House extension plans
House extension plans: start with the layout, then take the right route
If you think an extension is the answer, you do not have to leap straight into planning drawings. First establish how the house could work, what you are trying to gain and whether the idea is worth taking forward.
PlanBuild starts with the existing home and your wish list. From there, the project can move into a tested layout, planning drawings, Building Control information and, where it fits, a build route.
Short answer
What this means
House extension plans can mean anything from an early layout idea to a planning or technical drawing set. The right version depends on what stage you are at and what the project needs next.
For your home
Why it matters
A plan is not paperwork for its own sake. It lets you decide whether an extension solves the actual problem before you spend on permissions, engineering or construction.
Next step
What to do now
Send your existing plan, photos, a sketch or a listing and tell us what you need from the house. We will help you choose whether to explore layouts first or move straight to the appropriate drawing route.
Who is behind the advice
Local project advice from Josh and PlanBuild.
The page exists to help homeowners work out the practical route before drawings, structure, permissions and builder pricing become separate conversations.
Who
PlanBuild gives local project advice for homeowners around Poole, Bournemouth and Dorset.
How
We start from photos, address, existing plans, site constraints and the likely approval or build route.
Why
The aim is to point you at the right next step before you waste money on the wrong drawing, quote or contractor conversation.
Good fit
- You want more room but are unsure where it should go.
- You need to compare extending, reconfiguring or moving.
- You want a clearer brief before planning or builder conversations.
Not the right route if
- A construction quote before the scope has been defined.
- A guarantee that a particular extension can be approved without assessment.
What to send first
- address
- photos inside and out
- estate-agent or existing floor plan
- your wish list and any non-negotiables
Related routes
Keep the route connected
Extension floor plan ideas
Extension floor plan ideas show different ways a home could be extended or rearranged before you settle on a design, apply for planning permission or ask a builder to quote.
Open route →Single-storey extension layout
A single-storey extension layout explores the relationship between the new space and the existing home before a preferred design moves into planning or Building Control drawings.
Open route →Planning drawings
Planning drawings explain the existing home, the proposed change and how the project sits on the site so the council can assess it.
Open route →Building Control drawings
Building Control drawings and supporting information help inspectors assess structure, insulation, fire safety, ventilation and the construction details that matter on site.
Open route →Questions homeowners ask
Before you choose the route
Do I need planning drawings straight away?
Not necessarily. First work out whether the proposed extension and layout are worth pursuing. Once the direction is clear, we can advise whether planning drawings are needed.
Can you help with the next stages too?
Yes. A suitable project can progress from early layouts into planning, Building Control and construction information rather than being handed between unrelated suppliers.
Free first response
Tell us what you’re planning.
Whether it’s a bigger kitchen, an open-plan downstairs or a wall you’ve pictured coming down for years, send the details here first. We’ll point you at the cleanest next step:
- “Who do I speak to first?”
- “What’s the actual first step?”
- “Does my project need planning permission?”
- “Do I need Building Control?”
- “Which certificates do I end up with at the end?”
- “Who keeps the whole thing compliant?”
Drop a few details below and we'll tell you who should be involved first: designer, engineer, Building Control or builder.
Start here hub page
Not sure which drawings, approvals or builder route you need?
Use the floor plans hub first. It explains whether your home improvement starts with existing/proposed plans, planning drawings, Building Control, structural calculations or a builder quote pack.
See the floor plans and drawing route →Quickest route: send the project details, or call if it is urgent.