House Extension Project

We got planning permission on 10th September 2024. We have a structural engineer currently working out the steel/lintel specifications required and building control documents drafted. We are currently talking to a few builders to get quotes to start building in early 2025.😎

This project describes the extension we are adding to our existing home.

We moved into this newly built house in December 1995. The existing utility room was removed when the kitchen was redesigned back in April 2009. The 4m × 5.5m conservatory was added in March 2009.

Before we considered extending our home we also looked at other options, including a smaller, single-storey extension.

The main reasons for progressing this extension are:

Proposed Extension

The proposed extension creates three new spaces on the ground floor. The first floor covers the footprint of the old conservatory but also extends along the whole of the back of the property.

  1. A combined kitchen, dining room and garden lounge area (shown in red) and also encompassing the old kitchen and dining room. This will have 5.5m wide bi-fold doors along length exposed to our rear garden. The sun will shine through these doors early in the morning and late in the evening during the summer.
  2. A long narrow utility room (shown in blue). The existing back door will remain and a new door from the kitchen will enable access into the utility room.
  3. The existing lounge will no longer accessible via the arch from the old dining room, creating a separate space for entertaining.

In addition to the first floor extension, we are also extending upwards over the old conservatory footprint. We are running running the second storey all the way along the back of the house as this would affect our neighbours.

Solar Roof

We are planning to fit 'in roof' solar panels to cover the new extension roof. This will give a cleaner more integrated look and the solar solution we are looking at is designed to integrate with our planned Velux windows too.

Open Plan Space

The main part of the extension will a new large (~7.0mm × ~7.5m) open plan space that encompasses the old kitchen and dining room.

Utility

A large utility room will occupy the full depth of the extension (7.5m) and be over 1.5m wide internally. At the far end will be food storage cupboards and along one wall wil be a worktop over the main appliances (washing machine, tumble dryer, drawer freexer, beer fridge, etc. There will also be a sink in this room. The gas boiler will remain inside this space too.

An outside tap will sit on the external side wall.

Kitchen

Our current plan is to use darker cabinet doors along the back wall of the kitchen, which will be carried over to the other side of the kitchen door and along the whole length of the back wall as storage cabinets.

We plan to use kitchen cabinets and drawer fronts with integrated handles at the top and no handles mounted to the fronts.

Water Softener

We plan to fit a water softener as the water in our area is really hard. The model we have chosen is compatible with the Quooker tap.

Quooker Tap

We plan to fit a Quooker tap over the kitchen sink.

HVAC

We currently have a 'Worcester Bosch Greenstar 18Ri Erp + NG' gas boiler for our space heating and hot water. We have no real reason to replace this as it was only installed in 2022 and is very efficient. Gas is also very cheap, at around 4p/kWh on the Octopus Energy Tracker tariff. Our current system also includes an unvented (mains pressure) hot water storage tank. I investigated swapping out the gas boiler for an Air-Source Heat Pump (ASHP) as part of the wider plans to update our home but, it is simply not viable. The HVAC plans and implementation are described in a lot more detail here.

Air Conditioning

We are adding an air condition unit like this Fujitsu AOYG18KBTA2 system, to provide independent cooling over the summer in the open plan space and the new master bedroom above it. In operation this will use less than 2kW and typically much less in operation.

Hot Water

We plan to keep our gas boiler but, we will change the hot water cyclinder to one that is heated directly and can also be heated by spare solar energy. This gives us flexibility when energy prices and tariffs change.

Lighting

The main ambient lighting will be split into four zones/groups with dimmable ceiling mounted down-lighters. There will also be some feature task lighting over the kitchen worktop:

  1. Kitchen Lights - Ceiling mounted lights (orange)
  2. Kitchen Worktop Lights - Hanging feature lights over the worktop (yellow)
  3. Breakfast Room - The space next to the breakfast bar (blue)
  4. Dining Room - Ceiling mounted lights over the dining area (purple)
  5. Lounge - Ceiling mounted lights over the main lounge area (green)

The technology behind these is described in this project/review. We have given each group of lights a name that is used by our Home Control System and also by Alexa. This is to enable fully configurable, flexible or intelligent control via my smart home, voice control or physical switches. 'Open Plan' is a group that encompasses the four main groups of ceiling lights.

We plan to have 'Kitchen Cabinet Lights' underneath the wall mounted kitchen cabinets. We also plan to have various task lamps/lights in this space.

We plan to have 'Kitchen Counter Lights', which are an LED strip running along the underside edge of the kitchen worktop.

At both sides of the bi-fold doors, we plan to mount these 'swirl' dimmable LED wall lights. Each will have its own smart dimmer and light switch.

