able to recoup their losses? Non-standard construction houses can be harder to sell. Some lenders might worry they’ll struggle to recoup their losses if forced to repossess the property.

Top tip: If you’re struggling to find a mortgage provider, speak to a mortgage broker. They will know the banks and building societies who lend on non-standard properties and who are most likely to approve your application.

You will not be able to get a mortgage on a non-standard construction home if:

1. The property type has been classified as “defective”, and
2. The home has not been repaired to the required standard.

Generally, mortgage lenders will not lend on “defective” homes, unless they are provided a PRC Certificate. This confirms that structural repairs have been carried out in accordance with an approved PRC licence.

If the non-standard property is not defective, you should be able to get a mortgage. Certain lenders are willing to offer mortgages on non-standard homes.

You may have to accept a mortgage with less favourable terms, such as a higher interest rate or deposit, though.

Related: "Can I Get a Mortgage on an Airey House? [How To Improve Your Chances]"

4. Which non-standard construction homes are considered “defective”?

The Building Research Establishment carried out a review of non-standard construction properties in the 1980s. The condition surveys revealed that certain types of non-standard construction homes suffered from structural defects. This led to them being designated as “defective” under the Housing Defects Legislation.

Not all non-standard construction houses are classed as “defective” under Part XVI of the Housing Act 1985. Most of the property types that were classified as defective are precast concrete houses. A couple of in-situ concrete house types (Boswell and Schindler) were also classified as defective.

Whether or not the property has been classed as "defective" has a large bearing on the best way to sell. Take this free quiz I've designed for you to get personalised home-selling advice.

We have put together a table of all the house types that were designated as inherently defective by the BRE.

*Houses prefixed with a “P” are Precast Concrete Houses and those with an “S” are In-Situ Concrete Houses.

5. Can you get home insurance on a non-standard construction home?

It can be hard to find home insurance for some non-standard construction houses. Unfortunately, not all insurance providers will be willing to insure a non-standard construction home. Generally, insurance premiums tend to be higher. This is because the risks and repair costs are less predictable than “traditional” homes.

If insurers are not familiar with the construction type, they may struggle to assess the costs of repairing houses if they are damaged.

You’ll need to shop around to find an insurer willing to provide home insurance for a non-standard construction property.

If you’re struggling, I would recommend speaking with a specialist insurance broker. They should be able to help you find an insurer who is willing to offer cover for your non-standard home.

Top tip: It’s worth picking up the phone to the insurance company once you’ve received a quote to make sure you’re fully covered.

6. Can you change a non-standard construction house?

Not all non-standard construction houses can be converted into a standard construction home. It will largely depend on what part of the house is classed as “non-standard”. For a house to be classified as standard construction, it needs to be made from bricks or stone with a slate or tiled roof.

Let’s take a look at some examples…

1. A brick house with a shingle roof. The property will be classified as “non-standard” because it has a shingle roof. If you replace the shingle roof with either a slate or tiled roof, it would then be classified as “standard” construction.
2. A BISF house (steel framed). Certain types of non-standard housing, such as a BISF house, cannot be converted into a standard construction house. This is because the main steel frame (that supports the property) will have to remain in place. Therefore, the house will still be deemed non-standard.

Some non-standard properties have a brick skin added to the exterior for added insulation and to improve the appearance. Just because the outside is made of bricks, it doesn’t now mean the house is of “standard construction”. The frame will still be made of a non-standard material, and so the house will be classified as “non-standard” construction.

Don’t worry if you own a non-standard construction home. It doesn’t need to be converted to a “traditional” home for it to be mortgageable, insurable, or sellable.

The one thing that will impact the mortgageability and saleability of a non-standard construction home is if:

• The house type is classified as “defective”, and
• The property hasn’t been repaired to the required construction standard (with a PRC Certificate issued as evidence).

This will make the property unmortgageable and will limit you to cash buyers if you want to sell the house.

Top tip: Make sure to double check with your local authority to see if planning permission is required to carry out the work.

7. How can you tell if a house is non-standard construction?

Some properties can easily be identified as non-standard by an untrained eye.

However, other times it might be less obvious and so you’ll need to dig a little deeper to find out the construction type.

