London Underground - reconstruction of South Kensington station faience facade, 2013/14 : new faience block being back-filled
One of the many fascinating projects I was involved in, as London Underground's Design & Heritage Manager, was conservation and restoration of many of the historic structures that the Tube owns and still operates. Out of over 275 stations over 80 are statutorially Listed, including this one, many more are Locally Listed and nearly all have some Heritage Features as assessed by London Underground itself.
Many stations still have faience facades of a type of construction that the Central London Railway (1900) and the Underground Electric Railways of London (1905/6 and later) utilised. The Metropolitan Railway also used faience on many of its early 20th Century reconstructions.
The basic construction methodology is sound - the use of load bearing steel framework and a cloak of effectively mass produced faience blocks - in this case made in Leeds by the Burmantofts Works of the Leeds Fireclay Company. However, some defects can occur if the facade is not waterproof, when moisture meets the steelwork, corrodes and spalls, or if the fireskin of the faience blocks themselves is damaged (such as through hole drilling or physocal damage). The latter tends to invite frost freeze and thaw, further destroying the material.
At South Kensington the issues were compounded by the removal, several decades earlier, of any internal wall finishes when the ticket hall and lift landings. along with the lify shaft, were stripped out for use as a passive ventilation shaft. Some earlier spot repairs, using 'plastic' fillers over wire mesh and coloured resin fillers had also started to fail badly - these tend to be prone to UV failure. All in all the structure and facade was a mess - and first we had to gain Listed Building Consent to undertake intrusive surveys and condition surveys to see what was actually going on.
To cut a long story short we realised we needed to physically reconstruct almost 85 - 90% of the facade, such was the deterioration of the sub-strate and the facade. We had undertaken similar work on other stations and so were able to call on expert manufacturers (Darwen Faience & Terracotta) and construction contractors. The manufacturing of new blocks is not simple as you have to allow for shrinkage in firing, colour matching older and now illegal glazes along with firing temperature variations in colour. To ensure a lack of uniformity - as you don't actually want a 'blank' colour the manufacturer has to also consider glaze weight. The setting out has to be precise - no 'cutting' like tiles, and the new blocks were correctly back-filled with inert packing and tied structurally back to new substrate. All in all - a helluva job and I'm still pleased as punch with it. It was and to some building conservators still is contentious as traditonal restoration aims to reatin as much original material as possible. However on highly used buildings such as these I am of the view that when such structures are life-expired options such as careful recreation, with a full understanding of the materials, architectural detail, integrity and context are weighed against retention (some 15% of the original is still here) then this is a valid approach.
London Underground - reconstruction of South Kensington station faience facade, 2013/14 : new faience block being back-filled
One of the many fascinating projects I was involved in, as London Underground's Design & Heritage Manager, was conservation and restoration of many of the historic structures that the Tube owns and still operates. Out of over 275 stations over 80 are statutorially Listed, including this one, many more are Locally Listed and nearly all have some Heritage Features as assessed by London Underground itself.
Many stations still have faience facades of a type of construction that the Central London Railway (1900) and the Underground Electric Railways of London (1905/6 and later) utilised. The Metropolitan Railway also used faience on many of its early 20th Century reconstructions.
The basic construction methodology is sound - the use of load bearing steel framework and a cloak of effectively mass produced faience blocks - in this case made in Leeds by the Burmantofts Works of the Leeds Fireclay Company. However, some defects can occur if the facade is not waterproof, when moisture meets the steelwork, corrodes and spalls, or if the fireskin of the faience blocks themselves is damaged (such as through hole drilling or physocal damage). The latter tends to invite frost freeze and thaw, further destroying the material.
At South Kensington the issues were compounded by the removal, several decades earlier, of any internal wall finishes when the ticket hall and lift landings. along with the lify shaft, were stripped out for use as a passive ventilation shaft. Some earlier spot repairs, using 'plastic' fillers over wire mesh and coloured resin fillers had also started to fail badly - these tend to be prone to UV failure. All in all the structure and facade was a mess - and first we had to gain Listed Building Consent to undertake intrusive surveys and condition surveys to see what was actually going on.
To cut a long story short we realised we needed to physically reconstruct almost 85 - 90% of the facade, such was the deterioration of the sub-strate and the facade. We had undertaken similar work on other stations and so were able to call on expert manufacturers (Darwen Faience & Terracotta) and construction contractors. The manufacturing of new blocks is not simple as you have to allow for shrinkage in firing, colour matching older and now illegal glazes along with firing temperature variations in colour. To ensure a lack of uniformity - as you don't actually want a 'blank' colour the manufacturer has to also consider glaze weight. The setting out has to be precise - no 'cutting' like tiles, and the new blocks were correctly back-filled with inert packing and tied structurally back to new substrate. All in all - a helluva job and I'm still pleased as punch with it. It was and to some building conservators still is contentious as traditonal restoration aims to reatin as much original material as possible. However on highly used buildings such as these I am of the view that when such structures are life-expired options such as careful recreation, with a full understanding of the materials, architectural detail, integrity and context are weighed against retention (some 15% of the original is still here) then this is a valid approach.