Written by Mark Reid,
Trades Editor ·Verified 12 September 2026
Hemel Hempstead's mix of housing keeps its builders busy with all sorts. You've got the New Town estates around Adeyfield and Bennetts End with their post-war concrete and timber-frame construction, Victorian terraces near the Old Town that often need underpinning or damp work sorted before anything else can happen, and newer developments around Hemel Hempstead Station and Maylands where loft conversions and rear extensions are the usual ask. Properties on the clay soils common in this part of Hertfordshire can be prone to subsidence, so local builders often deal with foundation repairs alongside the more everyday work like re-roofing, garage conversions and kitchen extensions. Anyone extending toward the Chilterns edge, out towards Bovingdon or Chipperfield, might also be dealing with conservation area rules that affect what materials and designs planning will allow.
The businesses listed here were pulled from public business listings and ranked mainly by review rating and how many reviews they've built up, with a small boost given to those showing a working website and phone number. We then checked each one's homepage to confirm building work is genuinely what they do day to day, which keeps electricians, decorators and other unrelated trades off this particular page. Any listing flagged as permanently closed gets stripped out automatically, so what you're seeing should reflect businesses still trading. Where you spot a Trust Verified badge, that business has gone further and passed our full verification, covering trade qualifications and accreditations, public liability insurance, trading history, customer review history and registered company information. Our How We Verify page sets out exactly what that involves. For everyone else on this page, those checks haven't been done by us, so it's worth doing your own homework before you commit to anything.
Before signing off on a builder, ask to see their public liability insurance certificate and check what it actually covers, particularly if scaffolding or structural work is involved. Get written quotes from at least two or three firms, itemised rather than a single lump sum, so you can compare labour, materials and any provisional sums separately. Ask about their approach to building control sign-off for anything structural, an extension, a loft conversion or knocking through a wall, since skipping this can cause real problems when you come to sell. A written contract covering start dates, payment stages and what happens with variations is standard practice and any builder used to bigger jobs should have no issue providing one. Talking to a previous customer or two, even just by phone, tells you more than any number of online reviews.
How We Select & Rate The Best Builders in Hemel Hempstead
Ranking is driven mainly by review rating and review count pulled from public business listings, with a small lift given to businesses showing a working website and phone number. We check each business's homepage to confirm building work is what they primarily do, which keeps unrelated trades off this page. Listings flagged as permanently closed are removed automatically. Businesses marked Trust Verified have additionally passed our full verification, covering trade qualifications and accreditations, public liability insurance, trading history, customer review history and registered company information; see our How We Verify page for the full list. Other businesses here haven't been independently verified by us, and appearing on this page isn't an endorsement. Always do your own checks before hiring.
Recommended and Featured listings are paid placements, so a business's fee affects whether and where it appears. Every other listing is ranked on rating and review count from third-party business listings. How we rank & verify →
A typical enquiry starts with an extension, loft conversion or a kitchen that needs opening up, often after previous quotes have fallen through elsewhere. Dacorum Builders Ltd takes on the groundwork, structural changes and finishing in one continuous project rather than handing off between trades. Based in Hemel Hempstead, the firm holds a 5 star rating from 32 reviews.
Eco-Renovation UK focuses on retrofitting older Hemel Hempstead properties with insulation, glazing and heating upgrades designed to cut energy loss rather than just refresh appearances. Work is typically carried out alongside structural repairs, so clients get both efficiency improvements and general building maintenance in one project. The firm holds a five-star rating from 22 reviews.
Hemel Hempstead's residential streets provide much of the workload for Premier Build Developments, which takes on extensions, renovations and general building projects across the town. Twenty Google reviews have left it with a full five-star average, suggesting consistency across varied jobs. Enquiries can be made through its website for those planning building work locally.
Extensions and loft conversions make up much of the workload at Canko Construction Ltd, based in Hemel Hempstead. The firm has built a small but consistent client base, reflected in a 5-star average across ten Google reviews. Groundwork through to finishing is handled without subcontracting out the core build.
Loft conversions and house extensions form the core of Grand Developments & Construction Ltd's work in Hemel Hempstead, covering everything from initial groundworks through to plastering and finishing. The firm holds a 4.7 rating from 14 reviews, reflecting consistency across multi-stage residential projects rather than one-off repairs.
A 4.7 rating from a dozen reviews points to consistent workmanship at London Construction Company Ltd, based in Hemel Hempstead. The firm takes on building projects across the town, with feedback suggesting reliability rather than one-off satisfaction. Details of specific work can be found via the company's website.
A typical enquiry starts with an extension, loft conversion or a knocked-through kitchen that needs proper structural work rather than a quick patch-up. S Johnson & Sons Builders takes on these larger residential jobs around Hemel Hempstead, managing the build from foundations to finish. Seven reviews on Google have all rated the work five stars.
