with expert Severin Werner of LPM AG
Summary
In this episode of Concretely, Johannes Lohner talks to Severin Werner, an experienced chemist and expert surveyor at LPM, about coatings in the construction industry. The focus is on common weaknesses during application, causes of structural damage, moisture measurement methods, and how quality assurance can be improved.
Coatings in Construction: More Than Just Aesthetic
Coatings have become an essential part of modern construction—whether in parking garages, hotel kitchens, or industrial halls. But they don’t just serve aesthetic purposes; they are critical for protecting concrete structures. Especially in areas exposed to chlorides or moisture, coatings can extend the service life of concrete by up to 20 years. At the same time, expectations are rising: clients often assess only the appearance—even if the technical requirements are clearly defined in the specifications.
Most Common Causes of Damage
A key topic in the conversation is the susceptibility of coatings to damage. According to Severin Werner, who has assessed over 1,000 damage cases, time pressure is one of the main causes. If coatings are applied too early—on damp substrates, for example—or without accounting for temperature and dew point, serious follow-up damage can occur. Processing errors such as incorrect mixing ratios in 2-component systems or even the use of unsuitable products are also common. Mistakes often begin with the tender: products are sometimes specified that don’t even exist in the form described.
Osmosis Damage: The Invisible Threat
One striking example is a clarifier tank whose coating developed severe blistering over time. The cause was a combination of harmful salts in the concrete and osmosis effects: water diffused through the coating, reacted with salts in the substrate, and destroyed the concrete structure—eventually allowing it to be scraped off by hand. Osmosis isn’t a rare case: rear-side moisture, residual solvents, and inadequate substrate preparation also cause damage that often doesn’t become visible until months or years later.
The Importance of Accurate Moisture Measurement
A particularly critical topic is the measurement of moisture before application. In practice, electronic devices like Tramex are often used, which only provide relative readings near the surface—often skewed by rebar or aggregate. However, standards require absolute measurement methods like the CM method or Darr method, which determine moisture via mass loss or gas production. If this step is neglected, primers can soften, coatings can fail, or floor coverings can detach—as illustrated by cases in a school and a fitness center.
Coatings Require Proper Quality Assurance
Severin Werner makes a strong case for independent quality assurance: not by the contractor, but by the client or an external inspector. Especially important are surface tensile strength tests, documentation of application conditions, and coordination between trades. Because those who focus solely on time and cost often cut corners where it matters most. Following the “Ruskin’s Law”, this can become expensive—leading to total failure, downtime, and legal disputes. Quality and realistic timelines are the key to durable and reliable structures.