The original house openings
The retained sliding door and window separate the new room from the existing house. Their positions are visible on the drawing and in the finished-room photographs.
HARINGEY, NORTH LONDON · HOUSE EXTENSION
SIP rear house extension
in Haringey
More room at home.
A wider view of the garden.
Costi and the TRJ team built this rear house extension with a SIP base, walls and roof, white-rendered exterior and broad anthracite bifold doors. The finished room adds space beside the existing house while retaining its original rear door and window.
- Location
- Haringey, London
- External footprint
- 18.165 m²
- Project type
- Rear house extension
- Construction
- SIP base, walls & roof
01 / THE BRIEF
Extend the house.
Keep the connection.
Izabela wanted a single-storey rear extension. The agreed design called for a SIP-panel structure following the approved planning drawings, with a white-rendered finish and an open outlook towards the garden.
The original rear sliding door and window were to stay in place. The specification records no new breakthrough through the existing house wall, and the finished photographs show the retained openings from inside the extension.
Access was planned through the neighbouring garden, with temporary fence removal. The scope also included removing the existing canopy and extending the rainwater drainage beneath the new extension.
02 / ORIGINAL FLOOR PLAN
A rear addition.
A clear garden outlook.
The proposed drawing labels the extension at 5.19 m wide by 3.50 m deep. The order records an external footprint of 18.165 m². The detail below shows the extension and its relationship to the existing rear of the house.
Wide doors to the garden
The agreed joinery specification records a 3,500 mm wide by 2,100 mm high aluminium bifold door set, finished in anthracite grey inside and outside.
Original proposed drawing detail. Labels are reproduced as supplied; the external footprint is distinct from usable internal floor area.
03 / BUILD DETAILS
White render.
Dark-framed glazing.
The finished frontage combines a white-rendered exterior, anthracite aluminium glazing and a projecting canopy with recessed lighting. Black rainwater fittings complete the exterior.
Inside, pale walls and timber-effect flooring keep the room bright and simple. The wide bifold doors connect the room with the patio and garden.
Foundations and SIP structure
The order specifies a SIP base, walls and roof on screw-pile foundations. Pile depth was subject to the soil investigation, engineering and agreement with building control; it is not a standard depth to assume for another property.
Roof and exterior
An EPDM membrane and black round gutter system form the roof and rainwater specification. The exterior finish was upgraded to white render with a front canopy, over the specified board, membrane, batten and ventilated-wall system.
Glazing and interior finish
The aluminium bifold door specification includes anthracite frames, trickle ventilation and argon-filled toughened glazing. The interior scope includes plasterboard, skim, white Dulux paint, Howdens laminate flooring and white skirting.
Lighting and services
The recorded electrical scope includes four white double sockets, eight internal downlights and five external downlights. Drainage extensions were included for rainwater discharge, with the connection arrangement subject to building-control approval.
These details describe the agreed scope for this individual project. Foundations, structural design, services and approvals are assessed separately for each new extension.
04 / BEFORE, DURING & AFTER
From the existing rear
to a finished room.
Before the build
The original rear of the house and garden establish the starting point for the new addition.
The work in progress
The supplied construction photographs show the new frontage installed, interior fit-out and work around the garden approach.
The finished interior
White walls, recessed downlights and timber-effect flooring frame the garden-facing bifold doors.
05 / CUSTOMER FEEDBACK
Izabela’s verdict.
★★★★★ · 5/5 on Trustpilot
“The job was done to the perfection with high standards … I was really pleased with their service”
Isabela · Published · Trustpilot
Excerpt from the public “Rear extension” review, published under the name Isabela. Read the full review on Trustpilot ↗
Company-wide ratings checked on 7 November 2026. Follow the links for current ratings and reviews.
06 / PROJECT PHOTOGRAPHS
Explore the frontage.
Step inside the extension.
Browse all 18 supplied photographs, including the existing house, work in progress and the completed extension. Select any image for the full view within this page.
View the remaining project photographs
Project photographs: TRJ Construction. Images show this individual house extension at different stages.
07 / PROJECT QUESTIONS
A few useful answers.
What size is this Haringey house extension?
The proposed drawing labels a 5.19 m width and 3.50 m projection. The order records an external area of 18.165 m². These are external project dimensions, rather than a stated usable internal floor area.
How does the extension connect to the house?
The agreed specification retains the existing house window and sliding door, with no new breakthrough through the original rear wall. The completed interior photographs show this arrangement.
What are the main exterior finishes?
White render, an anthracite aluminium bifold door set, a front canopy with downlights, an EPDM roof covering and black rainwater fittings form the recorded exterior specification.
What interior and electrical work was included?
The specification includes plasterboard, skim and white Dulux paint, Howdens laminate flooring with white skirting, four double sockets, eight internal downlights and five external downlights.
YOUR NEXT PROJECT
Make room
for life at home.
Planning a SIP house extension in North London? Tell Costi what you want the new room to change, its approximate size and how the site can be accessed.
Explore our build process and discuss the design, planning and building-control requirements for your property.
