New Product Review - DuraGuard

by Ronald Harriman

In light of the current availability and price issues with isocyanurate, the most common roof insulation board, it seems likely that more roof systems will be specified and installed in 2005 using alternatives such as polystyrene, lightweight insulating concrete, gypsum boards, fiberglass, wood fiber, perlite, or a combination of materials.

DensDeck has grown in use the last several years, commonly used as a coverboard over other insulation products or as a single layer material.  To add versatility to its usefulness, Georgia-Pacific introduced a new product, DuraGuard in February 2004.  DuraGuard, similar to DensDeck, is a gypsum roof board utilizing fiberglass mats over a gypsum core.  What makes DuraGuard unique is the addition of a blue low-perm coating to the board's top surface.  The board comes in 1/4", 1/2", and 5/8" thicknesses, 4' widths, and either 4' or 8' lengths.

This coating reduces the need for field primers, makes adhesive application easier and more uniform, and most notably, provides improved adhesion characteristics.  This improved adhesion lends itself well to a variety of roof system applications such as hot applied built-up roofs, hot applied modified bitumen membranes, and self-adhered membranes.  One other benefit DuraGuard has is that the low-perm coating isolates the gypsum from hot asphalt and minimizes the affects of calcination bubbles.   

Although it is a more sensitive application, DuraGuard can also be used with fully adhered single-ply membranes (solvent based adhesive), torch applied modified bitumen, and spray foam.  It is not recommended for use with mechanically attached single-ply membranes, fully adhered single-plies (water based adhesives), and cold applied modified bitumen.

Because of VOC (Volatile Organic Compound) issues and ease of application, Benchmark anticipates a marketplace increase in self-adhered membranes in the coming years.  The biggest obstacle or concern with self-adhered membranes is the initial and long-term adhesion of the membrane to the substrate.  Improvements to this adhesion are very appealing and DuraGuard could prove to be a practical solution.  Since self-adhered technology and DuraGuard are both relatively new, we will closely monitor adhesion on projects and various field trials.

Project types that appear to be most conducive to DuraGuard include projects with:

·        Integral vapor retarders and temporary roofs

·        High humidity situations / situations where mold growth is a concern

·        Self-adhered membranes

·        Bottom layer and/or coverboard with extruded polystyrene insulation, to achieve fire ratings and adhesion substrate

·        The need for soundproofing enhancements

·        High traffic roofs

·        Hot applied systems with low R value requirements

There is no roof membrane or insulation product that is appropriate for all circumstances  - DuraGuard is no different.  Proper roof design will consider the specific project requirements and make product selections that best accommodate all conditions.  While time is generally the best measure of a material's success, we feel it is important to carefully consider new products, and to specify them only if they best meet the project criteria.