The three firms are Erdemann Gypsum, Shazaad and Deco Dura Creations, which are certified to make gypsum products such as plasters, medallions, cornices and corners.
Erdemann Gypsum has been granted two licenses; one for its Athi River factory where it manufactures cornices, corners and medallions and the second for its Sh500 million plant in Kitui where it mines gypsum for manufacture of boards and plasters.
The company recently cautioned builders over the health risks posed by imported gypsum products that are said to be made from deadly industrial by-products.
There are concerns that artificial or synthetic gypsum products, which are mostly made from sulphur dioxide gases from coal-fired power plants, are harmful to people.
Erdemann Gypsum boss John Yang says: “We should use natural gypsum building materials from natural gypsum which is safe for our health,” adding that the government should inspect imported products to ensure they do not contain toxic materials.
According to Kebs communications manager Patricia Kimanthi, the bureau uses the American Society for Testing and Materials’ Standards and European Standards Specification to monitor the quality of gypsum products.
“Imports of these products are subjected to the same inspection and testing requirements,” Ms Kimanthi said.
Gypsum boards are checked for dimensions, flexural strength, water resistance, nail-pull resistance and finish, while gypsum binders and plaster are tested for calcium sulphate content, sound proof qualities and fire resistance.