A tricky triangular plot in West Sussex

This house required imagination, determination and exemplary carpentry skills

By Emily Brooks | 3 February 2022

Every Grand Designs project has its challenges, and the triangle house in Billingshurst, West Sussex, certainly had its fair share. Featured in the 2021 TV series, the build saw Olaf and Fritha Mason tackle one of the trickiest plots ever seen on the show.

A challenging task

With its triangular footprint and steeply sloping roof, Olaf and Fritha’s home is extremely unusual. However, the quirky shape isn’t the result of a design whim. Instead, it’s a clever response to a problematic site hemmed in by a main road, a railway line and a sewer.

‘We started to look for a house almost as soon as we met, but it was difficult to f ind anything in our price range,’ says Olaf. The couple have been together for five years after meeting on a dating site. They volunteer as respite foster carers for vulnerable children at the weekends and during the holidays. ‘We considered building our own home early on,’ says Fritha, ‘but none of the plots we looked at felt right.’ Then Fritha’s dad showed them a piece of land with potential on an online estate agent’s website.

Olaf and Fritha knew that a mains sewer ran across the site of the triangle house in Billingshurst, but because there was outline planning permission for a house to be built, they assumed it wouldn’t be a problem. It was only after buying the land that they realised the sewer would have to be moved, at vast expense, if they went ahead as planned. ‘I didn’t know what outline planning was,’ says Olaf. ‘I thought I was paying for a plot of land with permission for a square house plus a sewer diversion, but that was misleading because it wouldn’t have been economically viable.’

Side cladding and windows of Grand Designs Triangle house in West Sussex

The amazing windows and doors cost a significant chunk of the budget. Photo: Jefferson Smith

Bespoke interiors

Olaf is a carpenter and joiner specialising in bespoke interiors. Not wanting to be beaten by the situation, he put his design skills to good use and came up with the idea of a house that would skim the boundary of the sewer. ‘Rather than fight it, we worked with it,’ he says.

An architect helped him turn his design into detailed drawings, which were used for the planning application and Building Regulations. ‘We realised that if Olaf devoted a year to the project, he could build a better home than we could ever have afforded to buy,’ says Fritha, who runs an ethical textiles business. The timber frame was constructed on site with hand tools. ‘I wanted to get my hands dirty and build it from scratch,’ says Olaf.

His carpentry skills and experience were essential as millimetre precision was needed from the off. ‘I had to get everything absolutely right as a tiny error in the angle of the building’s incline at ground level would result in gaining a couple of extra feet at the roof ridge,’ he explains.

Just as crucial to the project are the measures taken to block out the sound of road traffic and trains. Triple glazing and 150mm-thick mineral-fibre insulation within the stud walls, which are built up to a total thickness of 500mm, limit noise pollution as much as possible.

Sloping roof of Grand Designs triangle house with solar panels

The sloping roof is covered in solar panels to help power the home. Photo: Jefferson Smith