Roof felt is a durable, waterproof material used as an underlay for flat and pitched roofs. It provides a protective barrier against rain, wind, and moisture, helping to prevent leaks and timber damage. Typically made from bitumen and reinforcing fibres, it adds strength and longevity to your roof structure.
To install roofing felt, start by preparing a clean, dry, and stable roof surface, removing any old felt, nails, or debris. Roll out the first underlay layer from the lowest edge and secure it with nails, then apply a second underlay layer with adhesive, offsetting joints from the first. Finally, add the top bonded or mineral layer, install edge flashing and trims, and check for gaps or creases to ensure a watertight, durable finish.
Here is how to install a roof felt in Cumbria:
1. Prepare Your Roof Surface: The first step is to prepare your roof surface. Clear away old felt, nails, dirt, and debris. Ensure the roof deck is dry, stable, and free from rot or moisture to give the new felt a solid base for long-lasting protection.
2. Lay the First Underlay Felt Layer: Next, roll out the first underlay felt starting from the lowest edge of the roof. Cut it to size and secure it with nails spaced evenly, avoiding the edges, to create a stable initial barrier against wind and rain.
3. Lay the Second Underlay Felt Layer: Apply a second underlay layer using adhesive, making sure the joints do not align with the first layer. Smooth out any air pockets and ensure the layer settles properly to reinforce waterproofing.
4. Apply the Top Bonded Felt Layer: Place the final mineral or bonded layer over the second underlay. This layer adds durability and forms the main line of defence against heavy rain, wind, and other harsh weather conditions.
5. Install Necessary Edging: Fit flashing, verges, fascia boards, and arris rails along the roof edges. Proper edging directs water into gutters and prevents rain from seeping behind the felt, protecting the roof structure.
6. Add the Finishing Touches: Finally, inspect the roof for gaps, creases, or areas that need extra adhesive. Ensure all trims and gutters are properly fitted for a neat, watertight finish and long-lasting protection.
1. Prepare Your Roof Surface
Before laying any felt, the roof surface must be clean, dry, and free from debris. In Cumbria, damp conditions can make timber surfaces particularly vulnerable to decay, so inspect for signs of rot or moisture damage.
Remove old felt, nails, and adhesives.
Repair or replace any damaged wood, especially on older cottages.
For new roofs, use exterior-grade plywood or waterproof chipboard for stability.
Ensure the deck is dry and dust-free for the felt to adhere properly.
Proper preparation is the foundation of a durable felt roof and reduces the risk of leaks during Cumbrian storms.
2. Lay the First Underlay Felt Layer
Start at the lowest edge of your roof, rolling out the first felt sheet.
Cut to size carefully and align precisely.
Nail with clout nails spaced evenly (approx. 75mm apart) without over-driving near the edges.
This underlay layer acts as your initial barrier, protecting timber from rain and wind. For homes in Kendal or Ambleside, where wind-driven rain is common, a well-laid first layer is crucial to prevent water ingress.
3. Lay the Second Underlay Felt Layer
The second layer bonds over the first using a suitable adhesive:
Avoid overlapping joints in the same position as the first layer.
Apply adhesive gradually, smoothing out air pockets and creases.
Install gutter drip trim at this stage to ensure water runs into gutters, protecting both roof and walls.
Two underlay layers enhance waterproofing and add durability, especially important in coastal towns like Whitehaven or Workington, where salt-laden winds can accelerate wear.
4. Apply the Top Bonded Felt Layer
The final mineral or bonded layer provides extra protection:
Adhere it carefully over the second layer with a high-quality adhesive.
Ensure full coverage without gaps.
This layer is what you see on the finished roof and provides the main line of defence against Cumbria’s heavy rainfall.
5. Install Necessary Edging
To prevent water ingress at the roof’s edges:
Fit flashing and verges along the perimeter.
Use fascia board upstands or arris rails where necessary.
Proper edging ensures rainwater is channelled safely into gutters rather than behind roofing sheets, reducing the risk of leaks and timber decay.
6. Add the Finishing Touches
Inspect the entire roof for gaps, air pockets, or areas needing extra adhesive.
Smooth out creases and ensure all edges are secure.
Check guttering and trims are correctly fitted.
A final inspection is particularly important in rural areas like Keswick or Windermere, where roofs often face more exposure due to open landscapes and fellside winds.
What are the Common Mistakes to Avoid When Installing Roofing Felt in Cumbria?
Avoiding the following mistakes ensures a long-lasting, watertight felt roof capable of withstanding Cumbria’s challenging weather.
Skipping surface preparation, especially drying timber before installation.
Aligning joints of consecutive layers directly on top of each other.
Neglecting edge flashing and drip trims.
Rushing adhesive application, causing air pockets or poor bonding.
Preventative Tips for Cumbrian Roofs
Simple preventative care can extend the life of your roofing felt and help avoid expensive repairs in the future.
Regularly inspect flat roofs, particularly after storms.
Remove moss or debris promptly.
Check gutters and trim for blockages to prevent water pooling.
Apply a maintenance coat or sealant if required.
What Are the Benefits of Using Roofing Felt?
Roofing felt provides a reliable waterproof barrier, protecting flat and pitched roofs from rain, wind, and damp, essential in Cumbria’s often wet and windy climate. It helps prevent timber decay and water damage, extending the lifespan of your roof while giving you peace of mind during heavy storms.
In addition to protection, felt is cost-effective and relatively easy to install, making it suitable for both DIY projects and professional roofing jobs. It also adds an extra layer of insulation and, when combined with proper edging and flashing, ensures water is channelled safely into gutters without seeping into the roof deck.
How Long Does Roofing Felt Last?
The lifespan of roofing felt depends on the type used, quality of installation, and local weather conditions. Traditional felt can last 10–15 years, while modern mineral or bonded felt layers may last up to 20 years when installed correctly and maintained regularly.
Regular inspection is key in areas like the Lake District or coastal towns such as Barrow-in-Furness, where harsh weather can accelerate wear. Checking for moss, debris, or small tears every few months helps identify minor issues before they become costly repairs.
Can I Install Roofing Felt Myself?
Yes, roofing felt can be installed by confident DIY enthusiasts, especially on small flat roofs, sheds, or extensions. The key is careful preparation, proper alignment of layers, and following step-by-step instructions to ensure a watertight finish.
However, larger roofs or properties in exposed locations may benefit from professional installation. Experts bring the right tools, adhesives, and experience to deal with tricky areas, steep slopes, or complex roof structures, reducing the risk of mistakes that could lead to leaks.
How Do I Maintain a Felt Roof in Cumbria?
Maintenance involves regular inspections for tears, air pockets, or loose edges, particularly after storms. Cleaning debris, leaves, and moss ensures water flows freely into gutters and prevents water pooling that can damage the felt.
Additionally, applying maintenance coatings or sealants can extend the roof’s lifespan. Ensuring trims, flashings, and fascia boards remain intact will keep the roof secure against Cumbria’s frequent rain and strong winds.
For homeowners who want expert guidance or professional installation, Westmorland Roofing provides trusted services across Cumbria, including Carlisle, Kendal, Penrith, Keswick, Windermere, Ambleside, Barrow-in-Furness, Whitehaven, and Workington. With over 9 years of experience, they understand the local weather, traditional building materials, and modern roofing solutions, ensuring every felt roof is installed to last.
Whether you want advice, a free inspection, or professional installation, Westmorland Roofing offers a friendly, reliable service to protect your home from Cumbria’s unpredictable weather.
