Your Specialists in Eradicating Condensation & Mould

Our Positive Input Ventilation Units (PIV)

  • Will eradicate loft/roof space condensation
  • Prevent mould and damp throughout your home
  • Combat Asthma and Allergies through High Air Filtration
  • Suitable for all properties


Why choose Attic Alert for PIV installation - Loft mounted Positive Input Ventilation systems  PIV, are widely acknowledged as being the most efficient and cost effective way of eradicating condensation and mould in residential properties. Attic Alert have been specialising exclusively in loft work for 20 years. With our wealth of specialist experience we're the No1 company to choose. We offer a FREE LOFT HEALTH CHECK where we properly assess all aspects of your roof space, not just the best location to fit your PIV. Here's what you can expect from Attic Alert

  • Supplying the best heated loft mounted PIV units on the market
  • Professional installation with our "No Mess Guarantee"
  • We can provide safe access to your PIV with our range of easy to operate loft ladders
  • We will advise on loft insulation levels in your home and can install more if required
  • See if poorly fitted old insulation is blocking your eaves ventilation
  • We'll check your loft hatch for thermal efficiency and can replace if necessary
  • Check your loft is adequately ventilated and bathroom extractor is vented externally
  • Check for air leakage from downlights and fit light hoods if required
  • Supply and fit NHBC approved raised loft boarding for both access and storage

We can deal with all the potential aspects of your work, while you only need to deal with one, long established, family business - start to finish

Do PIV units work? The short answer is yes, and their results are truly transformational. Eliminating damp, condensation and black mould problems in properties where the owners had previously thought the issues were untreatable. A few weeks after installing PIV units, their homes were given a new lease of life. PIV units create air flow through positive air pressure. Cold draughts in your house follow the same patterns as any wind current throughout nature - going from areas of high air pressure to areas of low air pressure. So if the air pressure inside your house is lower than outside, cold air will be pulled in. While stale, moisture heavy air stagnates and doesn't move. When humidity (moisture levels) in your house are too high it will collect on cold surfaces, causing condensation, damp and mould - all of which can negatively impact your health and damage your property. By increasing the air pressure in your house, moisture laden 'stagnant/humid air' will be pushed outside through existing micro vents associated with the properties construction , along with all the moisture, VOCs, pollens, pollutants and allergens it contains. This is exactly what PIV units do by constantly ventilating your home with fresh purified filtered air drawn through your loft space vents creating positive air pressure. The science is straightforward and the results are phenomenal. You'll notice an improvement in air quality as soon as your system is turned on. Over time your condensation, damp and mould problems will be dealt with too - if not entirely eliminated

What are the benefits of having a PIV unit installed? Our priorities will always be your health and wellbeing and protecting your home from potentially very expensive repairs caused by condensation and mould issues. Below we've listed a few of the reasons why you should choose to have a PIV unit installed by Attic Alert.

  • Cost effective solution for treating condensation
  • Eliminates damp and mould issues in most properties
  • Improves air quality throughout your home
  • Reduces odours, VOCs and pollutants that enter the house
  • Reduces and controls humidity levels in your home
  • Clinically proven to reduce dust mite allergens
  • Alleviates asthma symptoms through air purification
  • Filters pollen particles for hay fever sufferers
  • Create and Maintain a Healthy Home Environment
  • BBA approved

The most common causes of condensation and mould are a result of:

  • High Humidity levels
  • Poor Ventilation
  • Warm air leakage into the roof space

Humidity - Research has shown that the average family of four can generate over 14 litres of water vapour in just one day, through common activities such as washing, cooking, boiling the kettle and drying clothes. Even just breathing releases moisture into the atmosphere. All that moisture has to go somewhere when trapped inside your home, and it can often cause or exacerbate health issues within your family, such as asthma. It can also often cause very significant structural damage to your home resulting in expensive remedial work - still without addressing the fundamental cause, which Attic Alert can deal with in just one visit.

Poor Ventilation - In recent years the drive to maximise energy efficiency and protect against heat loss in your home has been done at the expense of failing to ensure adequate air flow and ventilation in your house. Leaving properties with absolutely minimal ventilation in an effort to ensure warm air stays inside at all costs. Those 'costs' could well be the health of your family and structural damage to your property. Who wants to open a window on a cold day while you've got the heating on? However, the simple fact is that energy efficiency and ventilation have to go hand in hand. It's crucial that you ensure adequate ventilation throughout your home - And it all starts in the roof space. Even with the installation of our market leading PIV systems we'll always carry out a FREE LOFT HEALTH CHECK as it's essential to ensure that your roof insulation, ventilation and air leakage are properly addressed. Often DIY loft insulation has been pushed into the eaves of your roof - restricting air flow - We can remove this for you as this really is a job best left to the professionals as this part of the roof space is particularly inaccessible and potentially dangerous  If you haven't already got vented soffits or ridge tiles we can install felt lap vents for you too, particularly effective in older properties with non breathable bitumous roofing felt material. At  Attic Alert, with our specialism and experience in loft boarding, insulation and attic access, we can take care of all of these issues (and more) for you in just one visit.

Warm air & humidity leakage into your roof space -  First we need to eliminate or absolutely minimize warm air leakage into the loft. These are the first questions a homeowner should ask. Is my loft hatch properly insulated and air tight? Is my bathroom extractor fan in good repair? Are the outlet hoses properly connected and externally vented? Are there any holes or tears in the outlet hose which cause it to leak humid air into the loft? Are my upstairs downlights properly covered to prevent heat loss - ideally these should be replaced with modern LED fittings which can be properly sealed - And lastly, Is my loft properly ventilated to allow adequate airflow? When the colder months arrive and temperatures go below zero, the moisture and humidity leaking into your loft will accumulate and condense on the underside of your sub zero temperature roofing membrane. Depending on the temperature, ventilation and insolation (i.e. can the sun get to your roof) you will have either frost (known as ice damming) or water collecting. If you're baffled by frost and condensation only seeming to form on one side of your roof, you're probably looking at the North side. The sun will often warm the South side enough to thaw and evaporate moisture effectively but still leave it coated on the North side. The problem then is that while insolation has dealt with South facing frosts through evaporation, the unintentional consequence is that your North facing roof space has been warmed up enough to melt the ice - but NOT enough direct heat for effective evaporation. Hence the indoor winter waterfalls. Adequate ventilation, prevention of air leakage, proper roof insulation and having us install one of our state of the art heated PIV units will not only eliminate this, but also cure your entire property's condensation and mould problems.

What causes condensation and mould in my loft?  - To answer this question we have to look at your property as a whole, not just the roof space. Having worked in lofts for 20 years it's common for us to find evidence of condensation and water damage in a property that the homeowner isn't aware of. Early indicators to be alert for downstairs are condensation on the internal surface of your windows and checking behind large items pushed against walls, or built-in wardrobes to ensure there is no mould growth, dark patches or feeling damp to the touch.


Browse our collection of frequently asked questions for answers to your queries.

Why is there frost and ice inside my roof space? +

What can I do to stop mould and condensation? +

Are PIV systems noisy and expensive to run? +

Do PIV units make the house cold? +

How does a PIV unit work? +

Do PIV units stop mould? +

Is getting a professionally installed PIV unit worth the money? +

Can I totally eradicate condensation and mould from my home? +