Clearances in excess of those allowed by NFPA 80 are one of the most common problems with fire door assemblies, and can be very difficult to resolve. National Guard Products has just released two new UL Certified accessories for excessive fire door clearances, which will help to bring many of these doors into compliance. The catalog pages can be downloaded here and list prices are available on the NGP product pages (click images on the right).
NGP-Edge Intumescent Fire Seal (9200) can be used at the head and jambs when clearance measures between 1/8 inch and 5/16 inch. The self-adhesive seal is listed for use on 20-minute rated UL10B and UL10C wood or hollow metal fire doors (including the hose stream test required for 20-minute doors in Canada). The product can be mounted on the door edge or on the frame rabbet depending on aesthetic preference. An NGP strike shim is also required for proper latchbolt engagement.
NGP-Edge Intumescent Door Shoes (9250) can be used to address excessive clearance measuring up to 1 1/2 inch at the bottom of the door. It is listed for use on 20 minute rated UL10B and UL10C wood or hollow metal fire
doors, and restricts the passage of smoke with a variety of gasketing combinations including nylon brush, neoprene, vinyl, and thermoplastic.
Roger Skold is the Technical Director at NGP, and he answered my questions about these products. Here is a summary:
Is the edge seal material applied only where there are oversized clearances? Yes, the material is only installed where the oversized clearance exists. For example, if the problem is only at the head, the intumescent seal is installed at the head where the clearance is excessive, and the jambs are left as-is.
What happens at hardware locations – ie. a mortise lock? Does the installer mount the intumescent above and below the lock? Yes, it was tested as follows: jamb mounted – above & below a 4-7/8” lock strike, door mounted – above and below an 8” mortise lock face. Excessive clearance is less likely at the hinge edge, but the product can be used on the hinge jamb if necessary, and can be stopped above/below each hinge.
Is there any information available about the lifespan of the adhesive? It is a tackified acrylic and basically once bonded is considered permanent. The “shelf life” prior to installation is more important and is recommended as 1 year (will slowly degrade after that).
Can the intumescent edge seal be used at the meeting stiles of pairs? The product was tested on single doors, so use at the meeting stiles would be subject to acceptance by the Authority Having Jurisdiction (AHJ).
If you have additional questions, leave them in the comment box and I will discuss them with Roger and update the post.