Residential builders since 2008
We build house extensions, loft conversions and full refurbishments across London, Essex, Hertfordshire and the South East. One team from the first drawing to the final snag — with a fixed price and a fixed programme before a single brick moves.
What we build
We are a building contractor, not a management company. The people who price your job are the people who run it, and the trades on site are ours or ones we have used for years.
Single and double-storey rear extensions, side returns and wrap-arounds. We handle the structural design, the building control sign-off and the build itself, so there is one company answerable for the result.
The room most extensions are really built for. We sequence the shell, the glazing and the kitchen fit-out as one programme, which is what stops the six-week gap between a finished slab and a working kitchen.
Dormer, hip-to-gable and mansard conversions that add a genuine bedroom and bathroom rather than a cupboard with a window. Fire regulations and escape routes designed in from day one.
Full refurbishment of period and post-war homes: rewires, replumbs, new heating, damp and structural repair, joinery and decoration. Sensitive to what is worth keeping and honest about what is not.
Not sure which of these your project is? Send us the details and we will tell you straight.
Recent work
Every project below was delivered by our own site team. Scope and duration are as built, not as first quoted.
Walthamstow, E17
A closed-in galley kitchen opened into a single 42m² room. Steel-framed glazing across the full rear elevation, a flush threshold to the garden, and a structural opening formed without temporary works encroaching on the neighbour.
Leytonstone, E11
A Victorian semi given a two-storey side return in standing-seam zinc, deliberately reading as new work against the original stock brick. Added a fourth bedroom and a family bathroom without losing the garden.
Chingford, E4
A 1930s house taken back to brick and studwork. New consumer unit and circuits throughout, a pressurised hot water system, three new bathrooms and restored original doors and architraves.
How we work
Most of what goes wrong on a domestic build goes wrong before anyone picks up a trowel — an unpriced item, a missed approval, a programme nobody wrote down. This is the order we do things in, and it is the same on every job.
We come out, measure up and tell you what is actually possible on your house — including the version you have not thought of, and the version that is not worth the money.
Free · usually within 5 working days
Our architectural and structural partners produce the drawings and calculations. We submit for planning or a lawful development certificate, and handle building control and party wall notices.
Typically 8–12 weeks for approvals
A line-by-line quotation against the approved drawings, with a written programme and a payment schedule tied to stages. No provisional sums hiding the parts nobody has priced.
Fixed price · valid 90 days
One site manager, a fixed start date and a weekly written update. At the end you get the building control completion certificate, all appliance guarantees and a snagging visit at six weeks.
10 year structural warranty
About Dome Helmet
Dome Helmet Ltd has been building in and around London since 2008. We stayed deliberately small: enough people to run three or four sites properly, not enough to need a layer of managers between you and the person laying the bricks.
Every job gets one site manager who is on site daily, a written weekly update, and a programme you can hold us to. We carry £5m public liability and £10m contractors' all-risks cover, and every completed structure is covered by a ten-year insurance-backed warranty.
Accredited by
Get in touch
Send us what you have — a sketch, a set of drawings, or just an idea and a postcode. We will come back within one working day and tell you honestly whether it is something we should be quoting for.