Prices
What it costs
Most firms in this trade will not put a number on a website. We will, for everything we can be straight about — and for the work where the price genuinely depends on your house, we have written down what moves it, so you can see the shape of it before you ring anyone. Every price on this page includes VAT.
Because the most common reason somebody does not ring is that they have no idea whether this is a two hundred pound problem or a six thousand pound one, and nobody in this trade will tell them. That is not a good enough reason to leave a house damp.
So the survey is a fixed price and it is at the top of this page. Servicing is fixed by the size of the unit. Installation is a range, because a fan on an outside wall and a fan in the middle of a flat are genuinely different jobs — and we would rather show you the range and tell you what moves it than quote a number we have to take back.
Start here — the survey
The only thing you need to buy before anyone can tell you what is actually wrong.
Damp & mould survey
£390
including VAT · about two hours on site£540 for a larger or more complicated property — four bedrooms and up, or somewhere that has already had remedial work that did not hold. We tell you which applies when you describe it, not when we arrive.
What you get for it
Readings taken rather than guessed: surface temperatures, humidity, and the actual airflow from every fan you already have, measured at the grille. We find where the moisture is being made and which cold surfaces it is landing on — including the ones behind furniture you cannot see yet. Then we tell you which of the three damps it is: condensation, something coming in from outside, or rising damp. All of it in writing afterwards, with the readings and dated photographs.
Why it is not free
Most damp companies survey for nothing, and there is a reason: the survey is how they sell you the remediation, so the answer is largely decided before they knock. We charge because the answer is the product — something you can put in front of a tenant, a council or an insurer. If it turns out not to be a ventilation problem, we say so and tell you which trade you actually need. You would not get that from a survey somebody was giving away.
Fixing it
A range on each, honestly, with what decides where you land written underneath. Every figure includes VAT and the parts. Where a job has a unit in it, the figure depends on the unit chosen — and we tell you which one, and what it costs, before you commit to anything.
£239 – £395
Depending on the unit chosen
Extract fan replaced, like for like
New fan, new grille, and an airflow test at the end so you know it moves what it should.
What moves it: whether the existing duct is sound. If it is not, it is the next card.
£450 – £1,100
Depending on the unit chosen
Extract fan with a new duct run
A different job, and the one people are not warned about. Needed when the duct is crushed, far too long, or discharging into your loft — which we find a lot.
What moves it: loft or external wall, the run length, and making good afterwards.
£340 – £450
Depending on the unit chosen
Continuous (dMEV) fan replaced
A fan designed to run quietly all the time on trickle rather than in bursts, which is what actually keeps a wet room dry.
What moves it: whether the existing wiring suits a fan that runs all the time.
£450 – £950
Extract duct re-routed or upgraded
Replacing sagging flexible duct with rigid, shortening the run, or taking it out to a proper terminal.
What moves it: how far it has to go, how much ceiling has to come down, and access.
£450 – £750
Depending on the hood chosen
Cooker hood ducted to outside
A recirculating hood filters the grease and puts every bit of the steam back in the room. This is the job that stops that.
The figure is the ducting — the run to outside, the terminal and making good — with the hood you already have reconnected to it. If yours only recirculates and cannot be converted, or you would like a new one, the hood is added on top, and what that costs depends on the one you choose.
What moves it: the route to the nearest outside face, and whether units have to come out to reach it.
£900 – £1,350
Depending on the unit chosen
Positive input ventilation (PIV)
One unit in the loft gently pressurising the house, which pushes the damp air out through the background ventilators. A standard loft unit sits at the lower end; a heated one, which tempers the air on a cold day, at the top.
What moves it: loft access, and whether it can draw from the loft at all. A flat, or a loft you would not want to breathe from, needs a ducted intake to outside instead — that is quoted, because it depends on the route.
£1,900 – £3,800
Depending on the unit chosen
Heat recovery unit replaced
Swapping an existing unit that has failed or is long past its filters, reusing the ductwork that is already there.
Most of the spread is the unit itself: which one a house needs depends on how many wet rooms it has to serve and what will physically fit the ductwork already in the ceiling. Every one is recommissioned to its design rates and you get the readings in writing. We tell you which unit, and the whole price, before you commit to anything.
What moves it: beyond the unit, whether the existing spigots line up. They almost never do, and the adaptors are the difference between a day and a day and a half.
