Loft Vents Reduce Condensation

Loft Vents Reduce Condensation: Ashbrook Roofing Supplies

Here at Ashbrook Roofing Supplies, we are all about solutions for homeowners. Today’s modern living spaces prioritise energy efficiency above all things. However, sometimes one solution can create another problem.

Loft Vents are an affordable solution to reduce condensation

Condensation in your house can be one of those problems partly contributed to by modern energy-efficient homes.

Condensation builds up during everyday living, people and pets breathe out water vapour, but only small amounts, Kettles, Washing Machines, damp washing drying, Tumble dryers, kettles, Cooking baths and showers all contribute to the daily output of water vapour in the everyday modern home.

Hot air, of course, rises, and all that water vapour in the air has to go somewhere. It goes up and can find its way up into your loft space.   Modern lofts are comparatively cold compared to the rest of your house because they are often very well insulated.

So once the water vapour enters your loft space, which it does through wall cavities, gaps in the ceilings and loft hatches,  it then settles on surfaces as condensation.   Most of us live our lives unaware that this is even happening.  Well, it might be happening in your house, right now. It’s certainly worth checking today!

We could talk about all the ways condensation could create problems for you but instead, we would rather just show you an affordable method that you can use to reduce the build-up of condensation in your loft.

We recommend that you buy loft vents that are small and lightweight, they are really easy to fit and they create a very quick and easy solution to your condensation worries.  The type of vent that we recommend are called Felt Lap Vents. They can be fitted by you, without any expert help. A couple of popular types are Manthorpe and Hambleside Vents.


Manthorpe Felt Lap Vent. Perfect for Loft Ventilation.
Manthorpe Felt Lap Vent. Perfect for Loft Ventilation.

Quick Guide to fitting Lap vents

Because these events are lightweight they won’t cause damage to a membrane, as long as you’re careful. Just turn it’s over, you can see the vents that sit directly between any overlaps and underlaps in the under sacking in your loft. The vents on the bottom will be unseen on install and poke through into the gap between your roof covering and under sarking

The springy little hooks fasten the vent in place.

The Lap vent is inserted between the overlapping under sarking. It really doesn’t matter whether your loft has a membrane or the older black bitumen felt. Once in place, the vent connects air from inside your roof space to underneath the roof tiles or slates. Now, when the wind blows and moves air directly over the face of the roof it will enter the bottom of the lap vents and flow into your loft space.

Many modern houses from the 1970s onwards were built were with no dedicated roof ventilation.  It’s worth noting at this point that even if you don’t discover any serious problems with condensation or heat build-up..Lap vents are extra insurance to be sure your home stays free of such problems.

Take your time when fitting the vents, you may have to give them a wiggle until they slide into place. Once in place, the vents are almost unnoticeable and they don’t sit too proud of the under sarking either, this helps to avoid the risk of tears and unlike some other systems on the market, you won’t have to make any cuts to your undersarking or felt.

We recommend buying a pack of Felt Lap vents to ensure good even distribution of airflow through your loft.  As long as you fit them evenly spaced you should reduce condensation in no time, as any moisture is evaporated into the inflowing air.

fit 5 vents on each elevation of your roofs at slightly staggered positions. this helps better air circulation.  By staggering the positions of the vents the wind can’t simply blow in one, and out of the other.  For further information, please click the link below.

Product links


Why Loft Ventilation is Important

Why Loft ventilation is so important: Ashbrook Roofing Supplies

We usually only consider attic ventilation only when there is a problem, but because most of us only go up into the attic or loft a few times every year. Most of us don’t realise that there is a problem until it’s quite a problem.

On one of our infrequent trips to the roof space, we might notice the suitcases were covered in mould…or perhaps just wet.  Further inspection might reveal that it’s not just the cases, but the roof felt, ceiling beams, etc.
If so, you need to take action now!

Condensation in your loft not only damages everything stored there, but can also penetrate your insulation and reduce its efficiency. Also, if the insulation becomes damp, it will be difficult to dry. and could even permeate to the ceilings below.

When very bad, condensation saturates the insulation it will show a damp spot on the ceiling below. Now, most peoples thoughts might be that the roof is leaking…and it’s certainly worth checking. if in doubt get an expert to check your roof.

If the roof looks good, it is worth making sure that there is sufficient ventilation to avoid possible problems along the way.

If you have any wet, discoloured patches on the ceiling, it’s worth a trip into the attic to try to find the source.  the stains occur as the moisture drips onto the dusty attic insulation

Loft Ventilation

Why has attic ventilation been a hot topic in recent years? Well, the answer is simple..In the past (up to about 20 years ago) Our homes were relatively poorly insulated.  Therefore,  any build-up of water vapour was evaporated by the fresh air coming through these airflows. Meaning that condensation would rarely build up indoors.

Today houses are much better insulated,  but this can create a problem too.  Pre insulation, lofts used to get a lot warmer than they do today.  Heat would rise inside houses rises and water vapour in the air would be dispersed by evaporated by natural draughts to the loft space.

Eco-friendly, but not damp lofts

We all want to reduce heating costs and keep our homes warm for as long as possible. So we Insulate walls and attics and insert modern windows and doors to save money and be more eco friendly.  These measures may be good at lowering the operating costs of our home and keeping it warm longer. However, all this extra insulation means that the attic (above the insulation) gets colder because the heat is trapped in the room below.

Also, most people don’t install moisture barriers when they add insulation.  so any gaps in the houses, wall spaces and loft hatches still allow moisture to enter the attic.

Moisture can penetrate the newly insulated attic and come into contact with very cold surfaces.
Water vapour entering the loft increases the risk of condensing at the inside of the roof slope or other cold surfaces such as water tanks. To reduce the chance of condensation, you need to increase ventilation in the attic to try to remove the water vapour that is generated before condensation occurs.

