Getting quotes for a loft conversion is where many homeowners start to feel out of their depth. The numbers are large, the scope is technical, and it is easy to compare quotes that are not actually covering the same work. A low quote is not a bargain if it excludes structural engineering, Building Regulations fees, scaffolding, or a staircase.
This guide explains what a complete loft conversion quote must include, what the warning signs look like, and how to run a fair comparison before you commit.
What a Full Loft Conversion Quote Should Include
A properly scoped quote will itemise everything required to take the project from ground level to Completion Certificate. If any of the following are absent, ask explicitly whether they are included or excluded — and get the answer in writing.
Structural and Design Elements
- Structural engineer’s calculations (typically £600–£1,200 for a dormer)
- Architectural drawings for Building Regulations submission
- Building Regulations application fee (typically £400–£700 for a loft)
- Party wall surveyor fees, if applicable (£700–£1,500 per party per wall)
Structural Build
- Temporary weatherproofing during roof opening
- Structural steelwork (typically £1,500–£4,000 for a standard dormer)
- Steel delivery and craneage or manual handling
- New floor structure (156 mm or 200 mm joists, decking)
- Dormer or hip-to-gable framing
- Roof covering (tiles, felt, battens to match existing)
- Dormer cladding (zinc, lead, timber, or render)
- Roof windows or dormer windows, installed and weathertight
Access and Scaffolding
- Scaffold erection, weekly hire, and strike (commonly £2,000–£4,500 for a standard loft)
- Skip hire and waste removal
First and Second Fix
- Staircase supply and installation (typically £2,000–£5,000)
- Insulation (warm roof and floor; 100–150 mm rigid insulation between rafters)
- First-fix carpentry (stud partitions, door linings)
- First-fix electrics (circuits, consumer unit work if needed)
- First-fix plumbing (if bathroom included)
- Plasterboard and skim plastering
- Second-fix electrics (sockets, lighting, extractor)
- Second-fix plumbing and bathroom suite (if included)
- Joinery (skirting, architrave, internal doors)
- Decoration (two coats on walls and ceilings; primer on woodwork)
Items Often Omitted from “Budget” Quotes
- Floor finish (engineered timber, carpet, LVT)
- Loft hatch or loft ladder for any retained storage
- Smoke and heat detection (Building Regulations Part B requires this)
- Fire doors to escape route (Part B — required from loft stair down to ground floor exit)
- Mains-wired smoke alarms on each floor (often omitted from initial scope)
Sample Quote Breakdown: Rear Dormer with En-Suite (London/SE, 2026)
The following illustrates a realistic itemised quote for a typical rear dormer conversion on a 1930s semi-detached house in greater London, adding one bedroom with en-suite shower room.
| Item | Typical range |
|---|---|
| Structural engineer | £700–£1,100 |
| Architectural drawings + Building Regulations | £1,200–£2,000 |
| Building Regulations application fee | £450–£650 |
| Scaffold (erect, hire 10 weeks, strike) | £2,500–£4,000 |
| Temporary weatherproofing | £400–£700 |
| Structural steelwork (supply + install) | £2,000–£3,500 |
| New floor structure | £1,500–£2,500 |
| Dormer frame, roof covering, cladding | £6,000–£10,000 |
| Roof windows or dormer windows | £1,500–£3,000 |
| Staircase (supply + install) | £2,500–£4,500 |
| Insulation | £2,000–£3,500 |
| First and second fix (carpentry, elec, plumbing) | £8,000–£14,000 |
| Bathroom suite + tiling | £3,500–£6,000 |
| Plastering | £2,500–£4,000 |
| Decoration | £2,000–£3,500 |
| Floor finish | £1,200–£2,500 |
| Waste removal | £600–£1,000 |
| Total | £38,550–£66,450 |
A mid-spec project in London would typically come in at £48,000–£56,000 all-in for the scope above. If a quote comes in significantly below £40,000 for a dormer with en-suite in London, something has been excluded.
Red Flags in a Loft Conversion Quote
Vague Lump Sums
“Complete loft conversion — £32,000” tells you nothing about what is and is not included. Any reputable contractor will itemise. If they will not, you have no basis for comparing with other quotes and no protection if items are claimed to be “extras” later.
No Mention of Building Regulations or Structural Engineering
These are not optional — all habitable loft conversions require Building Regulations approval and structural engineer’s calculations. A quote that makes no mention of either is either excluding them (leaving you to source and pay separately) or not accounting for them at all.
Excessive Upfront Payment Request
A reasonable deposit for a loft conversion is 10–20% of the contract value, paid on commencement. Some contractors ask for 25% upfront for material procurement, which can be acceptable if materials are unusual or lead times long. Any request for 30% or more before work starts — or for staged payments that do not correlate to measurable completion milestones — is a risk. Rogue traders in the construction sector routinely request large upfront sums and disappear or slow down dramatically after receipt.
No Specification of Materials
“Tile the dormer” — with what? Zinc? Lead? Tile? Cedral? Specification matters both for cost and building control approval. A quote should state the proposed cladding material and the roofing tile specification.
No Mention of Party Wall
If the loft abuts a party wall (essentially certain on a terraced house and common on semis), the Party Wall etc. Act 1996 requires notice to neighbours before work starts. A contractor who makes no mention of this has either not assessed the project properly or is planning to skip it — both are problems.
Questions to Ask Every Contractor
- Is Building Regulations approval included in your quote, and who submits?
- Who is the structural engineer, and are their calculations included?
- What is your scaffold specification and how long does it include for hire?
- What tile/cladding specification are you pricing for the dormer?
- Does your quote include all fire doors and smoke alarms required under Part B?
- What are your proposed payment stages, and what completion milestone triggers each payment?
- Do you carry public liability insurance of at least £2 million, and are you registered under a competent person scheme (e.g., NAPIT or NICEIC for electrics)?
- Will you provide a written contract before work starts?
How to Compare Quotes Fairly
Lay the quotes side by side and tick off each item in the list above. Where one quote includes something another excludes, adjust the total by adding the missing item’s typical cost. Only compare like-for-like totals.
Do not automatically choose the lowest quote. The difference between a £42,000 quote and a £52,000 quote is often partially explained by items missing from the lower one and partially by genuine differences in contractor overhead or margin. Once you have normalised for scope, the gap usually narrows. If two quotes are genuinely equivalent in scope and one is 15–20% cheaper, ask the cheaper contractor to explain where the saving comes from — the answer will tell you a great deal.
Check references. Ask for the addresses of two or three recently completed loft conversions and view them in person if possible. Ask the homeowners whether the contractor finished on time, how they handled problems, and whether they would use them again.
A written contract — ideally using a standard form such as the JCT Homeowner Contract or a reputable contractor’s own terms — should be in place before any work starts or any money changes hands beyond the deposit.
