Larger Home Extension Solihull: Prior Approval, Costs, 42-Day Timeline and How to Get It Right
Most homeowners hit the same wall. You want a 6m kitchen extension at the back, your neighbour mentions planning permission, and suddenly you're lost in a maze of rules about permitted development, prior approval, and consultation periods.
Here's what actually matters. The Larger Home Extension route lets you build deeper rear extensions in Solihull, up to 6m for semis and terraces and 8m for detached houses, without a householder planning application. The process runs on a 21-day neighbour consultation and a 42-day council decision window. The fee is £240 plus the Planning Portal service charge.
But extending deeper isn't automatic. The council still assesses the impact on your neighbours, what planners call amenity, and if you get the design wrong or ignore the local rules, you'll face objections or refusal.
This guide explains the Solihull process, what the council actually looks at, realistic build costs, and the mistakes that trip people up.
Eligibility quick check
Rear extension only, single storey
Over 3m up to 6m for semis/terraces, over 4m up to 8m for detached
Not in a conservation area or other designated land
No Article 4 or past conditions removing PD rights
Max height 4m, eaves 3m within 2m of boundary, garden coverage under 50%
Measured from the original rear wall
What counts as a Larger Home Extension
This prior approval route applies to single-storey rear extensions that go beyond the standard permitted development depth. The limits are strict: over 3m and up to 6m for semis and terraces, and over 4m and up to 8m for detached houses, measured from your original rear wall, not later additions.
Other Class A limits apply: maximum height 4m, eaves 3m if within 2m of a boundary, materials similar to the house, and total outbuildings plus extensions covering less than 50% of the garden. Measurements are from the original rear wall, not later additions.
One critical exclusion: this route does not work in conservation areas. Check Solihull's conservation area list before you start. If you're in Knowle, Olton, or Hampton-in-Arden, use a Householder application instead. The same applies if your property has had permitted development rights removed by a previous planning condition, which is common on some estates in Solihull.
Why this route exists
The Larger Home Extension scheme was introduced to let homeowners build deeper rear extensions while giving neighbours a formal say. You notify Solihull Council, they consult adjoining owners for 21 days, and the council decides within 42 days whether prior approval is needed, granted, refused, or not required.
The council's job is to judge one thing: impact on neighbour amenity. That means daylight, sunlight, outlook, and overbearing effect. Design quality, materials choice, and how the extension looks from the street are not part of this assessment. If you want flexibility on those fronts, or you're planning a wrap-around extension that goes down the side as well as the back, you'll need a Householder application instead.
Common mistakes that cause problems
Assuming 6m is automatic
Depth limits are fixed, but approval isn't. If your design overshadows a neighbour's kitchen or blocks their garden outlook, the council can refuse prior approval even if you're within the 6m limit.
Ignoring the 45-degree rule
Solihull applies a 45-degree guide when judging light and outlook, published in the House Extension Guidelines SPD. Staying within it reduces risk during the 21-day consultation. For single-storey rear extensions, if your proposal breaches the 45-degree line from a neighbour's main window, the risk goes up. It's one of several cues officers use to assess amenity.
Starting before Building Regulations approval
Planning permission and Building Regulations are different things. Most extensions need both. Prior approval deals with planning. You still need a separate Building Regulations application for structure, insulation, drainage, and fire safety.
Confusing council letters with Party Wall notices
The council's 21-day consultation letters are planning notices. They don't authorise work to shared walls. The Party Wall Act 1996 is separate and triggers when you're building on a boundary or excavating within 3m or 6m of a neighbour's foundations to a deeper level. Serve Party Wall notices once structural depths are confirmed. Allow 6 to 8 weeks for an award on a straightforward case, so it doesn't stall your start date.
Missing the conservation area exclusion
This prior approval route does not apply on designated land. If you're in a conservation area, you need a Householder application and should expect tighter design control.
The Solihull process and timeline
Step 1: Prepare drawings and details
You'll need plans and elevations that show depth, heights, materials, and boundary distances. The Planning Portal expects a 1:1250 location plan, a 1:500 block plan with boundary measurements, existing and proposed plans and elevations with dimensions, a roof plan if you're using a flat roof or rooflights, a materials schedule, and a list of adjoining addresses for the consultation.
Step 2: Submit through the Planning Portal
Submit "Prior Approval: Larger Home Extension" online with the correct fee. Planning fee £240. Planning Portal service charge £70.83 plus VAT. The planning fee itself is not VATable, the Portal charge is, which is why the total is roughly £325.
Step 3: Neighbour consultation for 21 days
Solihull notifies adjoining owners and invites comments. This is where most objections surface, usually about overshadowing, loss of light, or overbearing impact.
Step 4: Decision by day 42
The council must decide within 42 days of validation. If no decision is issued by day 42, the GPDO allows development to proceed provided all conditions are met. You must obtain written confirmation before you start. Most lenders and insurers want proof.
Step 5: Building Regulations approval
Separate track. You need Building Regulations approval for the build, regardless of the planning route. Submit drawings, structural calculations, drainage details, and insulation specs to Building Control.
Local examples: Shirley and Hall Green, Solihull
Shirley success: A 1930s semi on Bills Lane wanted a 6m kitchen-diner with utility. The owners were within the depth limit but concerned about the neighbour to the north, whose kitchen window faced the proposed extension.
