- Planning authority
- Royal Borough of Windsor and Maidenhead
- Postcodes
- SL4
- Noon sun, 21 March
- About 39°
- Shadow from a 5 m eaves line
- About 6.3 m
- Planning plan
- Local Plan
- County
- Berkshire
How it plays out in Windsor
How the two households will live together shapes the planning case as much as the drawings do. If your parent will eat with you, share the garden and rely on you day to day, an annexe is the natural fit, and that is what the Royal Borough of Windsor and Maidenhead will expect the application to describe. If your son or daughter will run their own home, pay their own bills and perhaps sell up one day, it is a separate dwelling and will be assessed against the council’s Local Plan as a new house. For a family in SL4, we help set that out clearly from the start.
What happens next in Windsor
Here’s what happens next for a family home in Windsor. You tell us about your plot and who the home is for, and we carry out a free desktop appraisal of access, space and the planning context. If it looks viable we visit, then set out the annexe and separate-home options. With your go-ahead we survey, design and give you a written quote, then prepare the application for the Royal Borough of Windsor and Maidenhead.
Free plot appraisal
We look at your plot, access and the planning picture from the desk, talk through who will live in the new home, and visit if it looks viable. There’s no cost and no obligation.
Survey and design
A measured survey, then a design built around the person moving in: step-free routes, a ground-floor bedroom if needed and privacy for both households. You get a written quote after design and survey.
Planning and approvals
We prepare and submit the planning application and manage it with the council, which makes the decision. Before work starts, approval under the Building Regulations is in place and any CIL exemption has been claimed.
Build and handover
We build while you carry on living next door, with access, deliveries and working hours agreed up front. At handover you get the completion certificate and the paperwork you’ll need for council tax, lenders and any VAT claim.
Worth checking early
- VAT savings available on a separate dwelling often don’t apply to an annexe; take advice from a tax adviser before choosing.
- Planning is the council’s decision, and an annexe is not a way round the rules that apply to a new house.
- An annexe tied by planning condition usually can’t be sold or let separately, which limits flexibility later.
Windsor: questions to ask
Is CIL payable on a family home in Windsor?
Only if the Royal Borough of Windsor and Maidenhead has adopted the Community Infrastructure Levy, which its website will confirm, and we check it for you during the appraisal. Where it applies, self-build and residential annexe exemptions exist, but both must be claimed before work starts and can be withdrawn if the home is sold or let within three years of completion.
Can I reclaim VAT on a family annexe in Windsor?
Often not. HMRC’s guidance gives an annexe that can’t be used or sold separately from the main house as an example of work that can’t be zero-rated, and the DIY housebuilders refund scheme asks the same question. A separate dwelling is usually treated differently. Take advice from a tax adviser before you settle the planning route, because the wording of the permission matters.
Who owns an annexe built in my Windsor garden?
You do. An annexe stays on the title of your house and usually carries a planning condition tying it to the main home, so it can’t be transferred to the relative living in it. If a family member is paying towards it, record what they’ve put in and what happens on a sale in a written agreement drawn up by a solicitor.
Can you design a home in Windsor for a relative who uses a wheelchair?
Yes. The design can include a level approach and threshold, turning space in each room, a wet room, wider doors and worktops at a usable height. Where the Royal Borough of Windsor and Maidenhead requires a particular access standard through planning, the design meets it; otherwise it’s your choice how far to go. Input from your relative’s occupational therapist is well worth having.
Other options in Windsor
- Planning promotion for your garden plot
- Corner and side plots
- Garage courts and yards
- Garden plot option agreement
- Sell part of your garden
- Plot feasibility and design