Here are some ways to tell if a house is non-standard construction:

1. Check any paperwork. Read through any paperwork you might hold about the original construction of the home…if you can find it!
2. Enlist the help of a building surveyor. A bespoke building survey should clarify the construction type. Make sure the surveyor you commission is familiar with the non-standard construction types that are popular in your area.
3. Contact the Local Authority. Contact your Local Authority’s Building Control department to see if they have any online records.
4. Speak to your neighbours. Many non-standard construction homes were built as semi-detached or terraced properties. Speak with neighbours whose homes look like yours to see if they can confirm the property type.

If you do enlist the help of a building surveyor, they should be a member of one of the two main accrediting bodies. These are RICS (Royal Institution of Chartered Surveyors) or RPSA (Residential Property Surveyors Association).

8. Is it hard to sell a non-standard construction house?

Selling a non-standard construction house tends to be harder and take longer than a traditional home sale. Many buyers simply avoid all non-standard construction houses altogether. There is a lot of stigma associated with non-standard homes. Buyers may also be put off by the higher insurance premiums and future saleability of the property.

The best way to sell a non-standard construction property will largely depend on what you value the most: time or money.

Let our free quiz do the hard work in helping you decide how to sell your non-standard construction home: 

Best price possible.

If price is the #1 goal, then selling with a good local estate agent will generally be the best way for you to sell a non-standard construction house.

Try and find an estate agent with experience selling your property type. They’ll understand the quirks of the property and won’t inadvertently put buyers off. You want your agent to dispel any myths to buyers, not reinforce them.

BUT, if the property type is “defective” and not repaired, remember you’ll be limited to cash buyers. This will limit your buyer pool even further.

Be prepared that it might take a lot longer to find a suitable buyer selling this way.

Faster and more certain sale.

If you prioritise your time and want to achieve a faster sale, your best option is to sell by auction.

Auctions offer a great balance between speed and price.

Selling by auction is one of the fastest ways to sell your house. Sales can be agreed in as little as 6-8 weeks.

Auction also offers a much greater deal of certainty than selling with an estate agent. Less than 1% of sales agreed by traditional auction fall through. That’s a massive 30% less than those sold with an estate agent!

Auctioneers also tend to have more experience dealing with non-standard construction houses than many estate agents.

Is auction the best way to sell?

If you think auction might be right for you, and you want to save a lot of the homework, headaches and guesswork, I can help. Take the free quiz I've designed for you below to find the best way to sell your non-standard construction home.

If auction's the right option for you, I'll connect you with my #1 Leading Auction House in your area. You'll get a free auction appraisal and have all your auction questions answered (for free) in the next 48 hours.

9. Should you buy a non-standard construction house?

Non-standard construction houses are almost always cheaper to buy than an equivalent standard construction home. This can make them a more affordable option for some buyers. However, you will have limited options when it comes to finding a mortgage and insuring the property. Generally, they are also harder to sell.

Here are some things to consider before purchasing a non-standard construction home:

• Property type. What is the property type? Some non-standard construction properties were only ever meant to be temporary dwellings (e.g., the Arcon temporary bungalow). Try to find out any common problems that other homeowners have experienced with the property type. This will help flag the issues you might face in the future.
• Defective. Is it defective (and has it been properly repaired)? If the house is a “defective” type, make sure to ask the seller for a PRC Certificate. This will confirm that the repairs were carried out to an approved standard and signed off by a structural engineer. It’s also vital if you want to get a mortgage on a defective home.
• Condition. Is the condition of the house good, or will it need any repairs? You should get a structural engineer to carry out a thorough inspection to identify any issues. Make sure to take their advice on board and factor in the cost of any repairs that need doing into your offer.
• Financing. How are you planning to finance the purchase? Only certain mortgage providers will be willing to lend on non-standard construction properties. If the property type is defective and the seller doesn’t have a PRC Certificate, you won’t be able to get a mortgage.
• Insurance. It can be harder and more expensive to insure a non-standard construction property. If you’re struggling, you can speak with an insurance broker. They’ll be able to help you find a suitable home insurance policy.
• Future saleability. How easy will it be to sell the house in the future? Depending on the location and market conditions, it’s generally harder to sell a non-standard construction home compared to a “traditional” house.

Ultimately, whether you should buy a non-standard construction house will be a decision only you can make. If properly maintained, many non-standard construction properties can make great homes.

Just make sure you have enough information on the property type (from reliable sources) to enable you to make a considered and informed decision.