Introduction

If you work in occupied homes, damp and mould is back on the front burner. Why? New expectations, tighter response times, and clients (landlords, agents, lenders) who want evidence, not opinions. This guide lays out what's changing in 2025, how it hits your day-to-day, and what to do about it. No fluff—just practical moves, real specs, and examples you can use this week.

Table of Contents

• Key Takeaways
• Why Damp And Mould Are Back In The Spotlight
• Trend 1: Response Times Are Becoming Regulated
• Trend 2: Diagnostics Are Moving From Guesswork To Data
• Trend 3: Ventilation Upgrades Are Standard, Not Optional
• Trend 4: Materials And Methods Shift To Root-Cause Fixes
• Trend 5: Documentation Is Now A Deliverable
• Impact On Small Contractors: Pipeline, Pricing, Risk
• Action Checklist For 2025 Readiness
• Frequently Asked Questions
• Conclusion

Key Takeaways

• Damp and mould jobs now expect evidence: common benchmarks include 40–60% indoor RH targets and timber under 16–20% WME before close-up.
• Government proposals commonly reference timeframes like investigating complaints within 14 days and starting repairs within 7—be ready to show dates and proof.
• Ventilation specs are clearer: commonly used UK rates under Approved Document F include 15 l/s in bathrooms and 30 l/s in kitchens, plus 15–30 minute run‑on.
• Mould can colonise within 24–48 hours on persistently wet surfaces—rapid response and drying matters.
• Clear, signable scopes reduce callbacks; many contractors find e‑signatures and fast, photo‑backed proposals can cut back‑and‑forth by half.

Why Damp And Mould Are Back In The Spotlight

The Problem

Complaints are rising, and tolerance is falling. Landlords, agents and lenders now push for faster action, documented diagnostics, and durable fixes—not just a quick wash-down and paint.

The Solution

Treat damp and mould like a compliance job. That means triage timelines, consistent measurements, and clear acceptance criteria in your scope. Keep it simple, repeatable, and defensible.

Real‑World Example

A small maintenance contractor in Manchester switched from “visual only” to a 20‑minute survey routine: ambient RH/temperature, surface temp check, spot moisture meter, and vent extraction test. With simple evidence in each proposal, disputes dropped, and approvals sped up because agents could forward a professional, photo‑backed narrative.

Trend 1: Response Times Are Becoming Regulated

The Problem

Slow or vague responses create risk. Social housing is driving clearer timelines and private rentals follow their lead.

The Solution

Adopt service levels that mirror emerging expectations. Government proposals commonly set investigation within 14 days and repairs starting within 7. Build these dates into your workflow, and show them on the proposal and the job confirmation.

Practical Details

• First contact and risk triage: within 48 hours.
• Site inspection booked: within 7–10 days where possible.
• Works start: aim inside the 7–14 day window for urgent cases.
• Record dates for complaint, inspection, and start/finish in your job file.

Example

Add a small table in your proposal:

Trend 2: Diagnostics Are Moving From Guesswork To Data

The Problem

“Looks like condensation” doesn’t cut it anymore. Clients want to see readings, not just opinions.

The Solution

Standardise a light, defensible diagnostic kit and routine.

Technical Details

• Relative Humidity: aim for 40–60% indoors for healthy conditions.
• Mould growth window: commonly 24–48 hours on surfaces that remain wet or at dew-point.
• Wood Moisture Equivalent (WME): keep structural/joinery timber under 16–20% before sealing or boxing-in.
• Surface temperature: check against dew‑point; cold bridges are common on solid walls and window reveals.
• Ventilation: note fan type and extraction performance; poor flow is a frequent root cause.

Example

On a 1930s semi, bathroom shows 72% RH after showers and a cold external corner at 12°C with room at 20°C. Proposal includes: upgrade to a 15 l/s continuous fan with humidistat and 20‑minute run‑on, insulate cold corner with 10–12 mm insulated lining, and set post‑works RH target under 60% during normal use.

Trend 3: Ventilation Upgrades Are Standard, Not Optional

The Problem

Painting over mould without airflow fixes is a fast track to callbacks.

The Solution

Specify ventilation as part of the fix, not a nice‑to‑have.

Technical Details (Common UK Practice Under Approved Document F)

• Intermittent bathroom extract: typically 15 litres per second with 15–30 minute run‑on.
• Kitchen extract: commonly 30 l/s adjacent to hob (60 l/s if hood is the only extract during cooking).
• Continuous MEV or dMEV: increasingly used in retrofits to stabilise whole‑house moisture.
• Trickle vents and background ventilation: keep rooms supplied so extract can actually work.

Example

Small flat with recurring bedroom mould. Scope: dMEV in bathroom, new cooker hood ducted outside, ensure openable trickle vents in bedrooms/living, and a simple user brief. Post‑works, RH settles near 50–55% in normal occupancy.

Trend 4: Materials And Methods Shift To Root-Cause Fixes

The Problem

“Bleach and brilliant white” lasts a season, then the phone rings.

The Solution

Combine cleaning, blocking, thermal correction where needed, and a vapour‑open finish.

Practical Specification Moves

• Clean: biocidal wash rated for mould; allow dwell time and thorough dry.
• Block: stain‑blocking primer where needed to mask residual shadowing.
• Thermal bridge: 6–12 mm insulated lining on cold spots (reveals, external corners) can lift surface temperature by several degrees Celsius.
• Finish: vapour‑open paints that tolerate occasional high RH.

