Extension and remodel

Coming home

This case study is from SelfBuild & Design January 2021 | Buy this issue | Subscribe

Matt Stockton learned some valuable lessons when he took on a remodel/extension in his native Cheshire.

A 12m rear extension has been added to the Victorian semi and the loft converted to an extra bedroom. 

In Brief

Having worked down south in design management after graduating in architecture, I decided to return to my native Cheshire with my wife to be closer to my family. Our intention was to rent for a month while we sold our home in Northamptonshire and looked for a new one. However, this took longer than expected. We considered various properties of all shapes and sizes, from bungalows to an apartment in a country manor.

When Karolina got a new job in Cheshire East, our search became more focused around Crewe, where we were renting. We had made an offer on a split-level bungalow near Sandbach but were having second thoughts as it was priced above market value.

When we spotted Rose Cottage online, we immediately booked a viewing because of its location and agreed a sale within a couple of days. However, our homebuyer’s survey revealed the Victorian semi would cost around £50k to bring up to scratch, so we renegotiated the price, with the sale finally completed in May 2019.

We wanted to add an extension to turn the house into a functional family home. However, our pre-planning advice submission came back with several negative comments.

Our pre-planning advice submission came back with several negative comments.

They didn’t like the larch cladding we had chosen to soften the extension as it would be visible along the neighbouring garden. The planners wanted something more consistent with the original brick house. We didn’t feel this was suitable for a 12m extension in a back garden. The report also referred to a loss of light for the neighbouring properties, but we had demonstrated that this wouldn’t be the case.

To ensure the best chance of approval we approached a local councillor who visited our site before our formal application was made and he really supported the design.

MHA Architects had refined our initial sketches and simplified the design so there was no need to prop and insert new steelwork to support the outrigger that would integrate the old kitchen with a new one.

The extension forms a light and modern kitchen and sitting area with direct access to the garden through large sliding doors.

We wanted a link with the garden so that the kitchen and living area were visibly connected to the outside. This would be achieved with large glazed doors which could remain open throughout the day during the summer.

Our plans were approved, with a modification that the ridge height be lowered by 300mm as it was considered to be too imposing.

Due to the neighbouring extension wall dating back to 1880, with the foundations comprising only four bricks on edge, we opted for a thicker ground-bearing slab with a localised thickening along the abutting property as this would become a party wall. 

Most of our house was stripped back to brick with a new damp course installed on the ground floor, including the neighbour’s external wall.

The existing rooms at the front of the house were widened and heightened with the beam left exposed and fire protected as it supports the structural wall.  

The formal dining area adjoins the new kitchen but is a separate space. 

A first-floor bedroom dividing wall and corridor were removed to make a suitable fire escape and to allow space for new stairs to the loft conversion.

The ceiling on the first floor was lowered to provide sufficient height for the loft room above. 

Light was a major consideration and thankfully the existing windows were big enough to do this. In the new loft a roof light at the front and a large window at the rear mean that the loft bedroom has great views on both sides.

Light was also maximised in the rear extension with the installation of three Fakro flat sky lights – the biggest in their range.

The extension is naturally lit from above from three large flat skylights in the roof that are the largest in the Fakro range.

The full-width and full-height glazed doors, along with an opaque four-metre window to the side of the extension, make the space bright on even the darkest of days.

A high specification build

We wanted a high specification build, so the roof extension is insulated with Kingspan, with double layers of acoustic plasterboard installed on the roadside front bedroom walls to reduce background noise. Thick insulation has also been fitted in the floor, cavity and roof of the extension so that even with the extensive glazing the 45sqm space retains much the same temperature day and night.

In the winter, infrared panel heating, chosen for its energy efficiency and health benefits, keeps the space warm, while traditional radiators heat the old parts of the house. 

My experience of working in the construction industry on commercial projects proved to be beneficial in so far as I had contacts with different suppliers. For example, the parapet capping and the continental-style aluminium windows which tilt, turn and open internally, were supplied by companies I knew well. They were able to supply to any agreed size as well as advise on preparation, lintel positions and so on.