A 4.9 rating from clients in Hemel Hempstead reflects the standard D. Waldron Brickwork and Building Services LTD holds itself to on brickwork and general building projects. The firm handles jobs ranging from repairs to larger construction work, with feedback pointing to consistency across the smaller sample of reviews. Enquiries can be made through its website.
Home extensions, property refurbishment, and building restoration are the core services offered by Circle Construction Ltd, operating out of Hemel Hempstead. The firm holds a five-star Google rating across its reviews. Circle Construction covers residential and restoration work across the HP2 area and surrounding parts of Hertfordshire.
ASM Construction Ltd works as a building contractor in Hemel Hempstead, covering extensions, renovations and general construction work. The firm has built a small but consistent reputation locally, holding a five-star rating from six reviews. Enquiries can be made through its website for those planning building projects in the area.
CPPC Building Contractors works across Hemel Hempstead, taking on extensions, renovations and general building work for domestic clients. The firm holds a full five-star record from its reviews so far, reflecting consistency in how projects are managed and completed. Enquiries typically cover both structural work and finishing details on existing properties.
Constructing Better Homes Ltd tends to work on extensions and renovations for older properties around Hemel Hempstead, where existing structures often need careful assessment before new work begins. The firm has built a small track record locally, reflected in five reviews rating it five out of five. Projects are handled from initial planning through to completion.
Families across Hemel Hempstead needing extensions, renovations or general building work call on A.R Johnson to see projects through from planning to finish. Based in the HP3 area, the firm takes on domestic jobs of varying scale, working directly with households rather than large-scale developers.
Transparency notice: Recommended and Featured listings are paid placements, so a business's fee affects whether and where it appears. All other listings are ranked by a combined score drawn from ratings and review counts published on third-party business listings, plus basic completeness signals such as a working website and phone. A Trust Verified badge means we have independently checked that business's documents; businesses without it have not been independently verified by us. How we verify →
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A single-storey rear extension typically runs from around £1,800 to £2,400 per square metre depending on finish, so a modest 15 square metre extension might land somewhere between £27,000 and £40,000 once you include fittings. A loft conversion with a dormer usually costs between £35,000 and £55,000 locally, while smaller jobs like a garage conversion often sit between £8,000 and £15,000. Prices swing a lot depending on access, whether structural steels are needed, and current material costs, so getting two or three written quotes for anything beyond a small repair job is the sensible way to check you're not overpaying.
Do I need planning permission for an extension in Hemel Hempstead?
Many single-storey rear extensions fall under permitted development rights and don't need full planning permission, but there are limits on size and height, and these are tighter if your property is in a conservation area such as parts of the Old Town or near Piccotts End. Dacorum Borough Council handles applications and can confirm whether your project needs consent or a lawful development certificate. It's worth checking before any building work starts, since unauthorised work can cause headaches later, particularly if you plan to sell.
How long does a typical extension or loft conversion take?
A single-storey extension usually takes between eight and twelve weeks from breaking ground to a usable space, though weather and any groundworks complications on clay soil can add time. A loft conversion generally takes six to eight weeks once building control has signed off the design. Bigger projects involving structural steels, new drainage or a full rewire will run longer, so ask your builder for a realistic week-by-week schedule rather than just a finish date.
Should I use a local builder or a national company?
A local builder based around Hemel Hempstead or nearby towns like Berkhamsted or Tring will usually know the area's soil conditions, common planning quirks and local building control officers, which can smooth things along. They're also easier to visit mid-project and to chase if snagging issues crop up afterwards. National firms sometimes offer more standardised pricing, but for anything involving Hertfordshire clay or older property foundations, local experience tends to matter more than a national name.
What certificates or paperwork should I ask for before work starts?
Ask for a copy of their public liability insurance certificate and check the cover amount is enough for the job's scale. For structural work, request confirmation they'll handle building control notification and get you the completion certificate afterwards, since you'll need this if you sell the property. If gas or electrical work is involved, ask which registered subcontractors they use and get those certificates too. A written contract with payment stages, a rough timeline and what happens if extra work is found should also be standard.
How do I choose between builders on a list like this one?
Start by reading a spread of recent reviews rather than just the star rating, since a pattern of complaints about missed deadlines or poor communication tells you more than a single bad review. Ask each builder for two or three references from jobs similar in size to yours, and actually ring them. Check their public liability insurance certificate yourself and confirm it's current, and ask directly whether they hold any trade accreditations relevant to your job. If a business carries our Trust Verified badge, that means it's passed additional checks on our end covering qualifications, insurance, trading history and company records, but for anyone without that badge, doing these checks yourself before signing anything is the safer approach.
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