The one that catches people out. If the wet room has no outside wall behind it — common in conversion flats, and in bathrooms added off a landing — a wall fan is not an option at all. It needs an inline fan in the ceiling void and a duct run out to the nearest external face: most of a day with a ceiling open rather than a couple of hours. It is the biggest single price difference in this work and almost nobody is told before the quote arrives. We tell you on the phone.
A full heat recovery system: what to budget
Budget figures, not quotes. The size of the house puts you in a band, and the unit chosen does most of the work of deciding where in it you land. Supplied, installed, commissioned and measured, with the figures for every terminal in writing. Retrofit into an existing house unless stated.
£5,000 – £6,500
Budget · depending on the unit chosen
Flat, or a small one to two bedroom house
£6,000 – £8,500
Budget · depending on the unit chosen
Two to three bedroom house
£9,000 – £13,000
Budget · depending on the unit chosen
Four bedrooms
£13,000 – £18,000
Budget · depending on the unit chosen
Five bedrooms, or a complicated retrofit
New build or first fix, before the boards go on, is roughly 25–30% less — and that gap is the single best argument for talking to us early. Four things decide where a house lands in its band: how the ducts can be routed (open joists are a different job from a finished house), where the unit can go and how far it is from the outside, which unit — there is a real spread in efficiency, noise and filter cost — and how much making good is needed once it is in.
Keeping it working
A heat recovery unit needs filters and a clean once a year. Miss it and the airflow drops away quietly — nothing on the wall tells you, and the first sign is usually condensation coming back.
£199 a year, flat
£265 house · £325 large
Or £18 – £28 a month. Filters included, full clean, and every valve measured with the figure written down next to last year’s — which is the part nobody else does. One reading tells you it works today; a reading every year tells you whether it is drifting, and why.
We pick the month, you get the lower price. That is the whole deal — it lets us do several in one area on the same day, and we pass it back.
£225 – £365
One-off service, without a plan
£225 for a flat up to six valves, £299 for a house with seven to ten, £365 for eleven and up. Each additional unit at the same address is £95.
Same work either way — you just choose the date, and there is no reminder when it falls due next year.
£264
Heat recovery fault visit
Diagnosis, a full airflow test, and the repair itself if we can finish it on the day with what is on the van — which covers most of them: a blocked condensate trap, choked filters, a stuck summer bypass, a dirty impeller.
One fee, not two. If a part has to be ordered we quote it, and you do not pay a second call-out when we come back.
£350 – £450
Rebalance and airflow test
Every valve set to the design rate and the readings recorded. £350 up to six valves, £450 for seven to twelve.
Worth having if rooms feel uneven, if it has never been commissioned, or if you have just bought the house.
Landlords, letting agents and managing agents. Portfolio work is quoted rather than priced from a table, because how many properties there are, how far apart they sit and how much of the paperwork you need change it far too much for any published figure to be honest. Rates for you are quoted excluding VAT, which you reclaim. There is more on what moves the price, and what to send us for a quick quote.
Why we are not the cheapest
An electrician can fit an extract fan, and most of them do it properly. We are not going to pretend otherwise. The difference is what happens once it is on the wall.
We measure it. Every fan we fit gets an airflow reading taken at the grille with a calibrated meter, and you get the number in writing. A fan that says 15 l/s on the box can be moving seven through four metres of flexible duct with a bend in it — and it sounds exactly the same while it does it. Noise is not airflow. Without a meter nobody knows: not you, and not whoever fitted it. You find out the following winter, when the mould comes back and the fan gets blamed for something the duct was doing.
That reading is also the document a building control officer, an insurer, a council environmental health officer or a tenant’s solicitor will ask for, and we can produce it. So can the QR label on the unit, for as long as it is on the wall.
The rest is unglamorous and it is where the money goes: we diagnose before we fit, because a crushed or blocked duct is the usual cause and a new fan on a bad duct is a callback with our name on it. We use rigid or semi-rigid duct on the shortest route the building allows, fixed so it cannot sag. We fit the backdraught shutter. We check it terminates outside, which a surprising number do not. And we are a limited company, VAT registered and insured, with a twelve month guarantee on our workmanship in writing.
And if all you need is a like-for-like swap on a duct that is already sound, a good local electrician is the right answer and we will tell you so on the phone. We would rather do that than take the job and have you feel it was not worth it.
