INTERIOR FINISHES

This chapter addresses the methods of attaching an approved 15 minute thermal barrier over SmartBlock insulating forms as required by Chapter 26 of the 1997 UBC.

4.1 Gypsum Wall Board

All habitable areas of structures built with a SmartBlock insulating forms are required to be separated from the EPS by a thermal barrier having an index of 15. (See UBC Chapter 26.) The most common method is the use of gypsum wall board (GWB), also referred to as drywall. A minimum thickness of 1/2" is required to meet this condition. The 1997 UBC Chapter 25, which outlines the conventional methods of attaching drywall, requires that screws or nails be attached, as a minimum, 18" on center whether the drywall is attached horizontally or vertically.

4.1.1 Metal Clips

At present, the UBC does not specifically address attaching drywall to SmartBlock insulating forms. The UBC does state, however, that a test can be used as an alternative to the standard methods of attachment for thermal barriers.  SmartBlock insulating forms were tested using metal clips that provide mechanical attachment with the concrete and a fastening surface for drywall screws.

Prior to the pour, in order to achieve mechanical attachment with the concrete, a minimum of four 20-gauge galvanized, 2" wide clips (sold under the product name SmartTach™) are imbedded, through SmartBlock, into the concrete.  The drywall is attached to the SmartTach with 3/4" minimum self tapping drywall screws 12 inches on center.  It is strongly recommended that drywall adhesive compatible with EPS be used to attach the remaining portion of the drywall to the SmartBlock insulating forms or additional screws at reasonable spacing.   Finishing of the drywall, such as drywall tape and topping mud, should be done in accordance with conventional practice.  

4.1.2 Other Attachment Methods

Attaching drywall to the top wood plate instead of the metal clips described above should be sufficient to achieve the required thermal barrier. In order to achieve the required 15 minute thermal barrier over SmartBlock insulating forms as stipulated in Section 1713 of the 1991 UBC, you need only attach the drywall to the top strip. No other attachment is required although use of a drywall adhesive to assure a smooth and problem free surface is strongly recommended.

 

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