The Hidden Costs of Renovations and Extensions

Monday, April 3, 2017

Structural Works

It’s very exciting to walk around a house and imagine knocking down walls, opening up new spaces and filling it all with light pouring through grand windows. Our most transformative renovations have involved all the above and more, but remember that whenever you alter the original structure of the house – known as a structural works – it’s going to come with a cost.

Imagine a box as the most basic structure, with each room being its own box. Period homes are typically four boxes per floor stacked on top of each other, with continuous walls going from floor to attic. If you remove or weaken one of these walls, the entire structure could be compromised.

This is where structural engineers come in, whose services will come with a fee. Their job is to find solutions that keep balance in the physics holding your home up, such as using simple columns to hold up the floor above (visible in the photo of Emperor’s Gate, above), lintels to support door and window openings or enormous steel frames and cages invisibly built into the walls. The more hidden and large scale the structural works are, the more expensive they tend to be.

While big, open plan spaces may appear elegant and simple, the work that goes into creating them is anything but.

Building Services
Plumbing, electrics, ventilation, gas pipes, heating and internet connections all come under the category of building services. Just as with every other aspect of construction, these must comply with strict building regulations to make sure that their quality, efficiency and sustainability are all up to modern standards.

If you’re building a home from scratch or renovating or extending a recently built house, building services will rarely cause a problem, but unexpected costs can arise if you’re extending a period property.

The problem is, you can’t add a new extension to a house that has out of date services and simply plug everything in. Building services that are up to date with current building regulations can’t be mixed with ones that aren’t, and even if we could get them working together, it wouldn’t be legal.

For example, if you have a period property that hasn’t had its services updated in 50 years or so and you want to add a kitchen extension to the rear, by law, the plumbing, electrics, ventilation, et cetera in that extension must comply with building regulations, which would also require replacing out of date services throughout the house. This means that walls, floors and finishes will need to be torn away and replaced in the process, turning what may have appeared to be a simple extension into a far more complex project.


Nothing is more representative of contemporary building style than floor-to-ceiling sheets of glass. The purity of the material allows it to blend with any structure, from listed buildings to modern white-rendered boxes, and the light and openness they provide can reinvigorate even the most cramped and dark homes.

But the bigger the glass gets, the more expensive it is to produce, which is why windows in period homes are usually split into smaller panes. If the structure is particularly complex, we may have to bring in specialist glass engineers, which can further add to the cost.

There’s really no way around this one: if you want big sheets of architectural glass, you have to pay a premium. If you don’t consider the cost worth it but you still want a bright, contemporary style, then Crittall windows – which we’ve used in many of our builds, including our Highgate renovation pictured above – are a popular, stylish and cost-effective solution.

Now you know a few of the costs to consider when imagining your dream home, but every project comes with unique challenges that aren’t easily predicted. If you want to dip your toe in before taking the plunge, why not use our pre-design service? It’s the perfect way to get all the information you need on costs, planning laws and timescales before you make a commitment, and you can click here to learn more.