Balco Expansion Joint Covers: Types and Applications

There are two primary configurations. Type A is a flat cap for joints between masonry units on the same plane, like on copings. Type B is a 90-degree cove cap used for right-angle joints, such as where a window sill meets a wall or at corner junctions.

It's ideal for historic restoration and new construction. Common applications include protecting joints on parapets, copings, cornices, belt courses, window and door frames, entrance steps, and other projecting masonry elements vulnerable to weather.

The system is made of soft lead, which has a low elastic modulus. This allows it to remain flexible and 'creep' into new configurations as the building settles or moves. Unlike rigid materials, it absorbs stress without tearing or shearing, maintaining a continuous seal.

Yes, it can be painted to match the surrounding masonry. If left unpainted, the lead surface quickly oxidizes to a neutral grey color that naturally blends in with most stone and masonry, making it visually unobtrusive for restoration projects.

We offer stock sizes in both Type A (flat) and Type B (cove) profiles to fit joint sizes from under 3/8 inch up to 1 1/2 inches. For non-standard conditions, custom and larger sizes can be manufactured upon request to meet specific project requirements.

Its ability to protect vulnerable, original masonry from moisture damage without altering the building's aesthetic makes it ideal for preservation. It is specified in U.S. General Services Administration (GSA) technical procedures and has a proven track record on numerous national landmarks.