South Cornwall · TR3
Loft Conversions in Carnon Downs
A well-designed loft conversion adds a bedroom, an en-suite and useful storage to homes that were never built with the upper floor in mind — usually inside permitted development and almost always cheaper per square metre than extending sideways. In Carnon Downs, that work is shaped by the place itself — Carnon Downs is a substantial residential village south of Truro on the A39, with a significant late twentieth-century estate expansion and a popular village school, with a building stock that leans toward 1960s and 1970s estates and modern Persimmon-style estates.
Local context
Why Carnon Downs is its own job.
Outside Conservation Area and AONB but in close proximity to AONB to the south. Feock parish operates active input on edge-of-village sites and infill. For loft conversion specifically, Carnon Downs sits outside the headline designations, which usually gives a slightly more flexible starting point — but parish-level character still matters. That's why we treat every Carnon Downs project as a TR3-area job first — not a generic Cornwall job with a postcode bolted on.
Planning note
Most Cornish loft conversions are permitted development — but a Certificate of Lawfulness is worth the extra week and small fee for resale protection.
What we focus on
Loft Conversions considerations specific to Carnon Downs.
01
Building regs require minimum 2.0 metre headroom over the stairs and 30-minute fire protection on the existing stair enclosure — both shape the design.
02
Cut-roof Cornish properties are easier to convert than modern trussed roofs; the structural strategy varies completely.
03
Permitted development volume allowances are 40 cubic metres on a terrace and 50 on a detached or semi — but rear dormers in Conservation Areas often need full planning.
Our process
How a Carnon Downs loft conversion project runs.
Step 1
Feasibility
Roof, headroom, stair landing and structural assessment.
Step 2
Design
Layout options that respect the staircase, headroom and bathroom positioning.
Step 3
Approvals
Planning or permitted development confirmation, plus building regs.
Step 4
Build
Sequenced to keep the family living downstairs throughout most of the work.
Step 5
Handover
Finish, snag, certify, hand over the keys.
Loft conversions typically run six to eighteen weeks on site depending on type, with four to eight weeks of design and approvals beforehand.
FAQs
Carnon Downs Loft Conversions — common questions.
- How long does a loft conversion take?
- Allow six to ten weeks on site for a Velux conversion, eight to fourteen weeks for a dormer, twelve to eighteen weeks for hip-to-gable. Add four to eight weeks for design and regs beforehand. In Carnon Downs specifically, we'd start by checking the latest parish-level planning history before committing to a direction.
- Will it add value?
- An extra bedroom and bathroom typically adds noticeably more value than the build cost in most Cornish markets — but the value matters less than the daily use you'll get from the space.
- How much does a loft conversion cost?
- A simple Velux conversion starts around £30,000 in Cornwall; a rear dormer with en-suite typically runs £45,000 to £65,000; hip-to-gable and mansards more. Stair location and bathroom complexity drive most of the cost.
- Will I have enough headroom?
- We need a minimum 2.2 metres ridge-to-joist before alterations to make a usable conversion straightforward. Less than that and we'd consider raising the ridge, which is a planning conversation, not a permitted development one.
Other services in Carnon Downs
Nearby places we cover