Bostik Ultraset® SF Polyurethane Flooring Adhesive

When laying timber, engineered, or bamboo flooring, the right adhesive prevents call-backs for lifting, cupping, or squeaking. Bostik Ultraset SF provides a flexible, high-strength bond that moves with timber, ensuring a durable, quiet floor. This solvent-free adhesive is specifically formulated for lasting performance over concrete subfloors, even those with radiant heating.

Why this product exists

Timber and bamboo flooring installations demand an adhesive that can adapt. Ultraset SF is a single-component polyurethane adhesive engineered to meet these specific challenges. Unlike traditional rigid or solvent-based adhesives, its solvent-free formulation means zero VOCs, protecting installers and occupants alike. Its inherent flexibility accommodates the natural movement of timber without compromising bond integrity, preventing common flooring failures by creating a durable, water-resistant connection that will not re-emulsify from residual moisture. This maintains floor stability and appearance over time.

The numbers that matter

Bostik Ultraset SF is designed for longevity and performance, with specific properties addressing critical flooring challenges. Its 600% elongation ensures the adhesive can absorb the natural expansion and contraction of timber and bamboo, preventing stress-induced cracking or delamination of the bond line. A Shore A hardness of approximately 52 provides a firm yet elastic bond, allowing sufficient movement without sacrificing structural adhesion. Meeting the BS EN 14293 standard for parquet adhesion with a tensile shear strength of 1.4 N/mm² means it delivers a reliable, tested bond strength for demanding flooring applications. As a solvent-free, zero VOC formulation, it contributes to healthier indoor air quality during and after installation, making it suitable for residential and commercial projects alike. This formulation also makes it non-flammable, enhancing site safety.

What it's like to use

Bostik Ultraset SF comes ready to use, requiring no mixing, which streamlines application. It spreads as a smooth paste that holds peaks, allowing for precise trowel application. The adhesive offers a tack-free time of approximately 4 hours and light traffic walk-on in 8-10 hours at 23°C and 50% RH, providing a workable window while still allowing for efficient project progress. For clean-up, uncured adhesive can be removed using mineral spirits, Shellite, or paint thinners, or with Bostik Handy Wipes, taking care with prefinished timber coatings.

Where this product excels

Bostik Ultraset SF excels in direct stick applications for a wide range of timber and bamboo flooring. It is the adhesive of choice for adhering parquet, solid strip softwood, hardwood, engineered, and bamboo flooring directly to concrete subfloors. Its flexible nature makes it particularly effective for installations over radiant heating systems, where thermal cycling demands an elastic bond that won't crack under stress. The adhesive also provides a secure, acoustic-enhancing bond for recommended acoustic underlays, integrating seamlessly into noise reduction systems for multi-story buildings or commercial spaces.

How it fits in a real system

Successful timber flooring installations depend heavily on proper subfloor preparation. Ultraset SF is often the final bonding layer in a comprehensive subfloor system. For new or ground floor concrete slabs, especially where moisture is a concern, the process typically begins with Bostik Ultraseal Vapour Barrier to prevent moisture migration. If the subfloor requires levelling, Bostik UL-200 self-levelling compound is applied, often primed with Bostik PrimeGrip Non-Porous. Ultraset SF then forms the critical flexible bond to this prepared, stable, and dry subfloor, ensuring the long-term performance of the timber flooring.

Choose this when

• Installing timber, engineered, or bamboo flooring: Its specific formulation accommodates the natural characteristics of these materials.
• A flexible, high-strength bond is critical: The adhesive absorbs timber movement, preventing cupping, lifting, and squeaking.
• The subfloor incorporates radiant heating: Its heat tolerance and flexibility maintain bond integrity through thermal cycles.
• Indoor air quality is a priority: The solvent-free, zero VOC formulation ensures a healthier environment.
• Acoustic performance is required: Its properties contribute to noise reduction in flooring systems.

Don't use this when

• Not for: Application over any acrylic primer or sealer, as adhesion will be compromised.
• Not for: Dense, burnished concrete surfaces without prior abrading or sanding to achieve a mechanical key.
• Not for: Direct contact with exposed Bostik PrimeGrip; any exposed primer must be removed or covered with Bostik UL-200.
• Not for: Use as a waterproofing membrane; it does not prevent moisture migration through subfloors.
• Not for: Installation on wet, contaminated, or friable surfaces, which will lead to bond failure.