A two storey rear extension is one of the most transformative projects available to Teesside homeowners — extending the rear of the house on both ground and first floor simultaneously, typically adding a kitchen-diner and new bedroom or bathroom in a single build. The economics are compelling: because the foundations, structural frame, and roof are shared across two floors, you gain significantly more floor area per pound spent compared to separate single storey projects.

Unlike two storey side extensions — which always require planning permission — two storey rear extensions can sometimes be built under Permitted Development, avoiding the need for a planning application entirely. However, the rules are strict and the key measurements (depth and garden length) catch many homeowners out. We check your property’s eligibility during your free consultation, before any drawings are started.

Planning rules

Do you need planning permission for a two storey rear extension?

 The 7 metre boundary rule — the one that catches most Teesside homeowners

This is the single most common reason a two storey rear extension in Teesside cannot use Permitted Development. Many semi-detached and terraced houses in Middlesbrough, Stockton, and surrounding areas have rear gardens between 8 and 12 metres long — which sounds ample, but the maths catches people out.

The answer depends on your garden depth, proposed extension depth, and property location. Here’s exactly how the rules work in 2026 — and the one measurement that catches most Teesside homeowners out.

Add a 3 metre deep two storey extension to a house with a 9 metre garden, and you have only 6 metres remaining to the rear boundary — less than the required 7 metres. In this scenario, a full planning application is required regardless of any other factors. We measure your garden and check this calculation during the free consultation, before you commit to anything.

• 10m+garden depth — PD likely possible

• >10mgarden depth — full planning likely needed

✅ If your extension qualifies for Permitted Development

No planning application is needed. You can proceed directly to building regulations and instructing a builder. We strongly recommend obtaining a Lawful Development Certificate (LDC) — a formal document confirming the extension was lawful, which protects you when selling the property and prevents future challenge. We can prepare the LDC application as part of our drawings package.

✅ If a full planning application is required

We manage the entire planning application process as part of your fixed-price drawings package. Two storey rear extensions are regularly approved by Teesside councils — the key is good design that addresses light, privacy, and scale. Our 97% first-time approval rate reflects our knowledge of what local planning officers expect.

What the council considers — and how we address it

How it works

From first call to planning decision

A clear process that starts with your planning position and ends with drawings ready for your builder — with everything in between handled for you.

1 – Free consultation — PD eligibility check and fixed-price quote

We start by working out your planning position. We’ll ask for your approximate garden depth and the depth you’re considering for the extension. Within minutes, we can tell you whether Permitted Development is likely to apply — which determines the route forward and the overall cost and timescale. You receive a fixed-price quote on the call, with no obligation to proceed.

💡 Useful to have to hand: approximate garden length from rear wall to fence, and the size of the extension you have in mind (even a rough idea is fine at this stage).

2 – Site survey — precise measurements of property and garden

We visit your home in Teesside to carry out a full measured survey: both floors of the existing house, all external elevations, and the precise distance from the rear wall to the rear boundary. For two storey rear extensions, accurate measurement of both floors and the garden depth is critical — the 7 metre boundary rule and matching roof height requirements leave no margin for estimation.

3 – Design and drafting — all drawings ready within 10–14 working days

We produce the full drawing set for both floors: ground and first floor existing and proposed plans, all elevations, site and block plans, and the design and access statement where required. We share draft drawings with you for review and sign-off. We pay particular attention to first-floor rear window positions, ridge heights, and the treatment of any side-facing first floor windows — the details that determine whether PD applies and whether a planning application succeeds.

💡 At this stage we also flag anything in the design that could attract a planning objection — such as windows creating overlooking — and propose solutions before submission.

4 – PD route: Lawful Development Certificate (recommended)

If your extension qualifies for Permitted Development, you can legally build without any council application. However, we strongly recommend applying for a Lawful Development Certificate — a formal document proving the extension was lawful, which solicitors and buyers request when you come to sell. We can submit the LDC application on your behalf as part of the same package. LDC decisions typically take 8 weeks and cost £258 in council fees.

5 – Planning route: full application submitted and managed

If a full planning application is needed, we submit via the Planning Portal to your local Teesside council, manage the application fee (reimbursed), and liaise with the planning officer throughout. We monitor the application and respond promptly to any queries — keeping the application moving towards a decision within the 8-week statutory period.

6 – Decision received — your builder has everything they need

We notify you immediately on receipt of the planning decision or LDC. We explain any conditions and advise on next steps. Your builder will need building regulation drawings before work starts on site — these are a separate set of technical drawings which we can quote for alongside your planning package, saving time by running both in parallel.