HARROW / BUILD & EXTEND
House Extensions & Structural Works in Harrow
Add the space your home is missing, designed around how your household actually uses it.
What to think about first
A house extension adds floor area and changes how the existing rooms connect. Depending on the design, the work can include foundations, drainage changes, walls, steels, a roof, glazing, heating, electrics and finishes.
Start with the problem you’re solving. A family may need a kitchen and dining room that feels connected to the garden, while another household needs a ground-floor bedroom or a study. These briefs lead to very different layouts.
Also consider what will happen to the existing house. A deep extension can leave a middle room dark unless the design brings in light. Nearby drains, ground conditions, neighbouring properties, access and earlier additions can all affect the design. Raising these early helps your quotation reflect the real job.
Types of extension
Rear extensions
These are often used to enlarge the kitchen or living area and improve access to the garden.
Side and side-return extensions
These make use of the space beside the house. Widening a narrow kitchen can change how the whole ground floor works.
Double-storey extensions
These add space on two floors, such as a larger kitchen below and a bedroom above. They usually need more detailed planning and neighbour consideration.
Kitchen and dining extensions
Plan the building work and kitchen renovation together, so the plumbing, electrics and extraction are in the right place from the start.
Open-plan living spaces
Removing internal walls may need steelwork and building control input. It’s also worth keeping some separation for noise, cooking smells and storage.
Benefits
A layout that fits your routine
Rearranging the ground floor can reduce the feeling that rooms work against each other.
Better connection to the garden
Well-placed doors and windows can make an outdoor space easier to use.
Space for several activities
Cooking, homework and relaxing can happen in one area without everybody being on top of each other.
More natural light
Rooflights and glazing can help, provided the design also considers the rooms behind.
An alternative to moving
It may be worth comparing the cost and disruption of extending with the cost of buying elsewhere.
Value increases and planning outcomes can’t be guaranteed.
Important details before you start
Structural alterations need more than a decision about where a wall should disappear. A structural engineer should establish loads and the permanent support design, with suitable temporary support and a planned installation sequence. Steel beams, bearings, connections and fire protection must follow the agreed design. Building-control requirements, nearby drains and any party-wall matters should be identified before the quotation becomes the basis of a contract.
A clear conversation before an agreed scope
Bring your priorities, site information and any drawings into the first discussion. Review access, drainage, boundaries and the relationship with the existing rooms before the footprint becomes a fixed assumption. Relevant design, structural input and approval responsibilities should be established for the proposal. Compare a quotation against those documents, including glazing and internal finishes. Agree temporary protection, the opening into the existing house and how newly discovered ground or building conditions will be addressed.
Your questions, answered
Which extension types can we discuss?
Rear, side, side-return and potential double-storey extensions can be explored alongside the existing house and site constraints. The appropriate scope depends on your brief, design, access, approvals and structural assessment.
Can a load-bearing wall be removed?
It may be possible with a suitable engineered solution. A wall should not be removed on appearance alone. Establish the loads, temporary works, permanent support and building-control arrangements before demolition.
How far can I extend without planning permission?
There is no single allowance for every property. House type, the original building, previous additions, boundaries and restrictions all matter. Larger rear extensions have a separate prior-approval route where eligible; it is not automatic permission.
What if a drain crosses the proposed footprint?
Identify public and private drains early. Your designer and the relevant water company can advise whether a build-over agreement, revised foundation detail or diversion is needed.
Should the kitchen be designed with the extension?
Yes, developing the room layout alongside the shell helps coordinate glazing, extraction, drainage, power and storage. Keep room for existing circulation and daylight into the rooms behind.
What makes quotations differ?
Ground conditions, structural work, roof construction, glazing and the internal specification can change the scope substantially. Compare quotations against the same drawings and schedule of finishes.
For property-specific requirements, consult the relevant authority or qualified adviser. Building regulations guidance · Planning Portal project guidance
Plan the connected work
Discuss Your Project ↗ or visit our building journal for published advice as it becomes available.
YOUR HOME / THE NEXT STEP
Let’s discuss what you have in mind.
Tell us about the property and the work you are considering. We can start with your priorities and the information needed to explore a practical scope.