Module 2 · Buildings and How They Handle Moisture
2.6 System-Built and Non-Traditional Housing
8 min read
Britain built well over a million non-traditional homes in the post-war decades, across dozens of named systems. Their moisture behaviour is not a variation on masonry — carbonation in precast concrete, interstitial condensation in no-fines, cold bridging and corrosion in steel frame are type-specific mechanisms with type-specific evidence. For these buildings, identifying the system is not context for the survey; it is the first diagnostic step, and getting it wrong invalidates everything after.
Learning objectives
By the end of this lesson you will be able to:
- Recognise the major non-traditional families from visible evidence.
- State the characteristic moisture and durability mechanism of each family.
- Explain why designation as defective under the Housing Defects legislation matters to a survey.
- Know when to stop and recommend a specialist structural appraisal.
Key terms
- No-fines concrete
- Concrete cast without fine aggregate, giving an open-pored monolithic wall. Drains rather than absorbs, and depends completely on its render for weathering.
- PRC (precast reinforced concrete)
- Panel and post systems assembled from factory-cast units. Many named types were designated defective under the Housing Defects Act 1984.
- Carbonation
- Atmospheric CO2 reacting with concrete over decades, reducing its alkalinity so embedded steel is no longer passivated and begins to corrode.
- Designated defective
- A statutory designation of specific system types as inherently defective, with consequences for mortgageability and for the assistance available to owners.
Read the rest of Buildings and How They Handle Moisture
Module 1 is open to everyone. The remaining six modules — building science, each damp mechanism in depth, meters and thermal imaging, the full inspection method, and report writing — are free too. We just ask for an email so you can pick up where you left off, and so we can send your certificate when you finish.