20/08/2026
BRAND NEW Historic England Guidance: Assessing Damp in
Historic Buildings, A Practical Guide to Investigation and Diagnosis? 🏛️🔍
Misdiagnosing damp in traditional or historic structures is a common pitfall in relation to the Building Pathology RICS APC competency.
Before you advise a client to inject a chemical damp-proof course (DPC) or apply an impervious tanking membrane, pause and consult Historic England’s brand new guidance; HEAG311 – Assessing Damp in Historic Buildings. This should be read alongside the RICS Joint Position Statement.
Here are three key takeaways, which you could incorporate into your RICS APC final submission:
1️⃣ Breathability is everything
Traditional buildings rely on moisture movement through permeable materials (lime mortar, timber and brick). Applying modern, non-breathable sealants traps moisture, accelerating decay rather than preventing it.
2️⃣ Diagnosis before action
Don't rely solely on electrical resistance meters (which often measure salts, not pure moisture). Use non-destructive, holistic diagnostic methods, such as checking rainwater goods, subfloor ventilation and ground levels, before advising clients on intrusive remedies.
3️⃣ Minimal intervention
Under conservation principles, the best repair is usually the least intrusive. Address the underlying cause (e.g., clearing a blocked gulley) rather than forcing modern 'quick fixes' onto the fabric of historic buildings.
💡 RICS APC tip - if you have an example of diagnosing damp in a historic building in your final submission, explain how you investigated the source of moisture and why a sympathetic, non-destructive approach was recommended over harsh chemical treatments.
📖 Read more: https://buff.ly/Olrc4zr
