Dust which is considered potentially toxic associated with gypcrete is generated during crushing, mixing, sanding or otherwise working with the product.
Reviewing a manufacturer's Material Safety Data Sheet (MSDS), most concern of health risk is associated with dust created by the raw ingredients. Once these raw materials are combined with water and allowed to cure, gypcrete is considered stable.
To prevent dust accumulation during construction it would be recommended that all drilling and cutting to be done using a wet saw or drill eliminating the production of dust.
- If dust is produced, wipe up with a damp cloth to reduce dust from being released into the air and allow ample fresh air to flush out the area.
- Also I would recommend sealing off any areas where drilling or cutting is being performed to contain dust being produced and aid in the cleanup process.
As for the underlayment, it is typical for the application of either rosin or felt paper to be installed prior to the flooring system. However, most engineered flooring manufacturers will specify a particular type underlayment for their flooring system. In some cases the engineered flooring system must be glued in place. If this is the case, no underlayment will be installed.
Good luck on your endeavors,
Harold J Remlinger, AIA, LEED AP Principal Architect DesignTeam Plus, LLC