One thing that wasn’t really planned so well – common with many refurbishments and new builds – was the costings.

I had anticipated that the build would cost between £60k and £80k, a figure which we well exceeded. This was partly down to not factoring in some fundamentals and underestimating the time and labour required. We didn’t envisage relining three-quarters of the interior but as more and more plaster was damaged it seemed best to remove it all upstairs.

The Firestone rubber flat roof also had to be reviewed after only four months and another section installed around all roof lights – again, an unforeseen cost.

Another reason for our overspend was not obtaining correct breakdowns for the amount of materials required. At times it felt that we could have built an entire new house with the amount of materials ordered.

When it came to the fit-out, we wanted some luxury items, which came at a cost. For example, the Lusso stone bath, weighing 160kg, required a builder, two plasterers, lifting equipment and reinforced floor joists for its installation.

A Lusso stone bath weighing 160kg has been installed in the bathroom.

Other purchases were bargains. Our budget white lamella kitchen was later fitted with gold-coloured handles to replace the original white finger-pulls which weren’t really practical. This little change made a dramatic difference. Another good buy was the upstairs bathroom double sink. We had originally ordered an expensive one. When it didn’t arrive we subsequently found a near identical replacement at a fifth of the price. Another small saving was using some of the scaffolding boards to support the sinks, with the chrome pipework exposed beneath. 

The floorplan

This this Victorian semi has a 12m rear extension and the loft converted to add an extra bedroom. The extension forms a light and modern kitchen and sitting area with direct access to the garden through large sliding doors.

We couldn’t have achieved what we have without the help from our fathers, with Karolina’s dad flying over from Poland. We also had my uncle do all the joinery. For the building work, we employed a local contractor to construct the shell of the extension, brick in the chimney breasts that we stripped out, and build the loft dormer which required five 200kg steels. We also employed a damp specialist, electrician, plumber and plasterers.

At times it felt that managing the project ourselves wasn’t actually saving money as the timing of each element wasn’t always perfect. For example, the plaster was completed downstairs while there was no roof upstairs. I learned my lesson when I had to rush home from work to cover it with a tarpaulin in driving wind and rain.

Most weekends and some evenings were spent prepping and working at the house.

This was tough because we found out just after buying the property that Karolina was pregnant. Our son was born about six weeks before the house could be considered ‘livable’. From watching Grand Designs, we know that starting a build often coincides with the owners expecting a baby. Having experienced this first-hand I can only say it is really tough for everyone. But we got through it all and finally moved in on Christmas Eve – which felt absolutely fantastic.

The extension specification

The traditional block construction has a large cavity to accommodate 100mm thick insulation plus a 50mm air gap. This, along with the 120mm underfloor insulation and roof insulation combined with Siberian larch cladding provides a well insulated room that has a steady year-round temperature.

The extension roof build-up is internal plaster, 200mm C16 joists, 18mm structural OSB, Kingspan TP10 100mm, 3mm ply, and Firestone rubber roofing.

The slab was oversized at 200mm due to not having a conventional foundation and only a thickening on one side to alleviate pressure on the neighbour's wall.

The loft

The loft has high performance Kingpsan Kooltherm insulation throughout with 60mm fire-rated plasterboard between the neighbouring property. A 200kg beam was installed at the roof ridge along with three lower steels for the new floor level.

Valuable lessons

We used the best specifcation insulation in the loft. This was costly though the difference in U-values was negligible and the effects not felt inside. We could have saved ourselves a few thousand pounds.

Some of the existing plaster was hard to remove and we ended up spending a lot of money rehboarding/ skimming the house. In retrospect much of the existing plaster could have been retained. I estimate it cost us an additional £6,000 and the plaster today doesn’t seem as tough as the original.

We would explore using galvanised shelf angles rather than costly insulated lintels as the former can be insulated behind to prevent thermal bridging.