Building Out Bugs: Weep Holes

Author, Cassie Krejci, Ph. D.

Author, Cassie Krejci, Ph.D.

Hello and welcome to another week of the TERM® Barrier System blog series! This week we will be continuing our summer blog series, Building Out Bugs, by highlighting a way you can block pests from entering the home through weep holes. As part of the TERM Barrier System, Polyguard has developed the TERM Weep and Vent Barrier specifically designed for long-term exclusion.

TERM® Weep & Vent Barrier - Weep Holes

Weep holes are openings on the structure’s exterior left between bricks by the mason. This small opening allows moisture to drain from the structure and for air to circulate. The problem with this necessary opening is that termites and other pests such as scorpions, ants, and small rodents can utilize the weep hole to gain access to the structure.

Termites attempting to exit a home

Termites attempting to exit a home from the weep hole after their mud tube had been removed.

When utilizing screen to exclude termites and other pests, it is important to consider screen size. The following table shows the screen aperture sizes that are required to exclude common pests.

Pest Exclusion Mesh Opening ComparisonAs you can see, screen with openings of 1/55th of an inch or smaller are required to exclude subterranean termites. To develop the TERM Weep and Vent Barrier, we wanted to use a material that blocked the most pests while still allowing the structure to drain and vent. An example of this specifically-sized screen material, called TERM Micromesh®,  is shown below with a subterranean termite.

TERM® Weep & Vent Barrier excludes all sizes of pests

The TERM Weep and Vent Barrier is a non-structural pest barrier which, when properly constructed as part of a masonry wall, will exclude pests of all sizes from passage. Polyguard’s TERM Weep and Vent Barrier incorporates a stainless-steel, corrosion-resistant screen and is unique in its ability to exclude both very small and larger pests. The very small mesh openings have been proven to block even the smallest termites found in North America. The strength of the stainless-steel mesh and the strength of the melt bond between the screen and the frame will resist every pest from the smallest termites to larger pests such as rodents, snakes, and scorpions.

TERM® Weep & Vent Barrier

The TERM Weep and Vent Barrier uses a 3/8” x 1 ½” x 4” rectangular PETG plastic frame, a stainless-steel mesh screen with 0.017” openings which is melt bonded to the plastic frame.

Weep holes are often left unsecured which, of course, offers no protection against foraging pests. Corrugated plastics and steel wool pieces are also used to deter pests. While this may work short term, it is not a permanent solution. Corrugated plastic leaves spaces large enough for small insects, like termites, or determined insects, like roaches, to pass through the weep. Steel wool needs to be recharged, as rodents will pull the material from the weep hole to gain access, or to use the steel wool in nests.

TERM® Weep and Vent Barriers for use on new construction

It’s important to note that the TERM® Weep and Vent Barriers are intended for new construction. TERM Weep and Vent Barriers are a component of the pesticide-free TERM Barrier System which, when properly installed as part of the building envelope, acts as a barrier to almost all pests.  Because almost all pests are excluded for the life of the structure, the need for pesticide treatment should be permanently and drastically reduced.

Completely installed TERM® Weep and Vent Barrier

Completely installed TERM® Weep and Vent Barrier

To inquire about TERM® Weep and Vent Barriers for your next home or building project, or for additional information on the TERM® Barrier System products, please feel free to email me at