Gable to Gable Loft Conversion
A gable to gable loft conversion is for houses that already have a vertical gable wall at both ends of the roof, rather than a hipped, sloping end on one or both sides. Because the full width of the roof is already there to build across, you can go straight to a full width dormer spanning from one gable wall to the other, without the extra step of straightening a hipped end into a gable first, the way a hip to gable conversion has to.
This is different from a hip to gable conversion, covered elsewhere on this site, which is for houses where one end of the roof slopes inward rather than standing vertical. If your house already has two gable ends, you are starting from a more advanced position, the width is already there, so the whole project is often simpler and less structural work is needed to achieve a similarly large room.
A dormer built gable to gable gives you a flat ceiling and close to full standing height across almost the entire width of the loft, rather than the room narrowing towards either end the way a smaller, centred dormer would. It is one of the most space efficient conversions available on a house with the right roof shape to begin with.
Who this for
This service suits detached and semi detached houses, and some end of terrace properties, that already have a gable wall at each end of the roof rather than a hipped roof shape. It particularly suits homeowners who want the largest possible single room from their loft, since building across the full width tends to give more usable floor space than a narrower dormer on the same roof.
Gable to Gable Loft Conversion Cost
A gable to gable loft conversion, effectively a full width dormer on a roof that already has two gable ends, typically costs £55,000 to £80,000, working out at roughly £2,200 to £3,000 per square metre. This is generally less than a hip to gable conversion combined with a full width dormer, which runs £65,000 to £95,000, since your roof does not need the hip straightened into a gable wall first. London labour rates currently run 30 to 42 percent above the UK average for loft work, and the South East sits around 18 percent above average, so budgeting towards the upper end of these figures makes sense for most homeowners in and around London. A full width dormer project typically takes ten to twelve weeks on site once building work begins. As always, the only way to get an accurate figure is a survey of your specific roof. Get in touch for a free survey and a detailed quote.
Project Process Steps
We survey the roof to confirm both ends are genuine gable walls rather than hipped, since this determines whether a gable to gable approach is available to you without any hip conversion work first.
We design the full width dormer to make the best use of the space between the two gables, working out where windows, headroom and the staircase will sit within the new room.
Our structural engineer designs the beams needed to support the new dormer across the full width of the roof, since removing this much of the original roof slope needs proper load bearing calculations.
Once the structure is built and weathertight, the project moves into the usual interior stages, insulation, plumbing, electrics, staircase and finishing.
Frequently asked questions (FAQ)
What is the difference between gable to gable and hip to gable?
A hip to gable conversion is for a roof where one end slopes inward, and the work involves rebuilding that sloped end as a vertical gable wall before you can build across it. A gable to gable conversion is for a roof that already has a vertical gable wall at both ends, so you can go straight to building a full width dormer without that extra step.
Does a gable to gable conversion need planning permission?
Often not, provided the finished project stays within your permitted development volume allowance, generally fifty cubic metres for a detached or semi detached house. As with any loft conversion, this depends on your specific property and its planning history, so it is worth checking rather than assuming.
Why is a gable to gable conversion sometimes cheaper than hip to gable plus a dormer?
Because the gable walls already exist, you are not paying for the structural work involved in straightening a hipped end into a gable wall first. You go straight to building the dormer across the full width, which usually means less overall structural work for a similarly sized finished room.
Can any house with two gable ends use this option?
Most can, though the exact size and shape of dormer possible still depends on your roof pitch, your permitted development allowance, and whether any previous work has already used part of that allowance. A survey will confirm what your specific roof allows.
How much floor space does a gable to gable conversion typically add?
It varies by house, but because the dormer runs the full width of the roof rather than being set in from either side, it generally creates more usable floor space than a narrower, centred dormer would on a comparable roof.