Terraced House Loft Conversion

Terraced houses, especially the Victorian and Edwardian terraces found across large parts of London, come with their own particular set of considerations for a loft conversion. Because the house shares a wall with a neighbour on both sides, any loft conversion here will usually need a party wall agreement with two separate households rather than just one, and that needs to be factored into the timeline from the start.

Many of these terraces have what is often called a London roof, sometimes described as a butterfly roof, which sits low and flat between two party walls. This roof shape often suits a mansard conversion particularly well, since a mansard is designed to work with exactly this kind of roof and can deliver a genuinely large amount of extra space. Dormer conversions are also common on terraces, depending on the exact roof shape and the amount of space the homeowner is after.

Who this for

Victorian and Edwardian terraced houses are the main property type this applies to, particularly those with the low, flat London roof style common across many parts of London. Homeowners in these properties should expect party wall matters with two neighbours rather than one, and should plan their timeline with that in mind.

Terraced House Loft Conversion Cost

Since terraced houses can suit several different conversion types, cost varies more here than for many other categories on this site. Across the UK, terraced house loft conversions generally run from £20,000 to £75,000, working out at roughly £1,150 to £2,500 per square metre, though which end of that range you land on depends heavily on which option, dormer or mansard, ends up being right for your roof. A velux only conversion, where enough head height already exists without altering the roof shape, is the cheapest option at around £15,000 to £25,000, though as covered elsewhere on this site, many London terraces do not have quite enough natural head height for this to work well on its own. A standard rear dormer of around 30 square metres typically costs £30,000 to £50,000. Where a second dormer is added over a rear addition, sometimes called an L shaped conversion, costs rise to somewhere between £55,000 and £90,000. A full mansard, which this page already explains suits the low, flat London roof so well, generally runs from £40,000 to £75,000. London and the South East sit 20 to 40 percent above these UK wide figures, and for a rear dormer on a terraced house in an inner London borough specifically, £65,000 to £90,000 is a more realistic figure than the national average. It is also worth budgeting for costs beyond the build itself, planning and building regulations fees, and the party wall payments this page already covers for both neighbouring households. These add up separately from the construction cost and are easy to forget when comparing quotes. As always, the only way to know your real number is a survey of your specific roof and a proper quote. Get in touch for a free survey.

Project Process Steps