When preparing commercial office space at the Minneapolis Grain Exchange, contractor, Sonus Interior, was faced with old wood floors with heavy amounts of carpet glue. Schönox SHP, AST, & AP were used to prime, patch and repair, and apply a final subfloor suitable for any flooring product.

Now a thriving office and commercial center, the Minneapolis Grain Exchange was built in 1902. Listed on the National Register of Historic Places, tenants appreciate the blending of the historic structure with modern amenities. Renovations within the building are common necessitating special subfloor products to address the challenges that come with a building occupied for over 100 years.

Preparing the Existing Substrate


The subfloor was uneven throughout the space. The plywood was loose in spots and separating in others and the existing wooden subfloor had heavy amounts of carpet glue.


Loose pieces are nailed down or removed to ready the subfloor for Schönox SHP, special acrylic primer, and AP, synthetic gypsum self-leveling compound. Foam tape is used to protect the walls from the leveling compound providing a dam around the space.

Priming Using Schönox SHP


Schönox SHP, special acrylic primer, is applied over the top of the old carpet glue and plywood. SHP works best on non-porous substrates such as old glue, ceramic tiles, old vinyl, and rubber coverings. SHP greatly improves the bond between the plywood, glue, and Schönox AP, synthetic gypsum self- leveling compound, drying quickly in 1-2 hours.

Patch and Repair Using Schönox AST


Schönox AST, synthetic gypsum rapid drying, smoothing, and patching compound, provides a smooth finish on various substrates. AST can be installed as a true featheredge over a variety of critical substrates.

Schönox AP Pour


Schönox AP, synthetic gypsum self-leveling compound, is mixed with only 6.0 liters of water. A special dust reducing quality releases minimal material into the air. Schönox AP is an excellent self-leveler that is easy to spread and apply. AP is made from a recycled by-product taken from power plant emissions. AP contributes to LEED credits and can go over many existing substrates eliminating debris from growing landfills.


When dry, Schönox AP is free of cracks and has no shrinkage making it ideal for renovations and critical subfloors. The product dries extremely smooth, ready to receive any type of floor covering. Schönox AP can be walked on in approx. 2 hrs. and covered in approx. 24 hours. AP is extremely strong curing to 5800 psi.