Entertainment

We are planing a 85" smart TV on the utility room wall with wall mounted KEF T-Series flat panel, T301 left & right speakers + T301c centre speaker.

Office/Bedroom

As part of the extension we are converting the new roof space into an office/bedroom. This second floor space will be accessed via a new set of stairs in what was our daughter's bedroom. The stairs will be behind a fire door and 80cm wide. The actual room space will be 3m wide × 4m deep but, the sloping roof will intrude such that only the central 60% will have a ceiling height above 1.8m.

Because we don't have a wet heating system that extends above our first floor, we intend to fit electric underfloor heating in this space, which is 3m wide by 4m deep = 12m². The system heat output is 140W per m², so peak power usage will be 1.68kW. This heating will be under smart control via a smart thermostat. Underfloor heating is slow to respond to changes, so it will mostly be used when the office is utilised as a guest room.

We plan to move our smart oil heater project into this office space, to avoid using the electric underfloor heating much of the time. This will be much more responsive to requests to change the temperature and as the project describes, it uses occupancy sensing to intelligently automate it.

To allow daylight into the office, there will be four Velux windows with blackout blinds. These will also be used to keep the space ventilated and cool.

Furniture

The office will have low level storage on one side and a desk with large monitor. On the other side will be storage and a folding sofa double bed.

Main Bathroom

We have gone for a modern look in the new main bathroom, with chrome fittings and white bath, shower, toilet, shower, etc. We are use 'feature' wall panels behind the bath and shower and a fairly plain tiled floor finish, with a cooler tone.

The extension incorporates our old main bathroom and significantly extends it. The new 'bathroom' will have:

  • A feature wall behind a free-standing bath.
  • A large walk in shower (1.8m × 0.8m).
  • A sink / cabinet unit with storage.
  • An illuminated and heated mirror over the sink with shaver socket to one side and a wall mounted tooth brush charger.
  • Toilet.
  • A smart home controlled, tall open-ended radiator/towel rail with electric element and illuminated momentary switch to activate it for a set period of time (for use in the summer, when our central heating is off).

The bathroom will have its own slave processor to monitor and control most of the smart home features and will be part of my Home Control System. This includes intelligently controlled, dimmable lighting in the ceiling, inside the wall niches and under the cabinets.

Master Ensuite

We have gone for a modern look in the new master ensuite bathroom, with brass fittings and white bath, shower, toilet, shower, etc. We are use 'feature' wall panels behind the bath and shower and a fairly plain tiled floor finish, with a warmer tone.

The extension extends my our daughter's bedroom significantly and adds a new walk-in wardrobe and an ensuite bathroom which will have:

  • A huge walk in shower (2.2m × 0.9m).
  • A sink / cabinet unit with storage.
  • An illuminated and heated mirror over the sink with shaver socket to one side and a wall mounted tooth brush charger.
  • Toilet.
  • A smart home controlled, tall open-ended radiator/towel rail with electric element and illuminated momentary switch to activate it for a set period of time (for use in the summer, when our central heating is off).

The master ensuite will have its own slave processor to monitor and control most of the smart home features and will be part of my Home Control System. This includes intelligently controlled, dimmable lighting in the ceiling, inside the wall niches and under the cabinets.

Smart Home

All the doors in and out of these new spaces will have wired door contact sensors and there will also be wired PIR sensors. These will be used for occupancy and presence, to intelligently light up the kitchen under cabinet lights and under worktop lighting.

Smart Blinds

We plan to have three smart blinds over the 5-door bi-fold doors with a 1-2-2 configuration, the '1' being the main door to enter and exit the garden. These can be manually controlled by three MK Grid Plus K4900 switches mounted on a 6-gang switch plate (the lower three switches are used for other lighting) but, mostly they will be intelligently controlled by my Home Control System. They can also be voice controlled the lounge Amazon Echo.

Each smart blind will be controlled using a Shelly Plus 2PM and we have already extensively tested these. There is a web interface and an app to configure and control them directly.

Even with a 45mm deep back back box, there will not be enough room to comfortably mount the three modules behind the switch plate. To create more space I am using these over size, HGS68 boxes and only exposing the top half through the plaster board. These are 48mm deep × 134mm wide × 135mm high. The bottom half will have a cover fixed to it, which is hidden behind the plasterboard. This will provide plenty of space for the wiring and Shelly modules, which will even fit edge out.

Robot Vacuum Cleaner

Because we have a large flat floor area, we are installing a hidden docking station in the new lounge area for a robotic vaccum cleaner. This will be able to keep the whole open plan area clean.