Recent Project in Keswick: Removal of 1970s Expanding Foam & Welsh Slate Re-Roof
At Cumbria Roofing, we pride ourselves on restoring and protecting the heritage roofs that make our region so special. Our latest project in Keswick has been a perfect example of the challenges—and rewards—that come with traditional roofing work.
The Property: 18 x 10 Welsh Slate Roof
This beautiful property featured an 18 x 10 Welsh slate roof, originally finished with high-quality natural slates. Unfortunately, like many roofs treated during the late 20th century, expanding foam insulation had been applied to the underside of the pitched roof—an approach that was common during the 1970s.
The Problem with Expanding Foam Insulation
Expanding foam was often promoted as a quick way to stabilise older roofs, bonding the tiles or slates together and preventing movement. While it may have seemed a good idea at the time, we now understand the long-term issues it creates.
Once applied, the foam significantly alters how a roof breathes. It disrupts ventilation and traps moisture, leading to:
- Condensation buildup
- Persistent dampness
- Black mould and fungal growth
- Timber decay
- Hidden structural deterioration
As moisture becomes trapped, the integrity of the roof structure declines—often out of view until major issues arise.
The Challenges of Foam Removal
Removing expanding foam is a difficult, labour-intensive process. It bonds aggressively to slate and tile surfaces, making separation without damage extremely difficult. In many cases, the removal process results in breakages or reveals extensive damage beneath.
This was true for our Keswick project. Despite working with great care, some of the original Welsh slates could not be saved due to the depth of the foam adhesion.
Our Work So Far
Our team has now fully removed the expanding foam, allowing the roof to begin breathing again and ensuring all hidden structural concerns could be inspected properly. Although we were disappointed to lose some of the beautiful original Welsh slates, the integrity of the roof must always come first—and the foam made their preservation impossible.
Next Stage: Re-Roofing
We are now moving on to the re-roofing phase, where we will be reinstating the traditional slate finish this property deserves. Our goal is to restore both the roof’s appearance and long-term performance, ensuring the home is safe, weatherproof, and breathable for decades to come.
