Apex Multi-Family
Helping Deliver Affordable Housing Faster
Apex Multi-Family is a UL approved limestone-based Cementitious underlayment designed for use on both new and existing subfloors, providing a durable, high-strength surface ideal for various flooring systems.
Engineered for multi-family construction, Apex Multi supports affordable housing developments to apartment complexes, with high-quality flooring substrate designed to meet the demands of modern residential building projects.
Designed to support fast-paced construction schedules, Apex delivers excellent flowability, rapid drying times, and efficient installation, while offering the versatility to accommodate a wide range of floor finishes.
As the construction industry continues to evolve, many contractors and developers are moving away from traditional gypsum-based underlayments in favour of cementitious solutions that offer enhanced strength, improved moisture resistance, and long-term performance. Apex Multi provides a durable, reliable foundation that helps support quality flooring installations across both wood-frame and concrete multifamily developments.
Why Choose Apex for Multifamily Construction?
- No surface laitance
- High compressive strength for long-lasting floor performance
- Fast drying times to support accelerated construction schedules and reduce downtime
- Excellent durability in high-occupancy residential environments
- Suitable for wet and high-moisture environments
- Enhanced sound attenuation for improved resident comfort
- Suitable for a wide variety of floor coverings
- Suitable for fire-rated floor assemblies
- Reliable performance in both new construction and renovation projects
- Ideal for wood-frame and concrete multifamily developments
- Easy installation
With a high strength formula, it achieves a compressive strength range of 2750 – 3600 psi (19 – 25 MPa) and is highly resistant to surface abrasion, making it suitable for areas with high foot traffic.
The underlayment’s crack-resistance ensures a stable base for all types of floor coverings, including tile, carpet, vinyl, and hardwood.
Apex Multi-Family Products
- Apex Multi 35
- Apex Sound
• Enhanced sound attenuation for improved resident comfort
• Compatible with a wide range of substrates, including concrete slabs, pre-stressed concrete, concrete planks, concrete repair or leveling surfaces, OSB, plywood, and radiant heat systems.
• Suitable for installation over sound attenuation systems designed for flooring applications.
• Can be applied in UL fire-rated assemblies.
• Compatible with a variety of floor coverings, such as vinyl, carpet, hardwood, and floor tiles.
- High compressive strength and impact resistance
- Suitable for use in wet areas and high-moisture environments
- Apex System provides improved sound attenuation properties
- Ideal for multi-family projects
- Recommended installation thickness of 3/8” to 3” in a single pour
- Apex Multi supports affordable housing developments and apartment complexes
- No surface laitance
Installation
Apex Multi Floor Underlayment is mixed with approved sand and potable water at the job site to yield a lightweight underlayment that weighs approximately 7.5 lbs./sq. ft. at 3/4 in. (19 mm) thickness and has an approximate dry density of 120 lbs./cu. ft. Apex Multi must only be installed by a trained and licensed Apex Multi applicator.
The structural subfloor should be adequate to withstand designed loads with a minimum deflection criterion of L/360.
During the entire installation process, ensure the building is fully enclosed, with the temperature maintained at a minimum of 50 °F (10 °C) for optimal curing conditions. Adequate ventilation is essential to ensure even drying of the applied underlayment, which typically occurs within 5–7 days when applied at a 3/4 in. (19 mm) thickness.
Protect the underlayment from excessive trade traffic (e.g., equipment, heavy tools, carts) by placing plywood or other protective materials over it. Exposure to heavy weight during the curing process can delay drying in those areas, so ensure these sections are thoroughly dry before installing flooring materials.
Concrete Subfloor Preparation
Mechanically prepare the substrate to remove surface contamination and laitance including any concrete sealers or curing compounds and provide an open textured surface. Substrate must be dry, clean and free from loose materials, dirt, oil, grease and all forms of contamination.
Use a suitable bonding agent to ensure solid bonding of the underlayment to the substrate. If the substrate is >85%RH, then a Moisture Mitigation Product will be required.
* If the substrate is <85%RH, then an acrylic primer will be required.
*Always comply with the Moisture Mitigation manufacturer’s guidelines. Respect existing expansion and control joints, and ensure they are properly accommodated during installation.
Wood Subfloor Preparation
Wood subfloors must be structurally sound, clean, and free of dust and contaminants. Wood subfloors must be primed with an acrylic primer prior to Apex Multi underlayment application.
Note: This underlayment is not a structural material and will not resist building movement. Any structural movement in the building can cause stress that may result in cracking of the underlayment.
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