About Sika Sarnafil G 410-15 EL Felt

Sika Sarnafil G 410-15 EL Felt sits in the premium end of single-ply roofing. It is a plasticised PVC membrane built up in multiple layers around a glass-fibre inlay that keeps the sheet dimensionally stable, with a polyester fleece welded to the underside. That felt face is the defining feature: it lets the membrane sit directly over tired bituminous roofs and bond into Sarnacol adhesive without the old surface fighting the new one. The lacquered matt top surface carries UV stabilisers and flame retardants, so the sheet holds its colour and its properties through years of direct sun. At 1.5 mm nominal thickness and roughly 2.2 kg/m2, it is light enough to handle on site yet substantial enough to take foot traffic during maintenance.

For Indian roofs, the appeal is practical. Flat concrete decks across the country crack, pond and leak at movement joints, and torch-applied bitumen ages hard and brittle under our sun. A hot-air-welded PVC membrane answers both problems: the welds are as strong as the sheet itself, there is no open flame during lap welding, and the felt back means a leaking bitumen roof can often be overlaid rather than stripped. Because installation is restricted to Sika-trained applicators, the finished system carries the accountability that consultants and facility owners look for on high-value roofs. Space Arc supplies the membrane, the compatible Sarnacol adhesives and the detailing accessories as one coordinated package across Delhi NCR and Pan-India.

The technical insight

The performance comes from how the layers work together rather than from any single property. The glass-fibre inlay resists shrinkage and thermal movement, holding dimensional change to roughly 0.2 percent so the sheet does not creep or wrinkle after bonding. Around that core, the flexible PVC compound stays weldable: when two overlaps are heated to their fusion point, the polymer chains on both faces flow and re-knit, producing a joint that behaves as one continuous material rather than a glued seam. Independent tests put joint peel resistance at 300 N/50 mm and joint shear at 600 N/50 mm, close to the sheet’s own tensile strength of 700 N/50 mm each way, which is why a properly welded Sarnafil roof rarely fails at the laps. The polyester felt underside does two jobs at once, giving the adhesive a mechanical key and cushioning the membrane against sharp aggregate on old bitumen or gravel decks. A high water-vapour resistance factor of 15,000 keeps the roof build-up controlled, while UV stabilisers let the membrane pass more than 5,000 hours of accelerated weathering at grade 0.

Where it is used

• Waterproofing exposed flat and low-slope commercial and industrial roofs
• Refurbishment overlays directly onto ageing bitumen or felt roofs using the compatible felt backing
• Warehouse, logistics and factory roof decks requiring a long-service single-ply system
• Podium, terrace and tower-block roofs on high-rise residential and mixed-use developments
• Roofs where an open flame is undesirable, using cold-adhesive bonding plus hot-air welding
• Large-span roofs needing fast, weldable sheet installation with reliable seam integrity
• Cool-roof strategies using the traffic-white colour for high solar reflectance
• Detailing at upstands, parapets and penetrations as part of the wider Sarnafil G 410 system

Key advantages

• Hot-air-welded laps create homogeneous seams as strong as the sheet, with joint peel of 300 N/50 mm
• Polyester felt backing bonds cleanly over old bitumen, often avoiding a full strip-and-recover
• Glass-fibre inlay gives high dimensional stability, limiting movement to about 0.2 percent
• UV stabilisers and lacquered surface deliver proven, colour-stable performance over decades
• Flame retardants built into the compound, with Reaction to Fire Class E to EN 13501-1
• CE marked and declared to EN 13956 for polymeric roof waterproofing sheets
• Traffic-white option offers a high Solar Reflectance Index for cool-roof and LEED credits
• No open flame during lap welding, improving site safety over torch-applied systems

Limitations & considerations

• Installation is restricted to Sika-trained and approved applicators, not general labour
• Not compatible in direct contact with EPS, XPS or PF insulation, or with tar, bitumen oils and solvents
• Must not be laid on wet, damp or unclean substrates; the deck has to be sound and dry
• Adhesives and cleaners are generally limited to use above +5 C ambient, constraining cold-weather work
• Hot-air welding needs trained operators and calibrated equipment to guarantee seam quality
• External fire classification BROOF(t4) was shown as pending on the data sheet, so project-specific confirmation is advised

Selection & best practice

Specifications

Industry use cases

How we position Sika Sarnafil G 410-15 EL Felt

Sarnafil G 410-15 EL Felt is the felt-backed member of the wider Sarnafil G 410 family; where the deck does not need felt cushioning, the plain-backed G 410 membranes and the loose-laid, mechanically fixed S 327 range cover the same duty, all installed with Sika Sarnacol adhesives and Sarnafil detailing accessories that Space Arc supplies together. For roofs that call for a liquid-applied rather than sheet solution, Sika’s Sikalastic membranes are the natural cross-reference. Space Arc does not position any Fosroc product as a genuine equivalent here, because Fosroc’s waterproofing line is cementitious and liquid-applied (Brushbond, Nitoproof, Proofex) rather than heat-welded single-ply PVC; those are complementary for basements, wet areas and below-grade tanking, not a like-for-like swap for an exposed PVC roof membrane.

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