Loft conversion cost guide · 2026

How much does a loft conversion cost?
Here are our actual prices.

Most builders make you book a visit to get a number. We publish ours: fixed-price loft conversions from £25,000 + VAT, with every type, extra and finish priced below — and a 60-second calculator if you want a figure for your own home right now.

The short answer

Between £25,000 and £61,600 + VAT for most homes

Three things set the price: the type of conversion your roof allows, whether you add a bathroom, and the finish you want. Property type and size nudge it a little either way. Everything else — structural steel, insulation, stairs, windows, fire safety — is included in every quote.

Get my price in 60 seconds

No email needed to see the number.

Conversion type	Guide price	Best for
Velux / roof-light	from £25,000 + VAT	Best for gable roofs with good head height
Rear dormer Most popular	from £28,000 + VAT	Terraced and semi-detached homes
Hip to gable + Velux	from £32,500 + VAT	Semis and detached homes with hipped roofs
Hip to gable + dormer	from £35,500 + VAT	Hipped-roof semis wanting the most space
L-shaped dormer	from £38,000 + VAT	Victorian and Edwardian terraces with a back addition
Hip to gable + L-shaped dormer	from £45,500 + VAT	Hipped-roof homes with a back addition

Guide prices are for a 3-bed semi-detached house, standard finish, no bathroom. Confirmed in writing after a free survey.

What moves the number

The extras, priced honestly

Adding a bathroom

Basic — shower, basin and WC+£6,200
Standard — the one most people choose+£7,800
Premium — upgraded suite and tiling+£9,600

A loft bedroom with an en-suite is the version that adds the most to a home's value, so most people add one.

Finish

Standard — plastered, wired and ready for you to decorate and lay flooringIncluded
Shell only — structure, roof, stairs and floor in; you do the internal fit-out (insulation, plasterboard, plastering, electrics)−£5,000

Standard is what the guide prices assume. Shell only suits people with their own trades lined up for the inside.

Your house

Semi-detached, 3 bedthe guide price
Terraced−£1,000
Detached+£1,500
Bungalow+£3,000
2 bedrooms or fewer−£1,500
4 bedrooms+£1,500
5+ bedrooms+£3,500

Bigger footprints mean more floor, more insulation and more roof, so the price moves by a fixed amount rather than a percentage.

Fixed means fixed

Why our number doesn't move — and why most quotes do

A general builder prices a loft the way they price everything: an estimate, then variations as the job unfolds. That is where "£30k" becomes "£42k". We only build lofts, so we know exactly what goes into one. After the free survey you get a written, itemised price for the agreed specification, and once it is signed the only thing that changes it is a change you ask for.

Structural steel and calculations includedNot a "subject to engineer" line that arrives later.
Built to Building RegulationsInspected at every stage so you get the completion certificate you need when you sell.
10-year structural guaranteeIn writing, on every conversion.
Not included, so you knowBuilding Control fees, planning fees if your build needs an application, a party wall surveyor if a neighbour's wall is involved, decoration and floor coverings, and furniture.

£25,000+ VAT, from. Every price on this page is real.

Is it worth it?

What a loft conversion adds to your home

The widely cited figure for an extra bedroom and bathroom in the loft is up to 20% of a home's value. On a £400,000 house that is up to £80,000 — against a build that usually costs £30,000 to £45,000. The calculator works this out for your own home value, next to your price.

up to 20%

Typical value added

Bedroom plus bathroom in the loft

Weeks

Not months

Built by a team that only does lofts

£0

To get a price

Calculator, then a free survey

10 yr

Structural guarantee

In writing, every build

Cost questions

The price questions people ask us most

How much does a loft conversion cost in the UK in 2026?

Nationally you will see anything from £25,000 to £75,000 quoted. Our fixed prices start at £25,000 + VAT for a Velux conversion and £28,000 + VAT for a rear dormer, the most popular type. Adding a bathroom is £6,200 to £9,600 on top.

Does the price include VAT?

Prices on this page are shown plus VAT at 20%, which is how loft conversions are quoted across the industry. Your written quote shows both figures.

Is the calculator price the real price?

It is a genuine estimate built from our actual pricing, usually within about 5% of the final figure. The free survey checks head height, structure and access, and then the price is fixed in writing.

What is the cheapest kind of loft conversion?

A Velux (roof-light) conversion, because the roof stays as it is. It suits gable roofs with good head height. A rear dormer costs a little more but gives far more usable floor space, which is why most people choose it.

Do I need planning permission?

Most loft conversions are permitted development, so no planning application is needed. Conversions in conservation areas, listed buildings and flats usually do need one. We tell you at the survey and handle the paperwork if it is needed.

Can I spread the cost?

There is no deposit to book a survey and nothing to pay for a written quote. Ask about the payment schedule at the survey and we will set it out in writing with your price.

How much does a loft conversion cost? Here are our actual prices.