I quoted on two roofs last week. Same size. Same number of tiles needed. Same general area of London.
One quote: £14,500. The other: £23,000.
The homeowner getting the £23,000 quote was confused. “Why is mine so much more? The house down the road was way cheaper.”
The answer took me twenty minutes to explain. Let me give you the same breakdown.
The Basic Components of Any Roof Quote
Before we get into variables, understand what you’re paying for:
- Materials: Tiles, felt, battens, lead, fixings, insulation
- Labour: Roofers’ time on site
- Access: Scaffolding, permits, equipment
- Waste disposal: Skip hire, tipping fees
- Overheads: Insurance, vehicles, admin, warranty coverage
- Margin: What the company makes on the job
A proper quote should itemise at least some of these. If it just says “roof replacement: £15,000,” you don’t actually know what you’re getting.
Factor #1: Roof Size (Obviously)
Let’s state the obvious: bigger roofs cost more.
But size isn’t just square metres—it’s complexity.
A simple rectangular bungalow with two roof slopes? Easy to calculate, efficient to work on.
A detached house with:
- Main roof
- Dormer extension
- Flat roof section over the kitchen
- Porch canopy
- Conservatory connection
That’s five different roof areas requiring different approaches, different materials, and different expertise.
Typical prices per m² (2026, including labour):
- Concrete tiles: £45-70/m²
- Natural slate: £90-150/m²
- Clay tiles: £70-110/m²
- Flat roof (EPDM): £80-120/m²
A 100m² roof in concrete tiles: £5,000-7,000 for materials and installation. Same roof in natural slate: £9,000-15,000.
Factor #2: What’s Under the Tiles
Here’s where quotes diverge dramatically.
Your roof isn’t just tiles on top. It’s:
- Tiles (the visible layer)
- Battens (wooden strips the tiles hook onto)
- Underlay/felt (waterproof membrane under the battens)
- Rafters (the structural timbers)
- Insulation (increasingly required by building regs)
When we strip your old tiles, we find out what condition everything underneath is in.
Best case: Battens and felt need replacing (standard), rafters are perfect.
Worst case: Rafters have wet rot. Insulation is waterlogged. Wall plates are compromised. The structural timber quote just doubled your total.
A good roofer will caveat the quote: “Based on visual inspection—if we find timber issues once stripped, additional costs apply.”
A bad roofer will either lowball knowing they’ll hit you with extras, or price high assuming the worst without actually checking.
Factor #3: Access
That £23,000 quote I mentioned? About £4,500 of it was access.
The house was:
- Three storeys plus attic conversion
- On a busy main road requiring traffic management
- With a narrow side passage (no rear access)
- Adjacent to a commercial premises requiring coordination
Scaffolding alone was £3,200. Traffic management license and barriers: £450. Coordination delays: factored into labour.
The £14,500 quote was for a bungalow with a driveway and garden access on all sides. Scaffold: £800. Done.
Access factors that add cost:
- Building height (scaffold gets exponentially more expensive above 2 floors)
- Rear access or lack thereof
- Traffic management on busy roads
- Pedestrian protection on footpaths
- Conservation area restrictions
- Listed building requirements
- Nearby trees requiring protection
- Overhead cables needing temporary relocation
I’ve quoted jobs where scaffold and access was more than the roofing work itself.
Factor #4: Material Quality
Not all tiles are equal. Not all underlay is equal. Not all lead is equal.
Tiles:
- Budget concrete interlocking: £8-15/tile, 25-30 year lifespan
- Premium concrete: £15-25/tile, 40-50 year lifespan
- Natural slate: £3-15/slate (depending on source), 80-150 year lifespan
The difference between a budget tile job and premium materials can be £3,000-8,000 on an average house. The budget job will need replacing again in your lifetime. The premium job won’t.
Underlay:
- Basic felt: £15-25/roll, 15-20 year lifespan
- Modern breathable membrane: £40-80/roll, 30-50 year lifespan
Modern breathable membrane costs twice as much but reduces condensation problems, extends tile lifespan, and won’t need replacing as soon.
Fixings:
- Galvanised steel nails: Fine for 30-40 years in sheltered locations
- Stainless steel or copper: Lifetime durability, essential in coastal areas
The premium fixings add maybe £200-400 to a job. Cheap fixings in the wrong environment mean nail sickness in 25 years and a complete re-fix.
Factor #5: Stripping vs. Overlay
When your existing tiles are failing, you have two choices:
Strip and replace (recommended):
- Remove all existing tiles
- Remove old battens and felt
- Inspect timber structure
- Install new felt/membrane
- Install new battens
- Install new tiles
This is the proper job. It’s also the expensive job.
Overlay (sometimes possible):
- Leave existing tiles in place
- Install new battens over the top
- Install new tiles on the new battens
This is cheaper (no strip labour, no disposal) but problematic:
- Adds significant weight to roof structure
- Doesn’t address underlying issues
- Can void insurance (undeclared material change)
- Looks bulkier, sits higher than original
- Many roofers won’t warranty it
Some quotes come in cheap because they’re proposing overlay. Make sure you know which approach you’re getting.
