COST GUIDES
Durgo valve cost (air admittance valve)
Updated 07/26
Fast Facts
Typical supply and fit cost: £100–£200
Average installation cost: £150
Biggest cost drivers: Installation complexity and pipework alterations
If you're experiencing gurgling drains or unpleasant smells, a Durgo valve (also called an air admittance valve) can often improve drainage ventilation without extending a soil pipe through your roof.
This guide explains typical Durgo valve installation costs, what affects the price and when it's worth hiring a plumber.
How much does installing a Durgo valve cost?
Most homeowners pay between £100 and £200 to have a Durgo valve supplied and installed.
If you also need an existing roof soil pipe removed, this typically adds around £85 to the overall cost.
| Item | Range - Low | Range - High | Average cost |
|---|---|---|---|
| Durgo valve installation | £100 | £200 | £150 |
| Remove soil pipe from roof | – | – | £85 |
| Plumber hourly rate | £40 | £60 | £50 |
| Last updated: July 2026 Our costs are ballpark averages - get a local tradesperson to quote now | |||
The total cost depends on where the valve needs to be fitted, whether any pipework needs adjusting and your plumber's hourly rate.
Compare quotes from checked plumbers
The easiest way to understand what your installation is likely to cost is to compare quotes from a selection of checked plumbers working in your area.
When requesting quotes, explain where the valve will be installed, whether you need an existing roof vent removed and if any new pipework may be required. Photos of the existing pipework can also help plumbers provide a more accurate quote before visiting.
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What does a Durgo valve do?
A Durgo valve, also known as an air admittance valve, is a one-way mechanical valve fitted to a soil pipe.
As wastewater drains away, negative pressure can build up inside the drainage system
The valve automatically opens to let air into the pipe, equalising the pressure and preventing water from being pulled out of sink, basin and toilet traps
Without adequate ventilation, you may notice slow-draining appliances, gurgling noises or unpleasant sewer smells inside your home
Installing a Durgo valve can often solve these problems without needing to extend a vent pipe through the roof.
If you're fitting a Durgo valve as part of a new bathroom or toilet installation, our toilet installation cost guide explains what the wider project typically involves.
Factors affecting the air admittance valve cost
Several factors influence the overall cost of installing a Durgo valve.
Installation complexity: Replacing an existing valve is usually quicker and simpler than installing a new valve where there wasn't one before. If new pipework is needed or an existing roof soil pipe has to be removed, labour costs will increase
Pipework alterations: Some installations require additional fittings or changes to the existing pipework before the new valve can be fitted
Valve specification: Smaller air admittance valves are generally inexpensive, while larger 110mm valves designed for soil stacks cost more
Accessibility: Pipework in lofts or accessible cupboards is usually easier to work on than pipework hidden inside boxed-in areas or walls
Location: Labour rates are generally higher in London and the South East than elsewhere in the UK
On Checkatrade, you'll only find trades who meet our high standards and pass up to 12 checks.
Where should a Durgo valve be installed?
A Durgo valve must be installed at least 200mm above the highest connected water trap in the drainage system. In most homes, this means fitting it inside the loft, within boxed-in pipework or inside an accessible cupboard.
The valve needs access to fresh air, so it shouldn't be completely sealed inside an enclosure. If it's boxed in, the box must have an open vent with at least 16 square inches of free air area.
Durgo valves are intended for internal use. If the soil pipe terminates outside the building, you'll normally need a suitable external-grade air admittance valve instead.
If you're fitting a Durgo valve as part of a new downstairs bathroom, see our downstairs toilet installation cost guide for what the full project typically involves.
Estimate your Durgo valve installation cost
The calculator below provides a guide price based on previous Checkatrade jobs.
Job Estimate Calculator
This calculator provides a guide price only. For a more accurate cost, compare quotes from a selection of checked plumbers working in your area.
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Can you install a Durgo valve yourself?
Replacing an existing Durgo valve on a compatible fitting is a manageable DIY job if you're confident working with plumbing pipework.
However, installing a new valve where one doesn't already exist, particularly if it involves modifying the soil stack or removing a roof vent pipe, is usually best left to a qualified plumber.
Work on soil drainage systems must comply with building regulations (Part H), and incorrect installation could affect how your drainage system performs or allow unpleasant sewer gases to enter your home.
If you're unsure, ask a plumber to assess the work before you begin. For smaller jobs, some plumbers may charge a minimum fee rather than working to an hourly rate.
How to find a plumber for a Durgo valve
Choosing an experienced plumber helps ensure your Durgo valve is fitted correctly and complies with building regulations.
Before requesting quotes, have the following information ready:
Where the soil pipe currently terminates (loft, roof or external wall)
Whether an existing roof vent pipe needs removing
Whether the existing pipework is easily accessible
If known, the diameter of the pipework (typically 32mm, 40mm or 110mm)
Comparing quotes from a selection of checked plumbers is the best way to understand what's included and find the right tradesperson for the job.
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FAQs
Yes. The most common failure modes are: (a) the membrane gets stuck closed, blocking air intake (lubricating the valve or replacing it usually fixes this); (b) the valve was installed in the wrong position, too close to a water trap or with no free air around it; or (c) a blocked waste pipe is creating back-pressure that overwhelms the valve. If you smell sewer gases, check the valve and the waste pipes before assuming the valve itself is faulty.
Yes, provided the boxing has adequate ventilation. The inlet area must be at least 16 square inches of open vent so sufficient air can reach the valve. A completely sealed box will prevent the valve from working and can trap sewer gases.
A Durgo valve should be at least 200mm above the highest water entry point in the system, typically the highest sink or basin trap connected to that branch of pipework. Most air admittance valves are installed at the end of a soil pipe in the loft for this reason.
Match the valve to your pipe size. The most common sizes are 32mm and 40mm for basin and sink branches, and 110mm for soil pipes (toilets and main stacks). Check the pipe diameter before buying: a 32mm valve will not fit a 110mm soil pipe.
A good-quality air admittance valve should last 20–30 years in normal use. The rubber membrane inside can degrade faster in areas with very hard water or if the valve was installed in a poorly ventilated space. If the valve is more than 15 years old and you are getting odour issues, replacing it is worth trying before investigating the pipework further.
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