Cost is almost always the first question. Not the design not the timeline not the planning rules — the cost. And unlike a lot of extension builders in Milton Keynes we are happy to give a straight answer before you have even booked a site visit.
Crownhill Building Services has been delivering single storey extensions across MK since 2006. Rear extensions in Bletchley and Westcroft side extensions in Wolverton and Newport Pagnell kitchen extensions in Loughton and Crownhill — nearly two decades of projects across the region and the same team throughout. Here is what you need to know about pricing before you start talking to anyone.
What Affects the Cost of a Single Storey Extension in MK?
No two projects are identical and the cost of a single storey extension in Milton Keynes reflects that. Several factors feed into the final figure.
Size is the most straightforward. We price on a per square metre basis which gives you a clear and predictable starting point from the first conversation. Larger footprint means more materials more labour and more time on site — but the rate per square metre stays consistent.
Ground conditions vary considerably across Milton Keynes. The clay-heavy subsoil common in parts of Loughton and Oldbrook behaves differently to the ground conditions you find in Crownhill or Wavendon Gate. Foundation type — whether conventional concrete strip or screw pile — is determined by what is actually under your garden and affects both cost and programme.
Specification and finish account for a significant portion of the overall budget. Roof type — flat or pitched — door and window choice bifold or sliding internal plastering and floor finishes all sit within the scope of your project. If a kitchen installation is part of the brief that comes into the quote too.
Site access is a practical factor that gets overlooked. If the rear of your property is only accessible through the house the logistics of the build change — and that has a knock-on effect on both programme and cost.
How Much Does a Single Storey Extension Cost in Milton Keynes?
Our current rate for single storey rear and side extensions that fall within Permitted Development is from £2,500 per square metre inclusive of VAT. That is a fixed rate — not a starting point that drifts upward through the build. The figure we put in writing before work begins is the figure on the final invoice.
Permitted Development removes the need for a full planning application on most single storey rear and side extensions. No council fees no waiting months for a decision no uncertainty about whether the project can proceed. For the majority of MK homeowners considering a rear or side extension this is the route — and it is one of the reasons single storey extensions remain the most popular choice across the region.
What the Price Includes
Everything from groundwork to finished extension. Architectural drawings and structural engineering. Foundation preparation and groundwork. Structural frame brickwork and roofing. Internal plastering and fit-out. All services connections. And Building Control from initial notice through to final sign-off.
Building Control is the part of the process most homeowners think about least — until something goes wrong. It is the statutory inspection regime that runs throughout the build and confirms that the extension meets building regulations at every stage. We manage all of it directly. Booking inspections chasing sign-offs dealing with queries — none of that lands on the client.
Permitted Development — What It Means in Practice
Most single storey rear extensions in Milton Keynes qualify under Permitted Development provided they stay within defined limits. For a terraced or semi-detached property the extension can project up to 3 metres beyond the rear wall without a planning application — or up to 6 metres through a Prior Approval process which is considerably lighter than full planning.
For detached properties those limits rise to 4 metres under Permitted Development and 8 metres under Prior Approval.
We check your Permitted Development position at no charge during the initial consultation. You get a straight answer — not a vague maybe that leaves you uncertain about whether to proceed.
How We Work Across Milton Keynes
Nearly twenty years of single storey extension projects across MK means we know the region well — the ground conditions the property types the local planning department's requirements and the practical realities of working in established residential streets across Bletchley Westcroft Crownhill Loughton Oldbrook Wolverton Newport Pagnell and Wavendon Gate.
We are a local team. Not a national contractor parachuted in for the day. That means faster site visits more accurate quotes and a build team that understands the specific conditions of your area before work starts.
Guarantees and Insurance
A 12-month parts and labour warranty runs from completion on every project. Public liability cover sits at £2 million throughout the build. All contractors working on your project hold current Gas Safe NICEIC NAPIT Checkatrade and FENSA accreditations — not as a box-ticking exercise but because the work demands qualified people at every stage.
Getting an Accurate Quote for Your Project
The per square metre rate gives you a reliable anchor but the precise cost of your single storey extension in MK depends on the specifics of your plot your brief and your chosen finish. A free site visit is the only way to give you a figure you can actually plan around — and it costs you nothing.
Get in touch today to arrange your free no-obligation consultation. Find out more about how we run our projects or take a look at single storey extensions we have completed across Milton Keynes. If planning permission is still on your mind our guide on Permitted Development for home extensions in Milton Keynes covers everything clearly.