Factor #6: Insulation Requirements
Building regulations have changed. If you’re doing a full roof replacement, you may be required to bring insulation up to current standards.
This isn’t optional if you’re going through Building Control.
What that can add:
- 150mm rigid insulation board: £2,000-4,000
- Ventilation modifications: £500-1,500
- Building control submission: £500-800
Some quotes exclude this. Some include it. Make sure you’re comparing like with like.
Factor #7: Warranty and Insurance
What happens if something goes wrong?
A cheap quote often comes with:
- No written warranty
- “We’ll come back and sort it” verbal promises
- Roofer not insured or underinsured
A proper quote includes:
- Written warranty (minimum 10 years workmanship, ideally 20)
- Manufacturer’s warranty on materials (20-50 years depending on product)
- Full public liability insurance
- Professional indemnity where applicable
These protections cost money. The roofer with the proper setup has higher overheads. Those overheads are in your quote—but they’re also your protection.
Factor #8: Who’s Actually Doing the Work
When you get a quote from “ABC Roofing,” who turns up to do the job?
Scenario A: ABC Roofing’s own trained employees. The company is responsible. Standards are controlled. If something goes wrong, you deal with ABC.
Scenario B: ABC Roofing subcontracts to whoever’s available. Maybe skilled tradesman, maybe not. If it goes wrong, ABC blames the sub, the sub is gone.
Scenario C: “ABC Roofing” is one bloke with a van. He hires labourers as needed, day by day. Different crew every day. No continuity, no accountability.
Higher-quality companies with employed tradesmen charge more. There’s a reason.
Factor #9: Time of Year
Roofing is weather-dependent and demand-fluctuates.
Peak season (spring and summer): Higher demand, fuller diaries, prices at normal or premium rates.
Autumn: Storm season approaching. Rush of “I should get this done before winter” jobs. Prices firm.
Winter: Weather disrupts work. Jobs take longer. Some roofers reduce prices to keep crews busy; others raise them to cover weather delays.
January-February: Often the quietest time. Some roofers offer modest discounts to fill the diary.
If your roof can wait, January bookings sometimes save 5-10%. But if you’re leaking, you’re paying whatever the market demands.
Factor #10: The Company’s Workload
A roofer who’s booked solid for six months can afford to be selective. They’ll quote higher because:
- They don’t need the work urgently
- If you say yes, great; if not, they’ve got plenty of jobs
- Higher prices mean fewer jobs to manage, same revenue, less stress
A roofer who’s desperate for work will quote low to win the job. You might think that’s good for you, but ask yourself: why are they desperate? Where did their other customers go?
The best roofers tend to be busy. Expect their prices to reflect that.
Why the “Cheapest Quote” Is Risky
I’m not telling you to always pay the highest price. But I am telling you this:
If you get three quotes—£12,000, £18,000, and £19,000—the £12,000 one needs scrutiny.
Why is it 30% cheaper?
- Lower quality materials?
- No proper scaffolding?
- Cash job with no warranty?
- No insurance?
- They haven’t spotted something the others have?
- They’re desperate and cutting corners to win work?
Sometimes the cheap quote is legitimate. Maybe they’ve got lower overheads, fewer employees, a genuine efficiency advantage.
But often, cheap quotes become expensive problems. Paid twice—once for the bodge, once to fix it.
How to Compare Quotes Properly
When you have three quotes in hand:
Check the scope is identical:
- Same materials specified?
- Same approach (strip vs overlay)?
- Same access arrangement?
- Same waste disposal included?
- Same warranty terms?
Check the detail:
- Is it itemised?
- Can you see what you’re paying for?
- Are there caveats about hidden issues?
Check the company:
- Reviews online?
- How long established?
- Insurance verified?
- Warranty in writing?
The quote that’s £2,000 cheaper but comes from an uninsured bloke with no Google presence isn’t actually cheaper—it’s a gamble.
What a Good Quote Looks Like
Here’s what I provide on every roof replacement quote:
- Site survey report: What I found, what condition it’s in
- Scope of work: Exactly what’s included
- Materials specified: Brands, types, quantities
- Access arrangements: Scaffold spec, permit requirements
- Timeline: How long the job takes
- Price breakdown: Materials, labour, access, waste, VAT
- Payment terms: Deposit amount, stage payments, completion payment
- Warranty: Workmanship and materials, in writing
- Insurance confirmation: Available on request
- Caveats: What happens if we find hidden issues
If your quote doesn’t have most of this information, ask for it. If they can’t provide it, find someone who can.
Final Thought
A roof replacement is one of the biggest spends you’ll make on your home. It should last 30-100 years depending on materials.
Don’t choose based on the bottom line alone. Understand what that number includes. Know what you’re getting—and what you’re not.
The right roofer at a fair price, with proper materials and full warranty, is worth more than the cheapest quote from someone you’ll never see again.
Want a quote you can actually understand?
We provide fully itemised, transparent pricing with everything explained.
Or call: +44 89 981 9675
Seamus O’Brien has been quoting roofs for 20 years. He’s never once regretted charging a fair price for proper work.
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