Example

North‑facing solid wall room: recurring mould behind a wardrobe. Scope includes 10 mm insulated lining on the flank wall, 25 mm stand‑off from furniture, vapour‑open finish, and a user note. Callback risk drops because the surface no longer sits at or near dew‑point.

Trend 5: Documentation Is Now A Deliverable

The Problem

Agents and insurers increasingly want proof: before/after photos, specs, and acceptance of the maintenance notes.

The Solution

Turn your proposal into a concise report that clients can forward without edits. Include a narrative, readings, product choices, and acceptance criteria.

What To Include

• Summary of findings with 3–5 photos.
• Key readings: RH/temp, spot WME, fan performance notes.
• Works scope with products and ventilation spec (e.g., 15 l/s, 20‑minute run‑on).
• Acceptance criteria: “Post‑works RH under 60% in normal use; timber under 16–20% WME before close‑up.”
• Simple user guidance: door left ajar after showers, trims of furniture from cold walls, vent use.

Fast Admin Win

Capture your site notes by voice and photos, then generate a clean, signable PDF the same day. With Donizo, you can speak your findings on site, attach photos, and produce a professional proposal fast. Clients sign with e‑signature, and when they accept you convert it to an invoice in one click. Many contractors find this cuts 1–2 hours of admin per job and reduces back‑and‑forth because the scope is clear.

Impact On Small Contractors: Pipeline, Pricing, Risk

The Problem

More requests, higher expectations, and tighter timelines add pressure on small teams.

The Solution

Systemise the small stuff. Standard surveys, standard scopes, and rapid, signable proposals minimise risk and win work faster.

Practical Impacts

• Demand: damp/mould calls often spike in colder months and in poorly ventilated stock.
• Pricing: build diagnostics time and ventilation works into quotes; avoid “paint only” unless it’s explicitly surface mould with stable RH.
• Risk: define exclusions (structural damp, roof leaks, underground water ingress) and refer when readings suggest other causes.

Quick Comparison

Action Checklist For 2025 Readiness

1. Standardise A 20‑Minute Survey

• RH and temperature (room)
• Surface temp at cold spots
• Spot WME on timber or plaster
• Fan spec and performance notes
• 3–5 photos of key areas

2. Pre‑Build Three Scope Templates

• Condensation‑led mould, no building defects
• Condensation plus cold bridge (add insulated lining)
• Condensation plus inadequate ventilation (fan and background air)

3. Put Targets In Writing

• Indoor RH 40–60% in normal use
• Timber under 16–20% WME before close‑up
• Bathroom extract 15 l/s with 15–30 min run‑on; kitchen 30 l/s at hob

4. Define Exclusions And Escalations

• Rising damp, roof leaks, plumbing leaks—investigate or refer.
• If WME stays high despite drying, pause works and advise investigation.

5. Document Timelines

• Log complaint date, inspection date, start date.
• Mirror the commonly referenced 14‑day investigation and 7‑day repair start windows where possible.

6. Use Same‑Day Proposals

• Capture findings by voice and photos on site.
• Generate a signable proposal with Donizo, send it, and let clients e‑sign.
• Convert to invoice on acceptance—no retyping.

7. Hand Over A Simple User Brief

• Door ajar post‑shower; vent on boost; furniture off cold walls.
• State that failure to follow guidance can reintroduce mould despite works.

Frequently Asked Questions

Do I Need Air Or Swab Testing For Every Job?

Generally, no. Most residential damp and mould issues can be scoped from RH/temperature, surface temperature, WME readings, and visible patterns. Reserve lab tests for disputed cases or when health professionals request them.

What Ventilation Spec Should I Use As Default?

Common UK practice under Approved Document F is 15 l/s in bathrooms (with 15–30 minute run‑on) and around 30 l/s at the kitchen hob. In small flats with persistent moisture, consider continuous dMEV or MEV to stabilise whole‑house moisture levels.

Can I Guarantee The Mould Won’t Come Back?

Guarantee workmanship and materials, but set realistic limits. Make clear that maintaining 40–60% RH, using extract fans, and avoiding blocking vents are client responsibilities. If those aren’t followed, recurrence risk rises.

How Should I Price A Damp And Mould Job?

Price the diagnostic survey time, then build scope items: cleaning, stain‑block, thermal lining if needed, and ventilation works. Include making‑good and a short user handover. Make exclusions explicit for defects like leaks or rising damp.

How Fast Can I Close These Jobs Without Cutting Corners?

Mould can colonise in 24–48 hours on wet surfaces, so speed matters—but evidence first. Many contractors aim for inspection inside 7–10 days, then start within the next week where urgent. Using same‑day, signable proposals with photo evidence helps approvals land faster.

Conclusion

Damp and mould work in 2025 is about proof, not guesswork. Build a light diagnostic routine, specify ventilation properly, fix cold bridges where they matter, and hand over a clear user brief. The admin can be just as tight: talk through your findings on site, attach photos, and send a professional, e‑signable proposal the same day. Donizo makes that easy with voice‑to‑proposal, e‑signature, and one‑click invoice conversion so you spend less time typing and more time delivering fixes that last.