ADACON UK

    How Much Does a Modular Granny Annexe Cost?

    Every Adacon annexe is priced from its exact configuration — the number and size of modules plus the fit-out you choose. Design it online for an estimate; the building price includes factory fit-out and internal electrics.

    Adacon Technical Team · Published

    What drives the price

    Number and size of modules, kitchen and bathroom specification, doors, glazing, cladding and finishes.

    Quoted separately

    • VAT
    • A prepared base
    • Transport, offloading or craning
    • Final connection to mains services
    • Planning and building control fees

    Get a real figure

    Use the online designer for an estimate, then request a formal quotation for your site.

    Worth knowing: Planning, Building Regulations and council tax depend on your site and how the annexe will be used. Confirm with your local planning authority and building control before ordering.

    Where to go next

    P300 / P400 / P600 range

    P300 unit
    2.9m × 2.2m externally; approximately 2.7m × 2.0m usable internally
    P400 unit
    3.9m × 2.2m externally; approximately 3.7m × 2.0m usable internally
    P600 unit
    5.9m × 2.2m externally; approximately 5.7m × 2.0m usable internally
    Configuration
    Mix P300, P400 and P600 units to create tailored footprints and shapes
    Unit height
    2.40m external / 2.16m internal
    Storeys
    Up to two storeys, subject to final project design
    Delivery
    UK mainland and Northern Ireland — transport quoted separately

    Adacon modular buildings use P300, P400 and P600 units with external lengths of 2.9m, 3.9m and 5.9m, a common 2.2m width and 2.40m external / 2.16m internal height. The sizes can be combined to create more tailored floor areas and building shapes, joined side by side or stacked to two storeys subject to the final project design.

    Design your modular building online

    Set the layout, windows, doors and fit-out and see a live estimate as you go.

    Open the modular builder

    More guides

    What Is a P600 Modular Building?
    How Much Do Modular Buildings Cost?
    Do Modular Buildings Need Planning Permission?
    Can Modular Buildings Be Two Storeys?

    Buildings this applies to

    Garden RoomsGarden OfficesModular OfficesSite OfficesSite Welfare UnitsModular Toilet Blocks
    What do you need to build?

    Design options

    Two-Storey BuildingsGround TerracesFull-Height GlazingPitched Roof Buildings
    All design options

    Get a price for Modular Buildings

    Tell us what you need and we'll come back with pricing and lead times — usually within one working day.

    So we can call you back about your enquiry

    Enquiring about: Modular Buildings

    No obligation. We reply within one working day.