Cement board: innovative exterior applications

Several manufacturers sell a polymer modified adhesive and require that to be used for warranted work. Check out this website and this website.

For standard PermaBASE® Cement Board the surface burning characteristics are Class A and the ASTM E84 results are 0 Flame Spread and 0 Smoke Development. For the PermaBASE CI™ Insulated Cement Board the ASTM E84 results are Flame Spread less than 25 and Smoke Development less than 450. Refer to the UL Evaluation Reports for both products including the NFPA 285 testing with the PermaBASE CI Insulated Cement Board. UL Evaluation Report PermaBASE Cement Board, UL Evaluation Report PermaBASE CI Insulated Cement Board.

The ASTM “Standard Practice for Application of Direct-Applied Exterior Finish Systems” for cement board direct applied stucco is ASTM C1516. The ASTM “Standard Practice for Installation Methods for Cement-based Adhered Masonry Veneer” is ASTM C1780.

PermaBASE Cement Board and PermaBASE CI are available in different thicknesses. 1/2” PermaBASE is 2.9 lbs. / sq. ft., 5/8" PermaBASE is 3.65 lbs. / sq. ft. 1" PermaBASE CI is 2.2 lbs. / sq. ft., 2" PermaBASE CI is 2.4 lbs. / sq. ft. and 3" PermaBASE CI is 2.6 lbs. /sq. ft.

The weather resistant barrier is typically applied over the exterior sheathing, but it can be applied over the cement board if the system is designed that way. If a weather resistant barrier is installed in both places, the outer layer over the cement board is for bulk water management and extra insurance against water penetration. Check the appropriate weather barrier placement with the systems manufacturer for warranty requirements.

1/2” PermaBASE Cement Board is appropriate for both interior and exterior applications. Studs must be a maximum of 16” o.c. for tile applications over cement board or gypsum board tile backer substrates.

The EIFS manufacturers have details on their websites for both expansion and control joints.

Cement boards are considered non-structural and are to be considered substrates for finish application. Magnesium oxide boards are not approved for the same applications as cement boards like PermaBASE Cement Board.

The Cement Board Stucco Systems (CBSS) with continuous will give you increased durability, multiple finish options, faster installation, and increased impact resistance over EIFS. From the impact resistance perspective only, think of the golf course setting and stray golf balls hitting the walls of a house or building.

Yes, PermaBASE CI can be installed over CMU and concrete walls. To learn more, click here.

Thin stone and thin brick can be adhered to cement board as a masonry veneer in a soffit application, but the mortar and finish must be less than 10 lbs. / sq. ft.

PermaBASE and our cement board stucco systems are developed to be a lighter weight and more durable alternative/replacement to traditional stucco. You can use PermaBASE as a sheathing behind traditional stucco, but you will still need to apply a metal lath to support the stucco application.

Typical 5/8” gypsum sheathing is 2.5 lbs. / sq. ft., whereas 1/2” PermaBASE Cement Board is 2.9 lbs. / sq. ft., so it is slightly heavier. There really are no problems with installation compared to gypsum sheathing. In most instances, PermaBASE Cement Board is approved as a sheathing substrate.