Facade De-Carbonisation – Holland Park Villas – CSI 95%

QSS has scaled new heights to remove stains and protect a £550m development in Kensington, Central London against atmospheric carbonisation. The team used the abseiling technique to ensure a thorough and professional finish.


Project name:  Holland Park Villas

Client:  Knight Frank/Native Land/Grosvenor.

Site:  Holland Park, Kensington.

Project:  Deep cleanse and impregnate over 4,000lm of Honed Branco Imperial Limestone horizontal decorative ledges.

Completed on time and to budget including a 5 Year Guarantee!

CSI Score 95%


This super-prime development completed in 2017 sets a new benchmark for quality.  Valued at £550m this development comprises of 72 private apartments with exceptional interiors. The exterior is elegantly clad in stunning Portuguese Limestone as are the feature window and decorative ledges. After only 2 years atmospheric pollution and Algae was visibly evident from ground level on most of the ledges, also the top coping stones (see lower photo) were contaminated, this issue did not compliment the quality benchmark!



QSS, having previously deep cleansed and protected all the ground level paving including some of the low level Portuguese Limestone planters, we were requested to propose a solution to provide
removal of current, and reduce future, dark atmospheric “carbonisation” discolouration from all 12 vertical exterior facades of the complete building. Organic staining also needed to be removed and subdued. Only 5 elevations could be accessed via a large cherry picker with no other mechanical or plant able to access the remaining 7 elevations.

An effective invisible limestone protection had to be identified and tested. QSS acquired 4 sample stones from the Portuguese quarry, 4 different products were tested and QSTONE S.L.I. was selected as the most effective.


The agreed option was to utilise Rope Access and to Abseil down the facades from roof mounted man safety rails.  To cleanse all the ledges necessitated pumping adequate volumes of hot water up 30m to the roof level, across the roof 90m and reach down 30m to ground level of the furthest elevation. All ledges were hot, low pressure washed, to remove atmospheric, and kill organic, staining, once dry, the Abseilers then low pressure applied QSTONE SLI Invisible impregnation, then an application of QCIDE, both to help reduce future staining and ease future cleansing.


Client testimonial

We are very pleased with the end result, the building now looks fresh and clean again, yes, very pleased.



The cleansed and protected ledges remain easier to clean, whilst reducing future staining. Holland Park Villas is again mirroring its Super Prime status in Kensington.

The refreshed Limestone ledges now compliment the development’s new benchmark for quality. Minimal disruption and increased satisfaction to all Clients.

With a 5 year guarantee, QSS completed the project on time and to budget!