Breather Membranes: Complete Guide

Insulation, Membranes & Felts
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Breather Membranes: Complete Guide

Membranes see use on buildings up and the UK, offering a variety of benefits not least of which is helping to ensure our roof's longevity. Breather membranes are one such example. They are one of the most important elements of any roof, and as such, it is important to know as much about them as possible, whether that be related to installation and ensuring your membranes have been applied properly, or the key benefits to having a fully functioning breather membrane system.

We’ve put together this guide to help bring you up to speed on some of the most important facts about roofing membranes. We’ll look at how they work, touch on the installation process, the cost of the average breather membrane, and more. So, if you want to learn more about breather membranes and what they can do for you and your roof, read on to find out about these fantastic products.


What is a Breather Membrane?

Despite their name, a breather membrane is not just present in a roof to help it breathe. In fact, in many cases, a building would remain breathable without the membrane in place at all. What makes the breather membrane so important are the benefits the roof enjoys while still being allowed to breathe thanks to the membrane.

Breather membranes have been designed to allow structures that have been insulated to continue to release any excess moisture vapour into the atmosphere. This allows other parts of your roof or wall to remain dry, functional, and free from the risk of water or vapour-induced damage. At the same time, it also serves as another layer of protection within your roof, preventing ingress of dirt, rain, debris, and in some cases pests such as mice, wasps, and bats.

How do Breather Membranes Work?

As mentioned above, breather membranes are resistant to elements such as water, snow, and dust. However, they are also air permeable. They function best in roof structures (or alternatively external walls) where the chosen cladding material may prove not to be totally water-tight or resistant against moisture or dust ingress. The best example of such a material – and one of the most popular roofing materials on the market – is the roof tile.

With the membrane located on the cold side of the insulation, it is able to prevent moisture that may enter the external cladding from making its way further into the roof. While doing this, however, the air permeability of the membrane allows for ventilation to continue, reducing – and in some cases eliminating – the appearance and spread of condensation.

How Easy is it to Install Breather Membranes?

Breather membranes can, in theory, be installed fairly easily. However, as the installation is part of the larger, more complex roof constructing process, you may find it simpler to ask a professional to install it for you, particularly if you are already looking at – or in the process of – having your roof built or repaired by experts.

Breathable membrane installation is usually carried out via the following steps:

  1. Find out if your breather membrane is UV resistant – if it isn’t, you will need to lay one of these layers first between the eaves of your roof and across the guttering.
  2. Lay the membrane with the printed side facing upwards. This will prove clearer on some brands than others, but the vast majority of manufacturers today apply an obvious printed side to their membrane.
  3. Ensure that your breather membrane overlaps your UV resistant layer ending at the guttering. Again, if your membrane is UV resistant you can skip this step.
  4. Ensure there is slack as you lay your membrane across your roof. Try to get the drape to be around 1cm – 2cm.
  5. The breather membrane can be fixed into place by applying nails where the membrane runs over the battens. If none are present, add a batten yourself where the lengths overlap. It is important to ensure the tiles do not touch the felt.
  6. Once your first membrane length has been laid, you can start to work upwards from the bottom of the roof, making your way to the top and ensuring that each membrane length overlaps by 1cm – 2cm each time.
  7. Wherever the membrane meets a chimney or similar protrusion, cut it to create flaps and applying these so that the overlap goes up flush against it.

Are Breather Membranes Airtight?

A common question asked about breather membranes is whether or not they are all airtight, and the answer is that it depends on the particular membrane. Many manufacturers of breather membranes will offer different models, which will prioritise different features such as UV resistance and, of course, an airtight structure. There are both airtight and air open membranes available on the market.

It is important to plan what type of breather membrane you will use because it may alter the need for other items and features on and within your roof. Airtight breather membranes are excellent at protecting from draughts and wind, as well as several temperature conditions, but it is not recommended to rely on them for ventilation alone – using vapour permeable membranes or another form of roof ventilation will allow potentially harmful vapour to escape the roof effectively.

How Much Do Breather Membranes Cost?

Breather membranes can vary greatly in cost, with multiple factors considered when prices are set. These include:

  • Size of membrane
  • Manufacturer
  • Features such as UV ray resistance
  • Accessories provided such as fixings

Thus, as you shop around for membranes, you’re likely to find a wide range of prices. You will need to look into each item, explore the benefits and features, and work out if it is the right membrane for you considering what you get for the price.

A simple breathable membrane without the majority of special features and around 50m in length will set you back about £30. At the other end of the scale, Larger membranes with features such as UV resistance or additional thickness, coming complete with fixings and accessories, can cost around £200. Of course, there is also a happy medium between the two, with quality choices available from brands such as Novia for around half of this.

What are the Benefits of Breather Membranes?

As mentioned throughout this guide, there are many benefits to breather membranes. Their key function is allowing your roof to breathe while simultaneously protecting it from multiple threats, both natural and artificially induced. These include:

  • The appearance and spread of damp patches
  • Rot and decay
  • Damage to surface finishes
  • Sub-standard or otherwise disappointing performance of insulation
  • Slip hazards
  • Pest intrusion
  • Damage to electrics

And there are many more besides. All of these are much more likely to occur without breather membranes, and while the membranes may not totally eliminate these problems from occurring, they will certainly help to dramatically decrease likelihood and frequency.

Have More Questions About Breather Membranes?

And there you have it – some of the most important things to know about breather membranes. You will hopefully now have a clearer idea of the key facts and benefits on the subject of these vital roofing products. Simply call us on 01295 565565 or chat to us directly using the chatbox below.

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