Pliolite: A cautionary tale
Explore the science behind Pliolite resin, its origins as a damp-proofing agent, and why its use in period and listed buildings can lead to significant and irreversible damage. Understand why this material should be avoided in conservation and restoration projects.
Understanding Pliolite: Its origins and properties
Pliolite resin was developed as a synthetic rubber-based coating, primarily intended for damp proofing and exterior protection in modern construction. Its unique chemical structure provided excellent water repellency, excellent adhesion, and it's marketing states that it's shower proof in a short space of time, making it seem like a promising solution to DIYer's and Armchair Experts,for various moisture-related issues. Scientifically, Pliolite is a styrene-butadiene copolymer, known for its elasticity and resistance to alkalis and acids. This composition allowed it to form a tough, impermeable film, which in modern contexts, could be beneficial, but note: that's in modern contexts, it's completely wrong for traditional buildings where moisture movement is paramount.
Why Pliolite should never be used on old buildings
Despite its perceived benefits, Pliolite should never be used on period and listed buildings. Historic structures, particularly those built with traditional materials like lime mortars and renders, rely on the ability to manage moisture through evaporation and absorption. Pliolite creates an impermeable barrier that traps moisture within the wall structure.
This leads to several severe problems, including increased interstitial condensation, frost damage, and the deterioration of original building fabric such as timber and masonry.
The trapped moisture can also activate soluble salts within the masonry, leading to efflorescence and sub-efflorescence, causing the rapid decay of stone and brick. This process is fundamentally incompatible with the moisture vapour management required with traditional building construction.
So forget about the rain, remember that moisture created indoors, needs to escape through the walls so it can naturally evaporate into the outdoor atmosphere.
Who benefits from Pliolite? (Nobody)
When it comes to the conservation or restoration of period and listed buildings, nobody benefits from using Pliolite. Its application can cause irreversible damage, leading to costly repairs and the loss of historic fabric.
For property owners, it means unnecessary expenditure and potential devaluation of their heritage assets.
For conservation professionals, it represents a breach of best practice and ethical guidelines, along with you showing that you need an Armchair!
Down in Heritage Lane, we strongly advise against its use in any traditional building context.