Flat Roof Waterproofing with Felt

Traditionally, felt membranes for waterproofing roofs involve a system where a layer of bituminous felt, rolled with bitumen or asphalt, acts as a protective barrier against water infiltration. This type of system, known as a built-up roof (BUR) or modified bitumen roof, is most suited for flat or low-slope roofs.

However, Carlisle® introduces a new and innovative solution: the SURE-MELT® bituminous system. This system offers several advantages over traditional felt membranes:

Triple Protection: SURE-MELT® boasts a three-layered system for unbeatable robustness and durability. It features two layers of hot-melt bituminous membrane, a reinforcement layer, and a protection sheet. This design is built to last the lifetime of the building.

Weatherproofing: This effective system not only shields your roof from water ingress but also prevents water from tracking beneath the membrane.

Fire Resistant: When used in specific roof specifications, SURE-MELT® can achieve a BroofT4 classification, unrestricted under national building regulations. This means it offers a high level of fire resistance.

Wind Uplift Resistance: The system bonds fully to the substrate, eliminating susceptibility to wind uplift.

Damage Resistance: While caution is advised to avoid puncturing from sharp objects or excessive loading, SURE-MELT® is a self-healing bituminous system, robust enough to withstand normal foot and construction traffic.

Low Maintenance: Regular inspections are recommended, following BS 6229:2018 guidelines, but overall maintenance needs are minimal.

Bituminous System Components

The SURE-MELT® system is a complete and reliable solution, ideal for inverted roofs, buried applications (including green roofs), and warm roof build-ups. Here's a breakdown of its key components:

Primer: A quick-drying bituminous primer applied to the substrate with a roller or brush to enhance the adhesion of the waterproofing membrane.

Reinforcement Fleece: A high-strength polyester fleece with a thermally bonded, point-embossed surface. This acts as a crucial reinforcement layer between the two SURE-MELT® bituminous layers.

Bituminous Compound: The core of the system, this polymer-modified bitumen compound is hot-applied in two layers. It provides a hardwearing, seamless waterproofing membrane with a minimum thickness of 6mm and permanent adhesion to the substrate.

SURE-MELT® CPS: A high-performance, polymer-modified bitumen, sand-faced protection sheet available in 2kg and 4kg options. This sheet is rolled into the hot-melt bituminous liquid membrane for complete bonding during the curing process.

SURE-MELT® CPT: A high-performance, mineral-faced protection sheet available in 2kg and 4kg options. Installed using a torch over the cured hot-melt layers, the underside features a heat-sensitive film for rapid torch-on installation.

SURE-MELT® CPM-5: This 5kg root-resistant protection sheet is ideal for green roofs and podium gardens. It contains a chemical root retardant, a polyester reinforcement carrier, and a charcoal slate mineral finish for additional root ingress prevention.

Delivery and Site Handling

• Bitumen compound comes in blocks on pallets.

• Protection sheets (SURE-MELT® CPT & CPS) are available in rolls of varying weights and lengths.

• Reinforcement Fleece comes in rolls.

• Primer comes in drums.

Refer to the product Safety Data Sheet (SDS) for proper storage and disposal of packaging.

Compound Melting

The compound is melted in a designated hot melt mixer/pot at a recommended temperature range (140°C to 190°C). Avoid exceeding 220°C. The molten product is applied using a squeegee or spreader onto the prepared substrate.

Installation Preparations

Pre-Installation Cleaning
Ensure the roof area is thoroughly cleaned, removing all debris, dust, laitance, and concrete splatter.

If the roof has experienced moisture, allow sufficient drying time before proceeding. Perform an adhesion test to confirm dryness.

Adhesion Testing
Conduct adhesion tests at designated locations to assess the suitability of the substrate for bonding with the waterproofing membrane.

Contact the Technical Department if encountering issues with adhesion during testing.

Bond Test Method

• Melt a small amount of compound as per instructions.

• Apply a thin layer (3mm) of the molten compound onto the primed area using a hand-held spreader.

• Embed a piece of Reinforcement Fleece into the hot compound and press firmly.

• Allow the entire area to cool before proceeding.

• Check adhesion by carefully folding back a loose edge of the fleece and pulling it horizontally. If the compound peels easily, the bond is not satisfactory and requires rectification.
  
  

After Successful Bond Test

• Repair cracks or weak areas in the substrate using an approved repair mortar.

• Use additional compound to fill minor depressions if needed.

• Wear appropriate personal protective equipment (PPE) when handling hot materials.

• Consult the Technical Department for specific details, safety precautions, and recommended tools.

• Once completed, lightly prime the area with Primer and allow it to dry before installing the membrane.

Detailing Work

General Considerations

• Ensure all surfaces are clean, dry, and free of irregularities before applying the compound.

• Transitions should be sharply formed without uneven surfaces or edges.

• Solid surfaces are required. Consult the manufacturer for guidance if encountering voids.

Applying the Compound

• Use a spreader to apply a line of the compound at the base of the detail.

• Pull the material up the vertical surface to the desired height using three passes to achieve a 3mm thickness.

• Embed the Reinforcement Fleece into the compound.

• Apply a second coat using the spreader to ensure complete coverage of the fleece (3mm thickness). Ensure proper adhesion and smooth out any air pockets.

• Tuck the fleece at corners and creases to eliminate voids.

• Torch the protection cap sheet onto the compound using the traditional method.

Horizontal Surface

First Coat

• Use a rubber-bladed squeegee to apply the compound in a rectangular grid pattern.

• Pour a bucket of compound along the top line of the grid and push 2/3 of the material towards yourself to create a 3mm thickness.

• Repeat the process over the entire grid to achieve the required thickness.

• Use the rectangular grid method for at least three passes with the squeegee for proper thickness control.

Reinforcement Fleece

• While the first layer of compound is hot, embed the fleece into it.

• Unroll the fleece and brush it carefully to avoid air pockets, folds, or wrinkles.

• Overlap the fleece by 75mm at the row connections.

• Reinforce construction joints and cracks with an additional fleece strip.

• Utilise a proprietary joint-sealing system for expansion joints.
  
  

Second Coat

• Apply the second layer of hot compound without delay, ensuring complete coverage of the fleece.

• Use the same rectangular grid method for application as with the first layer.

• Maintain a nominal thickness of 3mm for the second layer, ensuring complete coverage of the fleece.