Self-build vs custom build

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What’s the difference?

We’ve all seen Grand Designs and the ups and downs that come with building a house from scratch. And you might have heard the terms self-build and custom build in the press and from associations like NaSCBA. But practically, what’s the difference between the two?

Put very simply, self-build is when you take on all the risks yourself. You also have the final say on everything.

With custom build homes, some of the development has been done already, which reduces your risk, but it does mean that some of the choices will have already been made.

Self-build

In a self-build project, as the name suggests, you are going it on your own. From finding the plot of land for sale, getting planning permission, to hiring architects, builders and other contractors. If anything goes wrong (and if you’re a Grand Designs fan, you’ll know that happens a lot!), then you are responsible for sorting it out.

A common misconception is that creating self-build housing means that you have to learn how to drive a digger and plumb a sink in. In fact only 8% of people* actually do some of the work themselves. Most self-builders either do the project management (and hire the entire team) or pay a company to do it all for them.

Whichever route is taken, self-building a house tends to be best for people who have a healthy risk appetite, lots of time, or are happy to pay someone to do it for them. It tends to suit property professionals who know what they are doing, or people who want total control.

It’s also the best route for people who want to save the most amount of money on their new home as long as they don’t have a time constraint. It’s not uncommon for people who do a lot themselves to take ten years to build their own home.

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Custom build

Custom build is what Unboxed Homes specialises in. This is where we have already done a lot of the hard work. Custom build comes in many forms, but, depending on where you are in the country, the main routes are the following:

  • A serviced plot
    This is where the developer has bought a larger plot of land and carved it into smaller plots. They will have run drains and other services to the plot along with roads and you will then take it on from there. The plots will have planning permission for either a detailed design or an outline design.
    If it is an outline design, you can use your own architect to design the rest of the home. You will probably have to adhere to a design code, eg., homes of a particular size, height or look. Make sure that you don’t buy a plot of land without planning permission unless you have had expert advice. Many people have lost thousands of pounds thinking that a plot of land in agricultural green belt can become a home. It very rarely can!
    You can rely on Custom builder developers who are members of NaCSBA as they have to adhere to a Code of practice and selling a plot with hope value is at best highly unethical and at worst illegal.

  • Shells
    This is where the developer has build a watertight structure. From the outside, a custom build shell will look finished. It’s only when you walk through the front door that you will find all of the inside missing!
    If you’ve ever witnessed a large renovation project, you’ll know that they often start with ripping all of the inside out to start again. A shell is essentially the same as that. There are also ‘warm shells’ where the developer has put some services in, eg. heating and electrical circuits. This leaves you with less to do, but warm shells will cost more than a standard shell.

  • Turnkey
    This means that you order what you want (within the menu of choices that the custom builder offers) and the developer delivers it. It’s very similar to ordering a new car. You choose colours, layouts, types of kitchen etc. This is a very convenient way to buy and self-build a house, but it will cost more than either of the other routes and your choices may be somewhat limited.


At Unboxed Homes, we specialise in homes in London and the South East and so we build shells. This means that we will have sourced and bought the land, got planning permission, and all other consents like party wall awards. We will also manage some of the trickier and riskier parts of the build like ground-works, foundations, and the structure.

For obvious reasons, you cannot sell serviced plots for flats. It’s possible (but very difficult) to do for terrace homes, so when we are working on small sites, we think that the best option for our purchasers is to build our homes as shells. This gives our purchasers the freedom and flexibility to choose layouts, finishes, and specifications, and create their own self-build designs.

Over the years, we've worked on a handful of custom build projects throughout London - here are a handful of our projects.

* Source: NaCSBA research

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