Building Defect Analysis: Structural damage to stone columns in a bay window of a Victorian house

Building Defect Analysis: Structural damage to stone columns in a bay window of a Victorian house

Thursday 25th July 2019

We were recently asked by a client to visit a Victorian mid-terraced house in Highgate, London (N6) suffering from structural issues.

The client was concerned about vertical cracks running virtually the full height of two stone columns either side of a front bay window. Despite her previously filling these cracks, they soon reappeared.

In particular, the client wanted to know whether this cracking could form the basis of an insurance claim, and requested a diagnostic assessment to be carried out detailing the necessary remedial works.

Insurance Claim

As the cracking was a result of wear and tear, not through subsidence, or to do with circumstances outside the control of the Client such as accidental damage, these repair works will not be covered by an insurance claim and will be dismissed by the assessor.

Diagnosis of Damage

The diagnosis of the problem has been identified as a rusting central steel rod. Mild steel rods can rust and expand to multiple times the original material mass and when this happens this causes spalling on the concrete. Initially cracks longitude will appear vertically to the column and as more water comes into contact with the steel rod, the expanding cracks eventually cause spalling chunks of stone to fall off, exposing the steel core rod.

Remedial Works

Unfortunately, there is no quick fix solution for solving rusting steel within stone columns.

The only remedy in most cases is to replace the columns with either reconstituted stone or concrete reinforcement using stainless steel rods.

Lots of these columns were replaced with concrete as a result of bomb damage during the Second World War and therefore it is a very common problem throughout London with Victorian properties of this type.


This article was written by Carl O'Boyle BSc MRICS FCIOB MFPWS. Carl is a full professional member of the Royal Institution of Chartered Surveyors, a member of the Faculty of Party Wall Surveyors and a Fellow of the Chartered Institute of Building for which he currently sits on the CIOB professional conduct committee and adjudications panel.

If you have a building defect in Highgate, London or the surrounding areas then please call us at our office on 0208 426 1448.