Can I glue directly to ISO with Acrylic Water Based adhesive?

Posted: 01/28/2019

No, Acrylic Water Base Bonding Adhesive must be installed over a porous substrate in order to cure properly.  Approved substrates are:  High Density Wood Fiber (non-asphalt coated), DensDeck Prime, Securock, Plywood and OSB (rough side up).

Mule-Hide’s Acrylic Water Base Bonding adhesive is a single-side, wet lay-in adhesive approved for use on slopes of 2” per foot or less with EPDM membranes only.  The EPDM membrane must be set into the Acrylic Water Base Bonding Adhesive while it is still wet (immediately upon application of the adhesive).  This allows the installer approximately 20 minutes in which the sheet can be lifted and repositioned if necessary. 

You may be asking yourself, if I have to put the membrane in the glue when it is still wet and I have about 20 minutes to pick it up and move it if I have to, how does it ever adhere permanently?  Excellent question and the answer has everything to do with that porous substrate requirement.  In order for the adhesive to cure properly and adhere the membrane on the roof, the moisture in the wet adhesive must be removed.  The approved substrates draw the moisture out of the adhesive, leaving just the really good “sticky stuff” from the adhesive behind.  Acrylic Water Base Bonding Adhesive is not approved over ISO because the facer on the ISO does not have the porosity needed to draw out the moisture in the adhesive.

Here are some other interesting facts about Acrylic Water Base Bonding Adhesive. 

  • The maximum slope of 2” per foot or less is needed because the membrane must be set in wet adhesive to work.Installing EPDM membrane with Acrylic Water Base Bonding Adhesive on slopes steeper than 2” per foot can result in the membrane sliding down the slope before the adhesive has time to set up.
  • Acrylic Water Base Bonding Adhesive is not approved for vertical surfaces.The contractor must switch to an approved contact adhesive on all vertical surfaces.
  • Because Acrylic Water Base Bonding Adhesive is applied to only one surface, a contractor will get twice the coverage out of a pail over a standard contact adhesive.

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