Loft Conversions in Biggleswade & Across Bedfordshire

JLS Building & Property Development is a family-run construction company based in Biggleswade with over 30 years of experience. We design and build loft conversions across Bedfordshire, Hertfordshire and Cambridgeshire, managing everything from structural calculations and building regulations through to plastering, carpentry and final decoration.

 Dormer Loft Conversions

The most popular choice locally. A dormer extends out from the roof slope to create full head height and usable floor space, ideal for the 1930s semis and Victorian terraces found across Biggleswade, Sandy and Hitchin. Flat-roof dormers maximise space; pitched dormers keep a more traditional look for conservation-sensitive streets.

Hip-to-Gable Conversions

Common on semi-detached and end-of-terrace homes where the roof slopes on the side. We build the hip up into a vertical gable wall, dramatically increasing loft volume. Often combined with a rear dormer for the largest possible conversion.

Velux / Rooflight Conversions

The most cost-effective option. If your loft already has generous head height, we install structural flooring, insulation, a staircase and Velux windows without altering the roofline, and usually no planning application is required.

Full Mansard and Bespoke Conversions

For maximum space, or for properties with unusual rooflines, we design bespoke solutions with our structural engineers.

• Structural design and calculations, coordinated with building control

• Steelwork and structural flooring

• Staircase design and installation, see our carpentry and joinery work

• Insulation to current building regulations

• Windows, dormers and roofing

• First and second fix electrics and plumbing (heating, en-suites)

• Plastering, decoration and fitted storage if required

One team, one point of contact, fully project managed from start to finish. We're accredited by the Federation of Master Builders and SafeContractor.

  Most loft conversions in Bedfordshire fall under permitted development, meaning no planning application is needed, but there are limits on volume (40m³ for terraces, 50m³ for semis and detached homes) and rules about dormers facing the highway. Homes in conservation areas, such as parts of central Hitchin and Letchworth Garden City's heritage-controlled streets, need more care. We check this for you at quotation stage and handle any applications required. Building regulations approval is always required, and we manage that process on every project.

We're based in Biggleswade and most of our loft work happens within a 30-minute drive of the town. We regularly convert lofts forhomeowners in Biggleswade, where the mix of Victorian terraces near the town centre and newer homes at developments like Kings Reach both convert well. Over the county border we work for homeowners in Hitchin and Letchworth Garden City  where roof alterations often need a more sensitive design approach, something our team handles routinely.

A typical Velux conversion takes 4–5 weeks; a dormer conversion 6–8 weeks; hip-to-gable projects 8–10 weeks. Because most of the structural work happens from outside via scaffolding, you can normally live in the house throughout, with internal disruption limited to the final stair installation.

Many clients pair a loft conversion with other structural work while the team is on site. See our structural alterations service or, if you're weighing up a loft against building outwards, our house extensions page.

The three decisions that make or break a loft conversion happen before a single tile comes off the roof.

The staircase is the hardest puzzle. Building regulations require 1.9m of headroom over the stairs (2m at the centre), and the new flight has to land somewhere on the floor below without swallowing a bedroom. The best solution is usually stacking the new stairs directly above the existing flight; where that's not possible, we'll show you the options and what each costs you in space before you commit. Getting this wrong is the most common regret we hear from people who used less experienced firms.

Head height determines what type of conversion you need, and sometimes whether the money is better spent elsewhere. If your ridge height is marginal, a dormer recovers usable space; if it's genuinely too low, we'll tell you straight rather than build you a room you can't stand up in. That honesty costs us the occasional job and wins us most of our referrals.

Light and ventilationtransform how the space feels. Velux windows on the rear slope, a glazed dormer face, or a Juliet balcony on gable-end conversions all bring in dramatically more light than people expect from a loft. We position windows for the view and the sun path, not just where they're easiest to fit, and we always include opening windows sized for fire escape compliance where the regulations require them.

We resolve all three in the survey and design stage, so the quotation you approve reflects the loft you'll actually get.