We prepared plans showing a 3m eaves line near the boundary and matched the existing brick. We submitted prior approval with a sunlight sketch and boundary sections that demonstrated the 45-degree check. Two neighbours commented about potential overshadowing. The case officer assessed amenity impact and confirmed prior approval within the 42-day window.
Building Regulations followed for structure, insulation, and drainage. The entire process from submission to approval took 38 days. This route saved time compared with a full Householder application and kept the build programme moving.
Why it worked: depth within the 6m limit, eaves controlled near the boundary to reduce overbearing effect, and a clear note on overshadowing risk upfront, which is exactly what the council assesses under this scheme.
Hall Green refusal then approval: A Hall Green semi proposed 6m depth. North-facing neighbour kitchen failed the 45-degree test by 10 degrees. Officer refused on amenity. We cut depth to 5.2m and lowered eaves to 2.8m near the boundary. Prior approval granted at resubmission, 28 days.
Costs to build in 2025
Guide ranges for single-storey shells in the West Midlands sit around £1,800 to £3,300 per square metre before VAT and upgrades. A 25m² kitchen-diner often totals £45,000 to £82,500 before VAT, plus kitchen fit-out and glazing.
What drives the range: ground conditions, drainage work, structural complexity, and glazing specification. If you're on clay, expect deeper foundations. If you're connecting to a combined sewer that runs under the extension footprint, expect a build-over agreement and potential drainage diversion costs. High-spec bifolding doors or sliding systems add £8,000 to £15,000, depending on width and specification.
Typical add-ons to budget for: structural engineer fees (£800 to £1,500), Building Control fees (around £600 for a small extension), drainage build-over agreements if applicable, and Party Wall surveyor fees if you're building on or near a boundary (£1,200 to £2,500 for a straightforward award).
Fees in 2025 and how they compare
Larger Home Extension prior approval: £240 application fee. Planning Portal service charge £70.83 plus VAT applies to online submissions over £100. Total around £325 including VAT.
Householder application: £528 for a typical Householder extension after the April 2025 fee changes.
Quick comparison
Larger Home Extension prior approval
Scope: Rear only, single storey, to 6m/8m
Decision time: 42 days
Council fee: £240
What is assessed: Neighbour amenity within PD limits
Householder application
Scope: Any domestic extension not PD
Decision time: 8 weeks target
Council fee: £528
What is assessed: Design and policy against the local plan
Fees correct at publication and subject to national change.
Fees correct at publication and subject to national change.
Your options, costs, and risks
Option A: Larger Home Extension prior approval
Best for straight rear extensions to 6m or 8m where amenity impact is modest.
Pros: Fast, rules-based, £240 fee, 42-day decision window.
Cons: Amenity test still applies. No wrap-arounds. This route only works for rear extensions, not side returns or L-shaped layouts.
Risks: Neighbour objections, permitted development rights removed on some estates, conservation area exclusions.
Suits: Depth-led kitchen-diner projects where you're confident about neighbour impact.
Option B: Householder planning application
Needed for wrap-arounds, conservation areas, or bespoke roof forms.
Pros: Wider design scope, full policy assessment, and works in conservation areas.
Cons: Slower, £528 fee, more drawings required upfront.
Suits: Complex sites, conservation areas, or projects where you need design flexibility.
Option C: Standard permitted development to 3m or 4m with Lawful Development Certificate
Keep within the standard permitted development depth and secure a certificate for resale confidence.
Pros: Predictable if designed precisely, no neighbour consultation required.
Cons: Less space than the Larger Home Extension route. You're limited to 3m for semis and terraces, 4m for detached houses.
Risks and constraints to expect
Designated land: Conservation areas are excluded from this prior approval route. Check whether your property is in Knowle, Olton, Hampton-in-Arden, or another designated area before you start.
Rights withdrawn: Some estates have permitted development removed by conditions on past permissions. Check your property history with Solihull's planning records.
Amenity tests: Depth alone doesn't guarantee approval. Officers judge neighbour impact during the 42-day process. If your design overshadows a kitchen or dining room window, expect objections or refusal.
Regulatory mix-ups: Planning permission and Building Regulations are different systems. You probably need both.
FAQs
How long does prior approval take in Solihull?
Forty-two days from validation, with a 21-day neighbour consultation running within that period.
Can I start if there's no decision by day 42?
The GPDO allows you to proceed if the council is silent after day 42 and all conditions are met. Get written confirmation to avoid risk with lenders or insurers.
What is the fee for Larger Home Extensions?
£240 application fee in England, plus the Planning Portal service charge on online applications over £100. Total around £325 including VAT.
Do I still need Building Regulations?
Yes. Most extensions need Building Regulations approval regardless of the planning route.
Do conservation areas qualify?
No. Use a Householder application and expect tighter design control on materials, fenestration, and roof form.
What should I budget to build?
A realistic guide is £1,800 to £3,300 per square metre before VAT and fit-out. Add structural engineer, Building Control, drainage, and Party Wall costs on top.
See it clearly, decide confidently
We design to the exact rules on your street, model your options in 3D to show what works and what triggers objections, and handle the prior approval submission and neighbour consultation process for you. We also coordinate Building Regulations approval and your structural engineer, so the build runs smoothly.
Most families in Solihull underestimate the amenity test or miss the Party Wall timing. We flag those risks upfront and design around them. Book a short call for projects in Solihull, Shirley, Knowle, and Olton.
Author: Mark McTernan
McTernan Design, Solihull
Tel: 07955 572811 | mark@mcternandesign.co.uk | YouTube channel
