Loft Conversions
Loft Conversions in
Bishop's Stortford & Hertfordshire
Velux, dormer and hip-to-gable loft conversions — adding bedrooms, bathrooms and home offices to your existing property without losing the garden.
Overview
More Space Without Losing the Garden
A loft conversion adds usable square footage to a property without taking a single square metre from the garden — and typically returns 15–25% to property value. For growing families and homeworkers across Hertfordshire, it's one of the highest-value projects you can commission.
We deliver three core conversion types: Velux conversions (using existing roof space with new rooflights), dormer conversions (adding a box dormer to gain headroom and floor area), and hip-to-gable conversions (squaring off a hipped end to dramatically increase usable space). The right choice depends on your roof shape, your headroom, and your budget — we'll talk through all three on the first visit.
Why It Matters
Why Cheap Loft Conversions End Up Costing More
Loft conversions live or die on three structural details: the floor (existing ceiling joists are almost never strong enough — proper engineered floor joists are needed), the staircase (must meet Part K of the Building Regs and not eat half the room below), and the head height (1.9m minimum at the head of the stairs is non-negotiable for Building Regs sign-off).
Cheap conversions skimp on one or all three. The result is a "useable" space that sags, an unsigned-off conversion that creates problems on resale, or a staircase position that destroys the room beneath. We design to Building Regs from the first sketch — never bolt them on later.
Our Process
How We Deliver Loft Conversions
Feasibility Survey
We measure existing head height, assess roof structure, and confirm what conversion type your property can actually take.
Site Measure & Quote
Detailed site measure, scope agreed in writing, fixed itemised quote covering everything we'll do.
Programme & Materials
Build programme agreed, materials specified and ordered, lead-in dates locked in before we start on site.
Build
8–12 weeks of fully managed build — joists, dormer (if applicable), insulation, plasterboard, staircase, plumbing, electrics, finishes.
Handover & Guarantee
Building Control sign-off, snagging, written guarantee, and a fully usable new room.
Benefits
What You Get with J&Co
Adds 15–25% to Value
Typical Hertfordshire return on a well-executed loft conversion.
Building Regs Compliant
Designed to Part K, B and L from day one — full Building Control sign-off.
All Trades Coordinated
Carpenters, roofers, plasterers, electricians, plumbers managed in-house.
Workmanship Guarantee
Workmanship cover on every loft conversion — terms confirmed on your quote.
Technical Detail
Velux vs Dormer vs Hip-to-Gable — Which One?
Velux (rooflight) conversions are the cheapest and least intrusive. The existing roof structure stays as-is and Velux rooflights are added to bring in light. Works only if you already have sufficient head height — typically only suited to traditional cut-roof houses with steep pitches. Ideal for converting an existing usable loft into a properly habitable room.
Dormer conversions are the most common. A box dormer is added to the rear of the roof, dramatically increasing head height and usable floor area within the new space. Usually allows a double bedroom plus en-suite within the converted space. Often achievable under permitted development rights, depending on cubic volume rules.
Hip-to-gable conversions apply to semi-detached and detached houses with a hipped roof end. The hip is "squared off" to create a vertical gable wall, massively increasing the usable internal volume. Often combined with a dormer on the rear for the maximum possible space gain. Almost always needs full planning permission.
Many of our clients combine a loft conversion with a rear extension to maximise both ground-floor and first-floor space in one programme — usually saves on scaffold and management costs.
Honest Pricing
How Much Does a Loft Conversion Cost in Hertfordshire?
2026 guide ranges below — every conversion quoted individually after a feasibility survey.
Velux conversion
£35,000–£55,000
Minimal structural change, new rooflights, new staircase, full insulation and finish.
Dormer conversion
£50,000–£75,000
Box dormer added, full new floor structure, staircase, en-suite typically included.
Hip-to-gable + dormer
£70,000–£110,000+
Maximum space gain, full planning required, structural reconfiguration.
What affects the price
- Conversion type (Velux / dormer / hip-to-gable)
- Inclusion of en-suite
- Staircase position and complexity
- Existing roof structure (cut roof vs trussed)
- Insulation and finish specification
- Planning vs permitted development route
Service Area
Areas We Cover for Loft Conversions
We deliver this service across our full Hertfordshire and Essex catchment. Regular projects in Bishop's Stortford, Sawbridgeworth, Harlow, Saffron Walden, Stansted Mountfitchet, Great Dunmow, Epping, Ware, Hoddesdon, Broxbourne, Cheshunt, Welwyn Garden City and Stevenage.
Outside this list? Call us with your postcode — we frequently work the wider London fringe and across the rest of Hertfordshire.
FAQs
Loft Conversions — Frequently Asked Questions
Get a Free Loft Conversion Quote
Feasibility survey, fixed itemised quote, fully managed build. Across Hertfordshire and Essex.
Page last updated: May 2026 · J&Co Builders Ltd · 1 Ugley Hall Cottages, Bishop's Stortford CM22 6JB