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House extensions
Single & double-storey extensions that add real space and value — engineered before a brick is laid.
Explore extensionsConsidered extensions, loft conversions and renovations for homes across Slough, Windsor and the surrounding villages — fixed quotes, fully insured, finished beautifully.

Accredited & insured — building you can trust
Building work is a leap of faith. We remove the risk that makes it stressful — in writing, every time.
Every project fully insured and backed by a written workmanship guarantee.
The price we agree is the price you pay. No surprises halfway through.
You pay as work completes — never a large deposit up front.
A Slough team with a local name and reputation to protect.
One local team, one standard of finish — design, build and project management under one roof.
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Single & double-storey extensions that add real space and value — engineered before a brick is laid.
Explore extensions
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Turn dead roof space into a bedroom, office or en-suite.
Explore lofts
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Full design-and-build fits, managed from first drawing to final tile.
Explore fits
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Whole-home refurbishments and structural work that bring tired properties back to life.
Explore renovationsNot sure where to start? Get free, no-obligation advice →
Real projects, completed for real homeowners across Slough and the surrounding area.
A four-month transformation in Langley — fixed price, finished a week early, handed back spotless.
"They quoted a fixed price, stuck to it, and finished a week early. You'd never have known there was building work going on."
"After a bad experience with another builder, Hargreaves restored our faith entirely. Faultless work."
The questions homeowners ask us most — answered honestly, before you ever pick up the phone.
Ask us anythingEvery project is different, but as a guide, single-storey extensions typically start from £30,000 and loft conversions from £35,000. After a free site survey we give you a detailed fixed quote — no guesswork, no hidden extras.
Many extensions and lofts fall under permitted development, but not all. We'll tell you exactly where you stand and handle the drawings, applications and building control on your behalf if needed.
A typical single-storey extension takes 10–14 weeks and a loft conversion 6–8 weeks. We agree a clear timeline before we start and keep you updated at every stage.
You pay in stages as work is completed — never a large deposit up front. Every milestone is agreed in writing before we begin.
We keep the site clean and contained, protect your home throughout, and work to agreed hours. We've completed hundreds of projects in occupied homes and leave it spotless each day.
Yes — fully insured, with a written workmanship guarantee on every project. We're accredited members of the FMB, TrustMark and Checkatrade.

Book a free site survey and get a no-obligation written quote. No pressure, no jargon — just honest advice from a local team.