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Costs and included work
For roof extensions, compare the scope first: supporting structure, shell, roof shape and connection to the existing house. A price is useful only when supply and finishing work are clearly defined.
| Work / price basis | Starting indication | Scope |
|---|---|---|
| Roof extensions | Price on request | Supporting structure, shell, roof shape and connection to the existing house |
What affects your total?
Existing foundations and walls, crane setup, stairs, services and finishes can be substantial separate items. A shell and a ready-to-use room are different scopes.
What to send with your request
Send current and proposed layouts, roof dimensions, facade photos and available structural information. Include your postcode, preferred schedule and the elements that must remain, so the scope can be assessed.
Create an additional storey
A roof extension can add bedrooms, a workspace or other living space. The design needs to resolve headroom, daylight, access by stairs and the relationship with the existing facade. A flat roof does not by itself establish that another storey is feasible.
Assess the existing building
A structural engineer assesses the additional loads, load paths and foundations. The solution may need reinforcement. For an extension over a garage, the garage structure and its connection to the home require separate attention.
Coordinate production and installation
For prefabricated elements, plan transport, crane positioning and lifting access. For all roof extensions, agree temporary weather protection and how the occupied home will be protected. A short lifting operation is only one stage in the complete programme.
Specify what completion means
Distinguish the structural shell from insulation, stairs, services, plastering, flooring and painting. Agree permissions, materials, the schedule and outstanding-item checks before work starts. Use the cost guide to compare complete project scopes.
Explore services and costs
From preparation to handover
The sequence is tailored to your project. See what is prepared, carried out and checked at handover.
Space requirements
Decide which new rooms and usable floor area you need.
Site survey
Assess the existing roof, load paths and access.
Design
Develop the height, façades, daylight provision and stairs.
Structural design
Have the additional loads and their transfer through the building calculated.
Permits
Have the design and local rules assessed.
Quote
Itemise the shell structure, installations, finishing and lifting work.
Construction planning
Plan the lifting position, suitable weather conditions and temporary protection.
Opening the roof
Open the roof in a controlled way and protect the home.
Installing the structure
Build the walls and roof in accordance with the structural design.
Weatherproofing
Complete the windows, doors, roof covering and connection details.
Interior work
Install the stairs, services, insulation and interior finishes.
Handover
Inspect the connections and finishes together.
Frequently asked questions
Can every home support an additional storey?
This needs assessment first. New loads must be transferred safely to the existing foundations. The staircase opening and structural connections are part of that assessment.
How do I choose between a prefabricated and site-built additional storey?
Compare design flexibility, transport and crane access, structure and finishing. Include preparation and interior work; installation time on the roof is only one part of the project.
When can construction of an additional storey be scheduled?
Scheduling needs a sufficiently developed design, structural preparation and clarity about permissions and deliveries. Also discuss weather-dependent work and temporary protection of the home.