Felt for Garage Roof – Why Modern SBS Torch-On Systems Outperform Old Felt
When I’m called out to leaking outbuildings in Brighton, Hove, or Worthing, the problem is almost always the same: old mineral felt that has reached the end of its movement capacity. Traditional coverings simply weren’t designed for the thermal expansion and contraction we see in modern UK conditions, especially when choosing the right materials for outbuildings that are fully exposed to the elements.
For these structures today, I consistently specify Tecnatorch SBS Torch-On Mineral Felt Charcoal because it behaves completely differently from the oxidised bitumen products used 30–40 years ago. It’s flexible, UV stable, and crucially, it can move with the structure instead of fighting against it, making it one of the most reliable technical repairs for storage units in Hove and the surrounding areas.
Why Old Felt Systems Fail on Garages
Most external buildings constructed in the 1980s and 1990s used basic built-up felt systems. These materials become brittle over time due to UV degradation and repeated thermal cycling. When renovating a storage structure in Sussex, where coastal winds and salt exposure accelerate ageing, I often see:
- Surface cracking from thermal stress
- Blistering caused by trapped moisture and poor ventilation
- Splitting at joints due to capillary water ingress
Once this starts, water doesn’t just sit on the surface – it tracks through overlaps and penetrations, often damaging timbers before you even notice an internal leak.
Why SBS Torch-On Felt Performs Better
The key difference with SBS-modified bitumen is elasticity. The polymer modification allows the membrane to expand and contract with temperature changes without fracturing. This is essential for uninsulated structures which are typically exposed to rapid heat gain and loss.
Tecnatorch SBS Torch-On Mineral Felt Charcoal also includes a mineral cap sheet that provides UV protection, meaning the system doesn’t degrade in the same way older exposed materials do.
Two-Layer System Explained
When I install a proper waterproofing system, I always use a two-layer build-up:
- Base layer: a smooth underlay that accommodates structural movement
- Cap sheet: a mineral-surfaced layer that protects against UV radiation and mechanical wear
This layered approach is critical. Timber decks move daily, and a single-layer system simply cannot absorb that stress without splitting.
Installation Method – Why Torch-On Matters
The system is applied using a gas torch, bonding the bitumen directly to the prepared deck. This creates a fully adhered membrane with no loose laps or weak adhesive points. Done correctly, it eliminates wind uplift issues and reduces the risk of capillary water tracking between layers.
The quality of finish is also significantly better than cold-applied alternatives. A properly torched SBS system flows into joints, sealing them as a continuous waterproof barrier rather than a patchwork of glued seams.
Common Failure Points I Still See
Even with modern materials, poor installation causes most problems. The issues I regularly repair include:
- Inadequate substrate preparation leading to poor adhesion
- Incorrect detailing at wall abutments and upstands
- Single-layer installations used to cut cost
In many cases, especially on older blocks, I recommend a full replacement rather than patch repairs. If water has already entered the deck, the structure is usually compromised.
Professional Garage Roof Replacement
As an experienced local tradesman, I treat every replacement as a complete system – not just a surface layer. That includes checking timber condition, correcting falls for drainage, and ensuring all edge trims and flashings are mechanically fixed and sealed.
You can see typical project costs and options here: detailed price estimate for your project. For more complex structures, I also apply the same SBS torch-on methodology across extensions and outbuildings where movement is a factor.
Conclusion – Why I Specify SBS Felt for Garage Roofs
In practice, a roof isn’t just a waterproof lid – it’s a moving structure exposed to constant thermal cycling. That’s why I rely on SBS-modified systems like Tecnatorch. They don’t just cover the building; they accommodate how the structure behaves over time.
If you’re dealing with leaks, bubbling, or visible cracking, it usually means the system has already lost elasticity. At that point, a proper replacement is the only long-term fix. You can get an instant idea of cost and options using my online calculator, which gives a clear, no-obligation estimate in under a minute.