FAQs
Questions about mould surveys, fogging and window film surveys
Straight answers before you book: what a survey finds, what it costs, and when you need someone else.
Can't see your question? Send it with the enquiry form or on WhatsApp, and you'll get a straight answer.
In short
Simply Filtered answers common questions about mould surveys, antimicrobial fogging, window film surveys, ventilation and water damage assessments in London. Every visit is carried out by its founder, Duncan Ridley. Simply Filtered doesn't find leaks, diagnose rising damp or carry out building or ventilation work, and says so when a different specialist is needed.
Mould surveys
How much does a mould survey cost?
A mould survey includes the visit and your written report. The price depends on your home. Send the form for a free quote, with the exact price and what's included, before anything is booked.
What does a mould survey involve?
A visit to your home, with readings in each room you're worried about: humidity, dew point and surface temperatures, plus thermal imaging and airflow checks where they help. Nothing is drilled or lifted.
You then get a written report on what's causing the mould and what it will take to deal with it.
Is a mould survey the same as a damp survey?
Not quite. A mould survey finds out why mould is growing, which in most homes means condensation, and what it will take to deal with it. A damp survey usually looks at the building itself for rising or penetrating damp.
Why does mould keep coming back after I clean it?
Because cleaning removes the mould but not the moisture feeding it. Until you know why condensation forms in that spot, it comes back. Why mould keeps coming back explains more.
Does a mould survey include getting rid of the mould?
No. The survey finds the cause and sets out the plan. If the plan needs ventilation or building work, a trusted third party can do it, or you can use your own contractor.
How we work
Will you try to sell me work?
No. Building, repair and ventilation work aren't part of the service, so there's nothing to sell you beyond the survey.
If your plan does need work, you're free to use anyone you like, with no obligation to use anyone we recommend.
Do I have to use the contractors you recommend?
No. Your report is yours to use with any contractor you choose. If you'd like an introduction to a trusted third party, ask, and there's no obligation either way.
Who will visit my home?
Duncan Ridley, the founder of Simply Filtered. He carries out every survey and fogging visit and writes every report himself, so the person you speak to is the person who comes.
Do you find leaks or diagnose rising damp?
No. If your readings point to a leak or rising damp, your report says so and tells you which specialist to call, with the evidence to hand them.
Renting, letting and buying
Is a mould survey worth it for a landlord?
If your tenant has reported mould and you're not sure what's causing it, yes. You get an independent record of what was measured and what's proportionate to do, which you can keep on file and share with your tenant.
Who pays for a mould survey?
Whoever books it. That's usually the homeowner, or the landlord or letting agent when a tenant reports mould. Tenants can also book one themselves. See mould surveys for landlords or independent reports for tenants.
Will my landlord have to accept the report?
We can't promise that. The report is independent and based on measurements, which is what makes it worth sharing.
Does Awaab's Law apply to my rented home?
If you rent from a council or housing association in England, yes: it has applied to damp and mould since 27 October 2025. See GOV.UK: Awaab's Law in the social rented sector.
It doesn't apply to private rentals yet. Private landlords already have legal duties around damp and mould, and Awaab's Law is expected to be extended to private rentals. See the GOV.UK guide to the Renters' Rights Act.
Is a mould survey a replacement for a RICS survey?
No. A building survey covers the whole property. A mould survey is a focused investigation into the mould, with measurements, and you can have both.
Antimicrobial fogging
Does antimicrobial fogging get rid of mould?
Not on its own. Fogging reduces mould spores in the air and on surfaces, which makes it a useful hygiene step after mould, a leak or a clean-up. It doesn't fix what's causing the mould, and it isn't guaranteed to stop mould coming back.
If you don't know the cause yet, start with a mould survey.
How long do I need to stay out of the house?
3 to 4 hours. Your home needs to be empty of people and pets for that time, so most people plan a morning or an afternoon out.
How much does antimicrobial fogging cost?
Fogging starts from £380. The price depends on the size of your home and how many areas need treating, and your free quote gives you the exact figure.
Is fogging covered by home insurance?
Fogging is often covered as part of a home insurance claim. Check with your insurer.
Will my home smell afterwards?
That's your choice. Pine Fresh leaves a clean, light fragrance. Odourless adds no scent at all.
Window film surveys
Does the window film survey include the film?
No. The survey is a diagnostic assessment and does not include installation or film supply. Toughened glass is reported as "toughened" or "not toughened". The survey does not certify glass as safety glass or as meeting any British Standard.
You can take your report to your own film supplier or installer, or ask us to pass it to local suppliers who can advise and quote.
How do I know if my glass is toughened?
Toughened glass often has a small etched mark in one corner, but not always, and laminated glass and Low-E coatings usually can't be spotted by eye. On a survey, each of your panes is tested with a Merlin Lazer toughened glass indicator and recorded as toughened or not toughened.
Can window film crack double glazing?
It can when the film doesn't suit the glass. Fitting the wrong film to the wrong glass can cause cracking, failed double-glazing seals and voided warranties. Measuring the glass first lets your supplier choose a film that suits it.
How much does a window film survey cost?
Prices start from £150 for a small flat, and depend on how many windows you want measured. A base fee of around £100 covers travel, setup and your written report, plus roughly £12 to £15 per window, or per sealed unit where a window has several panes. Say roughly how many windows you want measured and you get an exact price.
Does the survey certify my glass as safety glass?
No. Toughened glass is reported as toughened or not toughened. The survey does not certify glass as safety glass or as meeting any British Standard.
Ventilation
Can better ventilation stop condensation and mould?
It often makes the biggest difference, because it moves moist air out before it settles on cold surfaces. It can't fix a leak or a very cold wall on its own, which is why the survey looks at the whole picture first.
How do I know if my extractor fan is working?
Signs it isn't: steam lingers after a shower, the mirror stays misted, or the fan is noisy but weak. On a survey, an anemometer measures whether your fan is actually moving air.
Do you install ventilation?
No. Installation is carried out by trusted third parties or your own contractor. You can opt in to have quotes arranged when you enquire, and there's no obligation to use anyone we recommend.
After a leak or flood
When should I get a water damage assessment?
Once the source of the water has been stopped or fixed. The sooner your home is assessed after that, the sooner you know what needs drying and what has to come out.
Can you find the leak?
No. We don't do leak detection. If water is still getting in, a leak detection company or a plumber is the right first call, and the assessment comes once the leak is fixed.
Is the report the same as a quote for the repair work?
No. The report is an assessment of what your home needs. It isn't a quote for the work, and you're free to get the work quoted and done by anyone you choose.
Where we work
Do you cover my area?
If you're in London inside the M25, yes, wherever you are in the city.
If you're just outside the M25, get in touch and you'll get an honest answer on whether a visit is possible.
Next step
Still have a question?
Ask it with the enquiry form or on WhatsApp, and you'll get a straight answer and a free quote. There's no obligation to go ahead.
WhatsApp usOr call 07366 199261