BLOG / NEWS RELEASE

Why Standard Prep Methods Don’t Work on Brick Manholes

When it comes to rehabilitating brick masonry manholes, preparation is everything. Too often, crews apply concrete surface preparation standards to brick structures — but what works for concrete can actually damage brick materials.

Brick manholes require a different approach: gentler, tailored methods that respect the material’s unique properties. Without it, bonded rehabilitation systems are at risk before they’re even installed.

Why Brick Isn’t Concrete

Brick masonry manholes, typically built from clay or shale brick bonded with portland-cement mortar, are some of the oldest underground assets still in use. While fired ceramic brick resists corrosion, the surrounding mortar deteriorates over time, especially from biogenic sulfide attack.

That means preparation needs to target weakened mortar while preserving the integrity of the brick.

The process begins with thorough cleaning to remove fats, oils, grease (FOG), dirt, coatings, and loose material. Standard practice calls for:

  • High-pressure water cleaning: at least 5,000 psi with a rotating spray or fan nozzle, kept 6–12 inches from the surface at a 45°–90° angle.
  • Biodegradable cleaning agents or heated water (up to 210°F / 99°C) for heavily contaminated surfaces.
  • High-pressure slurry blasting: at least 4,000 psi with sand injection, where needed.

Once clean, the structure needs to be repaired before applying linings:

  • Replace missing bricks and repoint mortar joints.
  • Stop active water infiltration with hydraulic cements or polyurethane injection grouts.
  • Remove existing manhole steps that could interfere with lining installation.

A sound surface is just as important as a clean one. Crews should:

  • Perform a soundness test: run a flathead screwdriver at a 30° angle. If only a shiny mark remains, the surface is sound. If material loosens, more prep is needed.
  • Confirm pH: surfaces must test at least pH 9 before Epoxytec products are applied.

If the manhole is re-exposed to sewer service after prep, it should be re-cleaned before lining begins. Think of this as the final sweep before installation.

Manhole preparation isn’t just technical — it’s also about safety. Crews should always:

  • Wear eye/face, respiratory, and hearing protection
  • Use gloves, protective footwear, Tyvek-type coveralls, and a hard hat
  • Ensure proper ventilation
  • Inspect all tools and PPE before use
  • Conduct a written risk assessment for each task, including confined space entry

Bottom Line

Brick manholes aren’t concrete manholes — and treating them as such can create costly mistakes. By following a preparation process designed specifically for brick, contractors ensure bonded linings perform as intended, protecting critical infrastructure for decades to come.

This blog content is adapted from a NASSCO, Inc. Tech Tip authored by Epoxytec’s Vaughn O’Dea on brick surface preparation for masonry manholes. Vaughn also contributed to NASSCO’s revised Manhole Rehabilitation Performance Specification Guideline (PSG), helping author the section on brick surface preparation.