Why doesn’t standard ventilation work?

Ventilation of the roof built into your home would have been sufficient during construction.
However, if you add something that may cool the surface of the loft (such as adding more insulation ) or if you reduce the efficiency of existing ventilation (partially or completely block existing vents), which people think are outdated, we need to think again.  Make sure the existing vents are not blocked.

Common things that can increase the risk of condensation in the loft:

  • Placing insulation on top of the existing vents.
  • The water tank inside the loft is hot and water vapour enters the loft (this is the job of the plumber).
  • Excessive water vapour from your home rises into the attic. Perhaps through a gap around a light, toilet,  loft hatch.
  • An Increased insulation level of the attic without providing extra ceiling ventilation. Different types of loft ventilation:

Adding Loft Ventilation

So now that we have identified the issue, It’s time to take action. One of our most popular products for addressing the issue of loft ventilation are Felt Lap Vents.   Felt lap vents are a low cost, easy to install solution to ventilating your attic or loft.

Condensation problems in the loft can be resolved relatively easily by adding some lap vents to the attic.

Manthorpe Felt Lap Vent. Perfect for Loft Ventilation.
Manthorpe Felt Lap Vent. Perfect for Loft Ventilation.

Don’t ignore any condensation you may encounter, that will just lead to the problem getting worse, the longer you leave it. Try to figure out where the water vapour is coming from. It would be beneficial if it could be prevented from entering the loft at all, but if you can’t adding Felt lap Vents is a cheap and simple solution.

Learn more about Felt Lap Vents.

Felt Lap Vent, Loft Vents and other Loft Ventilation Products

Felt Lap Vent, Loft Vents and other Loft Ventilation Products.

Part 3 in a series of guides about how to stop condensation in loft space, attics and roofs.

This article focuses on:

In this final section of our complete guide on how to stop condensation in loft spaces, we will give you all the tips and professional advice you need to banish condensation from your home.

What causes condensation in your attic?

Commonly found in bathrooms after a long hot shower, or kitchens after boiling the kettle, condensation is a daily occurrence in most homes. In some instances, it doesn’t cause any issues at all. But if it is left to build up in your attic or loft, it could lead to both serious health problems and structural damage.

So how does condensation occur? Well, put simply, condensation forms when warm air comes into contact with cold air or cold surfaces. The water vapour within the air liquefies to form water droplets or dew. These droplets cling to walls, windows, furniture, ceilings, lofts… just about any surface, and this is what we refer to as condensation.

It’s easy to ignore condensation in the loft or attic. Most people only visit their attic once or twice a year. The weeks running up to and following Christmas is one example as many people visit their lofts to bring Christmas decorations down from storage.

However, if you do spot it, it’s important that you take quick action to stop in turning into a major issue.

Loft vents come in all shapes and sizes. Our top 5 Loft Ventilation Products to stop condensation in your attic are listed below:

Felt Lap Vents
(DIY solution for modern and period properties):

Felt Lap VentsFelt Lap Vents are considered by many as the most popular and easy-to-fit products available on the market today. Inserted on the inside of the roof, they are a DIY product that can be easily and cheaply installed. They are extremely effective at treating condensation problems in attics and lofts.  Manthorpe and Easy Vents for Lofts are widely considered to be the best on the market.

Manthorpe Felt Lap Vent.

Specifically designed to improve ventilation in existing loft spaces, Manthorpe lap vents are manufactured from robust polypropylene plastics. Designed to slot right into your breather membrane or roof felt, they are simple to install. Each vent is equipped with 3 felt clips to keep it securely in place and generates up to 3,000mm2/m of ventilating airflow.

The Manthorpe Vent can be fitted to any loft with joists ranging from 400mm to 600mm, and they are fully recyclable after use.

EasyVent for Lofts.

The EasyVent is both innovative, inexpensive and inconspicuous. Just like Manthorpe vents, they are installed on the inside of the roof, in between the overlap and underlap of the felt lining or membrane.

Each EasyVent Loft Vent comes with a spring attachment that you position inside the vent before installation to create an airflow outlet.  This allows warm, moisture-rich air to escape through the roof and instantly helps to stop condensation in lofts.  It’s such a simple solution, but it works.

Other Products to Help Ventilate your Attic.

There are many products available to help you stop loft condensation, and most of them are inexpensive. Remember that they require a lot more work to fit, and work is often undertaken on the outside of the building. Here is an overview of 3 other roof vents that may help you:

Roof Vents

(Fascia, Soffit and Eaves Panel Vents).

Roof vents are inserted into the inside of the roof, usually in the eaves. They improve airflow, aid ventilation, and prevent the build-up of condensation. Available in a variety of specifications, colours and sizes to suit every property. Roof vents are affordable, quick to install, and effective at reducing loft condensation in buildings of every size. They are best installed on new roofs or when an old roof is being refurbished.

Roof Tile Vents.

Roof tile vents are applied to the exterior of the roof, just like regular roof tiles. Each tile is fitted with an inconspicuous air vent that draws warm air up and out of the roof while keeping bugs and debris out of your roof space. Any rainwater entering the vent is funnelled straight back out onto the tile, and so your loft remains dry and condensation free. Roof tile vents come in various colours and sizes, so matching them up to your tiled roof is easy.

Slate Vents.

Products are also available for slate roofs in the form of slate vents. Compact, easy to install, and discreet, these vents are ideal for period properties and stone houses, where they promote airflow and keep roof spaces free from condensation. They slot in place just like regular roof slates and blend in seamlessly with the rest of the roof.

If you have damp in loft or attic and need advice, please contact the Roofing Specialist at Ashbrook Roofing Supplies. Alternatively, read our other articles in this series to find out more.