Questions about price
Yes. Every figure on this page is what you pay, with VAT included and materials included unless a range says otherwise. We are a VAT registered limited company, so the VAT is genuinely due and it is shown rather than added at the end — a quote that turns out to be twenty per cent more than the website said is not a good start. Landlords, letting agents and managing agents are quoted excluding VAT instead, because you reclaim it and comparing ex-VAT figures is the only way you can compare us against anyone else properly.
Because a free survey is a sales visit, and the answer it produces tends to be the one that sells the most work. Damp-proofing firms in particular give the survey away and then recommend an injected damp course, which is the remedy they sell — on a problem that is very often condensation happening a metre above where they have just drilled. We charge for ours because the answer is the thing you are buying: a dated, written assessment with the readings in it, that you can show a tenant, a council or an insurer. The clearest sign it is worth having is that we will tell you when the answer is not ventilation and not us, which is not a sentence anyone doing a free survey has much reason to say.
Because they are not quite the same job, and it is worth being honest about the difference rather than just claiming to be better. A good local electrician fitting a decent fan onto sound ductwork is a real option and sometimes the right one — we will say so if that is your situation. What the extra buys is the part nobody can see: we check the duct before we fit anything, because a crushed, sagging or blocked duct is the usual cause and a new fan on a bad duct is a callback; we use rigid or semi-rigid duct on the shortest route, fixed so it cannot sag; we fit the backdraught shutter; we confirm it actually terminates outside rather than in your loft, which a surprising number do not. Then we measure the airflow at the grille and give you the figure in writing. A fan rated 15 l/s can deliver seven, and it sounds identical while doing it.
No to both. Coming out to look at a job and price it is free, and there is no call-out fee added to any price on this page. The survey is different and it is not a call-out charge — it is two hours of measurement and a written report, and it is a product in its own right rather than the cost of getting us through the door. If what you want is a quote for a specific piece of work you have already decided on, that costs nothing.
Four things, roughly in order of how much they matter. How the ducts can be routed — a house with open joists before plastering is a completely different job from a finished house where ceilings have to come down and go back up. Where the unit can go and how far it is from the outside walls, because every metre of duct is time and material. Which unit, as there is a real spread in efficiency, running noise and what the filters cost to replace each year. And how much making good is needed afterwards. The size of the house decides which band you are in; within the band, the unit chosen and how much of the building has to be opened up decide where you land. That is why every system figure on this page is a budget rather than a quote — the quote comes once the unit is picked and the duct routes have been walked.
Yes, and we will fit it properly. Two things to know before you do. Our twelve month guarantee covers our workmanship either way, but it cannot cover a unit we did not supply — if that unit fails you are dealing with the manufacturer or the retailer directly, rather than with us. And it is worth a conversation first, because the commonest problem with a customer-supplied fan is that it is the wrong type for the duct run: a standard axial fan is designed to go straight out through a wall, and asking it to push air along several metres with bends in it will not work whatever the box claims. We would rather tell you that before you have bought it.
Not at all. If you already know what you want — a fan replaced, a duct re-run, a unit serviced — we will quote it for nothing and get on with it. The survey is for the situation where there is damp or mould and nobody yet knows why, which is the case where guessing is expensive: fitting ventilation to a leak fixes nothing, and so does injecting a damp course into a condensation problem. If you are unsure which of those you are in, describe it to us on WhatsApp and we will tell you honestly whether a survey is worth your money.
For small work, in full on completion once you have seen it working and have the airflow figures. Where a job carries a significant material cost — a heat recovery system, or anything where units and ductwork are ordered specifically for you — we ask for a deposit before ordering, with the balance due on completion. On work running beyond about a fortnight we agree staged payments in advance so neither of us is carrying the whole job. All of it is set out in our terms and conditions, and it goes on the quote in writing before anybody starts.
Not sure where to start?
Send us a message with what you have noticed at home. We will tell you honestly whether you need a survey, a system, or neither.
Or see what it costs — unlike most in this trade, we publish our prices.
Trained on the systems we install
Certificated — and here they are
Most trade sites show you a row of logos. These are the actual certificates, held by this business. Tap either one to read it, or download the PDF.
- 12-month workmanship guarantee On top of the manufacturer’s warranty, which we register in your name. If anything we installed fails because of the way we installed it, we come back and put it right. What it covers.
- Company no. 12092552 Registered in England & Wales. Trading as Cavalli Ventilation since July 2019, and in ventilation since 2003.
- Airflow measured on every install A calibrated anemometer at the grille, recorded and handed over. The only figure that counts is the one measured in your room.