You might not realise it, but an average family creates around 14 – 20 litres of moisture a day just by carrying out everyday tasks such as cooking, showering, even breathing. That moisture doesn’t just disappear which is why roof condensation solutions are so important. As it floats around your home, and if it finds its way up into your roof space, it can lead to condensation which can be the start of a long list of damp problems.
At LD Roofing, we see this all the time and offer roof condensation solutions. A roof might look perfectly fine from the outside, but when we look inside the loft space there’s damp insulation, dark stains on rafters or even rot setting in. The good news? All of this can be avoided once you have an understanding of why this is happening to your home and how to control it.
So, Why Does Condensation Happen in Roofs?
At the end of the day it all comes down to two things: temperature and moisture within your property. Warm air actually holds more moisture than cold air, so when the warm air in your home rises and meets the colder surfaces inside your roof, the moisture turns into the tiny droplets which we call condensation.
To put it simply at around 20°C, warm air can hold around 17 grams of water vapour per cubic metres. In comparison, a colder roof space which is around 10°C for example can only hold at maximum 9 to 10 grams of water vapour.
That extra 8 grams of moisture has to go somewhere, and it usually ends up on the underside of your underlay or on wooden timbers.
Older houses often got away with this because their walls, windows and roofs “breathed” a little through natural ventilation such as gaps and imperfections that allowed air to escape. However today’s homes are built to be energy-efficient and air tight which traps heat in but the downside is they also keep moisture in. So without a proper ventilation system installed, that moisture eventually condenses inside the roof which leads to a range of problems that you will want to find solutions for as soon as possible.
That’s why Building Regulations (Part C) makes it clear that roofs should be designed to avoid condensation altogether. It’s not just a comfort issue, it’s about protecting your home’s structure.
When Should You Worry About Condensation?
A small bit of condensation in your roof during a very cold spell isn’t unusual. It can appear when heating is on full and windows are tightly shut. Usually, it’ll dry up within a few days as the weather changes.
The problem starts when the moisture doesn’t go away, especially in the winter months. Persistent dampness from condensation can soak into insulation and timbers, leading to:
- Mould and mildew growth
- Decaying woodwork or weakened rafters
- Water marks on your ceilings
If left unchecked, that moisture can cause serious damage both to your roof and your home’s overall health so if you have any concerns it’s best to get it checked by professional roofers before it gets worse.
Understanding Roof Condensation Solutions for Modern Homes
There are really two sides to tackling condensation:
- Keep warm, moist air out of your loft.
- Give your roof space a way to breathe.
Let’s take a look at both.
1. Reduce Moisture and Air Leaks
Start by cutting down how much moisture escapes upwards. You can:
- Open windows when cooking or showering.
- Using extractor fans where possible.
- Avoid drying your clothes indoors.
The next step from here is making sure the ceiling below your roof is well sealed. Warm air can sneak through the smallest of gaps common places include loft hatches, light fittings or pipework.
Warm air can sneak through the tiniest gaps for example around loft hatches, light fittings or pipework. Having a well-sealed ceiling doesn’t just help with condensation it will also keep your home warmer and more energy-efficient which in turn will save you money in the long run.
2. Make Sure the Roof Can Ventilate
Even with good sealing, some moisture will always get through and that’s nothing to worry about as long as it can escape. When your home has effective ventilation it will let fresh air move through your loft space and carry moisture out before it has the chance to change into condensation.
The right ventilation depends on your roof type. BS 5250 gives the standards for this whether it’s a warm roof (where insulation follows the roof slope) or a cold roof (where insulation sits flat over the ceiling).
At LD Roofing, we always plan ventilation into every job from the start. It’s far easier (and cheaper) to get it right during installation than to deal with damp issues later.
The Different Ways to Ventilate a Roof
There are a few types of roof vents, and often the best setup for properties is a mix of them:
- Eaves vents sit along the roof edge, pulling fresh air in.
- Ridge vents are fitted at the highest point of the roof to let warm air escape.
- Tile or slate vents are more discreet options that can blend into the roof surface.
When used together, these different roof vents can create a flow of air from the bottom of your room to the top, this is known as cross-flow ventilation.
For most cold roof spaces, a continuous ventilation gap of at least 7mm at the eaves is a good minimum, especially when using a vapour-permeable underlay.
Also it is worth noting that different circumstances and situations can then impact the effectiveness of the ventilation for example if your home is connected to another building or if the loft is fully boarded out. In these scenarios, its common that extra vents or systems might be needed as further solutions to reduce roof condensation. But don’t worry, at LD Roofing our expert team are skilled in assessing what needs to be done to provide your property the best solution.
How Underlays Help as a Roof Condensation Solution
Condensation usually forms on the underside of the underlay within roofs, so the type you use really matters to ensure your home is protected.
Non-Breathable Felt (Type 1F)
This old-school felt roofing has been around for decades. It’s excellent at blocking water but the down side is it doesn’t let moisture escape. If you decide to use this, having a good ventilation system is essential to make sure that any moisture does not get trapped.
Vapour-Permeable Membranes
These are the modern go-to choice. They allow water vapour to pass through while still keeping out wind and rain so this choice is great at letting moisture out without letting water in.
Just remember with this type of membrane, they must be installed correctly. They’re not meant to be laid like old felt. Many need to be taped and draped properly to work as designed.
Air-Permeable Membranes
Air permeable membranes are a newer type of roofing underlay designed to let both air and water vapour pass through the material. Unlike traditional felt and vapour-permeable membranes we have mentioned above, air permeable membranes allow a small amount of air through the roof layers. By having this natural movement of air, it helps to reduce the amount of build up of moisture as it allows the damp air to escape before condensing.
Getting Installation Right
Like with everything, even the best materials can fail if they are not fitted properly. We often come across roofs where the underlay has been left loose, or sometimes the joints haven’t been taped, letting wind-driven rain or dust get through.
A few quick pointers from the LD Roofing team:
- Always follow the manufacturer’s guide as underlays vary a lot.
- Tape and secure laps to stop flapping or water ingress.
- Don’t cut tiles too close to the underlay as dust can block breathable membranes.
- And remember, underlay alone isn’t a substitute for ventilation.
Protect Your Home with Expert Roof Condensation Solutions
At LD Roofing, we take a long term approach to every roof we work on. We don’t believe in quick fixes. Instead, we design roofs that balance insulation, ventilation and moisture control, giving your home a healthy, durable roof that long-term approach that will last for years.
We also work with British Standard-approved materials, so you can rest assured that all work carried out by us is done to meet and often exceed the latest industry standards. Whether you’re in need of a new build, a renovation or sorting out damp in your loft space. We will make sure that your roof will perform exactly as it should so you can see the benefits.
Because at the end of the day, preventing condensation isn’t just about keeping your loft dry, it’s about protecting your home and your comfort all year and especially through the winter months. If you are in need of roof condensation solutions or any other roofing services, contact our expert team today by calling 01604 372453 or complete our online contact form to get a free quote for your property.
