1) The "make it look like new" approach
Mistake: Making the historic building look completely smooth, shiny and like a new building.
Why is it wrong? Historic buildings carry the marks of time. The traces left by history are part of the building's identity. Over-restoration destroys original surfaces irreversibly.
Right approach: Preserve the building's historical traces. Intervene only where necessary and with clear justification. Aim for a correct appearance, not a "clean" one.
2) Using cement-based mortar and plaster
Mistake: Using cement-based pointing and plaster on stone or brick walls.
Why is it wrong? The wall cannot breathe. Moisture is trapped inside. Salt efflorescence, blistering and surface loss begin. Damage is directed at the main material.
Right approach: Analyse existing mortar. Use lime-based, breathable mortars. Design joints to be weaker than the main material.
3) Repairing surfaces without addressing the moisture source
Mistake: Hiding wall blistering and spalling with plaster and paint only.
Why is it wrong? The moisture problem continues. The same damage recurs quickly. The building keeps deteriorating from within.
Right approach: Identify the moisture source (roof, ground, services). First ensure water and moisture control. Surface repair comes last.
4) Removing and replacing timber entirely
Mistake: Replacing timber elements that have partial decay with entirely new ones.
Why is it wrong? Original material is lost. The building's historical integrity is damaged. Unnecessary intervention is made.
Right approach: Remove the source of decay. Keep sound parts. Apply local repair and timber splicing (prosthesis) where needed.
5) Completing without restitution evidence
Mistake: Completing missing or collapsed parts by saying "it must have been like this".
Why is it wrong? Historical truth is distorted. An interpretation that does not belong to the building is added. There is no scientific basis.
Right approach: Complete only on the basis of documentation. Clearly distinguish any speculative parts. If there is no evidence, avoid completing.
6) Using aggressive cleaning methods
Mistake: Cleaning with sandblasting, high-pressure water or strong chemicals.
Why is it wrong? Surface texture is worn away. Patina is lost. Irreversible surface loss occurs.
Right approach: Clean with minimum intervention. Choose the method according to surface type. Test on a small area first.
7) Imitating the old with new additions
Mistake: Trying to make new additions look as if they were old.
Why is it wrong? Historical reading becomes difficult. It misleads future generations. It goes against ethical principles.
Right approach: New additions should be simple and compatible. They should be distinguishable on close inspection. They should not overshadow the old.
8) Neglecting site supervision
Mistake: Drawing the project and leaving implementation entirely to the site.
Why is it wrong? Craftsmen's habits override the project. Materials and details change. Mistakes are noticed too late.
Right approach: Carry out continuous and disciplined site supervision. Document unexpected situations. Revise the project on a scientific basis when needed.
9) The "finish quickly" pressure
Mistake: Skipping or compressing stages to save time.
Why is it wrong? Samples and tests are not done. Mistakes appear during implementation. Greater cost arises in the long run.
Right approach: Accept that restoration takes time. Put quality before speed. Plan the schedule realistically.
10) Conclusion: Mistakes often come from method, not intention
Restoration in historic buildings: is not a show of strength. Not a race to modernise. Not about speed and show.
Right restoration: is quiet, unassuming, and puts the building itself first.