Ask the Expert: Prefab-ulous

Discover how kit homes can offer a streamlined approach to your self-build project, while minimising risks along the way. Baufritz’s Oliver Rehm sheds light on some important FAQs

What are kit homes & modular solutions?

A kit home looks the same as any other self-build, the key difference is the way the building components are assembled. Rather than materials arriving on site to be assembled by tradespeople, most of the construction takes place in a factory and these finished modules are then shipped to the site and assembled like a giant jigsaw puzzle. 

The two main options available are a shell, and a full turnkey solution. A shell, as it implies, includes the walls, roof, windows and floors. In this case the self-builder finds contractors for the internal finishes. A full turnkey solution delivers the finished house. The amount of work done onsite depends on the manufacturer. Some companies deliver the house almost complete, others allow more customisation onsite.

One important factor is that kit house manufacturers may not include foundations and groundworks. So make sure they have a partner who understands the process, as there is very little margin for error when measuring the floor slab. Some groundworks companies are not used to delivering to these tolerances.

What should I consider when building a modular house?

As we have already discussed, how much of the project do you want to manage and how much do you want to hand over to the kit home manufacturer? This will then determine whether you go for a full turnkey or a shell solution. Most self-builders who choose the kit home route do so because they do not want the risk of managing the project and the appeal of a full turnkey solution is what motivates them in the first place.

It is important to involve your architect in the process. As the house is manufactured, the designs must fit the system. This requires customisation and some options may not be possible. One of the advantages of a kit home is that you know the house will be delivered once the manufacturing plans are complete. Some companies have a limited range of houses so they will not accept designs from external architects. Others are flexible and can adapt most designs to their system. It is worth investigating to find the correct match.

Most manufacturers offer a range of materials and finishes, in which you can go to their sampling centre and have a look in person at what they offer. This can be an enjoyable but intense few days where you select all the internal and external elements of your home.

What does a modular solution cost and how should I calculate my budget?

How much should you budget for your home? It depends. Different manufacturers target different market segments and costs can vary greatly depending on materials, designs, and flexibility. It is worth checking what is included and that the materials used – as value is not the same as the price. Site clearance and groundworks are not usually included and check if your manufacturer has a partner. They can work together to produce a single price for all the work. 

The initial cost of a kit home may seem higher than a traditional self-build approach. A key factor to consider is risk. Once the contract is signed, costs and timescales are fixed. The risk of contingencies and contractor problems is greatly reduced as the house is manufactured to a standard process. Quality control is easier to manage, meaning that elements are built to millimetre tolerances.

How would I manage the construction process?

The main advantage of the kit approach is that most of the project is managed by the manufacturer as they are responsible for delivering the house. An initial price is agreed upon for designs and schedules. Once the fixtures and fittings have been selected, a final fixed price contract is usually drawn up. Manufacturers offer a wide variety of fixtures and fittings, allowing clients to choose a range to suit their budget. Once all the elements have been agreed, the client signs the final contract, where the budget is fixed. Although it is possible to make changes once the build has started, it is difficult to do so. It is important to be sure of your decisions in advance. At this point, it is in the hands of the manufacturer and almost everything happens offsite.

Are there any design constraints when creating a modular build?

This is an important part of the kit home route. If you choose a timber frame manufacturer you will get a timber frame house. There will be some restrictions on the materials and design itself, but these ‘building blocks’ of the approach are why the manufacturer can deliver consistent quality and a fixed price. There is a wide range of options available on the market. Some manufacturers supply a small range of houses to focus on cost and quality, while others offer a wide range of custom options. By definition standard building elements are used for all houses.

How is innovation transforming modular house construction?

Innovation is a key driver for kit home manufacturers. Because we use modules and systems, we know how they perform and we can invest in R&D. As an industry, construction has lagged behind when it comes to resource usage and sustainability. Manufacturers can focus on materials and supplier networks – we want to create sustainable houses. This is possible because we use common materials in every house and our processes are optimised to minimise waste. Consistent standards and quality control mean that we can produce very well insulated homes that lower energy consumption, and CO2 emissions.

Oliver Rehm is CEO at Baufritz UK