Full-depth two-storey rear extensions. Kitchen-diner below, master bedroom or ensuite above.
Side return extensions adding footprint across both floors — ideal for terraced and semi-detached homes.
Combined side and rear extensions over two floors — maximum footprint and room count uplift.
A double storey extension usually costs more than a single storey build because it affects foundations, first-floor structure, roof tie-ins, structural steelwork, internal services and planning. Cobin Contractors provides a fixed written quote after a site survey, so you know the full scope before work starts.
| Extension Type | Size | Cost Range (£) | Duration | Design |
|---|---|---|---|---|
|
Double storey rear — small
Typical semi-detached rear extension. 2 rooms added: extended kitchen + bedroom above. |
15–25m² | £55,000 – £80,000 | 10–14 weeks | Included |
|
Double storey rear — medium
Most common format. Open-plan kitchen-dining below, master suite above. |
25–40m² | £80,000 – £130,000 | 12–16 weeks | Included |
|
Double storey rear — large
Large rear opening with goalpost steel frame. Typically in detached properties. |
40–60m² | £130,000 – £180,000 | 14–20 weeks | Included |
|
Double storey side extension
Side return format. Common on Victorian and Edwardian semis in Leeds and Harrogate. |
15–25m² | £55,000 – £95,000 | 10–14 weeks | Included |
|
Wrap-around double storey
Combined side + rear over two floors. Highest ROI format for terraced and semi homes. |
40–60m² | £110,000 – £180,000 | 16–22 weeks | Included |
|
Architectural + structural package only
If you already have a builder and need just the design and calculation pack. |
— | £3,500 – £7,500 | 4–8 weeks | Separate |
A double storey extension is not a two-week job. We break every project into eight clear phases — each with a defined output, defined sign-off and a named person responsible on our team.
Three main double storey formats suit different property types and gardens. The right choice depends on your plot shape, orientation, planning constraints and the rooms you need to add.
Harrogate town, Pannal, Starbeck and surrounding villages.
Most double storey extensions in Leeds take around 12–16 weeks from breaking ground, depending on size, structure, access, weather, roof design and internal specification.
Larger wrap-around double storey extensions or complex structural projects can take longer.
You may need Party Wall notices if the extension involves excavation near a shared boundary, work on a shared wall or structural work close to neighbouring properties.
This is common on semi-detached, terraced and end-terrace homes in Leeds. Cobin Contractors identifies this during the initial survey.
Sometimes, yes. However, a double storey extension causes more disruption than a single storey build because it affects both floors, the roofline, structural openings and internal services.
We explain the likely disruption during the survey so you can plan properly before the build starts.
A well-designed double storey extension can add strong value because it increases both ground-floor living space and first-floor bedroom or bathroom space.
The value depends on your Leeds postcode, property type, added floor area, layout improvement, finish quality and local buyer demand.
Yes. Cobin Contractors handles RSJ installation, goalpost frames, padstones, load-bearing wall removal, structural calculations and Building Control coordination in-house.
You do not need to arrange a separate steel contractor.
Yes. After the free site survey and feasibility review, Cobin Contractors provides a fixed written quote before work begins.
The quote is based on your property, planning route, structural requirements, access, specification and Building Control requirements.
