Pullman London St Pancras – Roof_Case_Studies-v2 | Page 2

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With the support of the product manufacturer , they satisfied themselves that the roof and their system were compatible and designed the build-up of the new system to help minimise the client ’ s need for major maintenance in the future , whilst providing a 20-year guarantee across the roof .
With all elements of the project now agreed and approved , the replacement of the roof could begin , with each section being stripped up , waterproofed and then replaced and the surrounding materials repaired where needed . This was to ensure that the overall roof , including areas and materials that we were not replacing , provided an overall watertight seal .
Working methodically , the teams progressed well across all of the roofs that were being replaced , ensuring that each day the areas beneath were sealed and free from water ingress . The project was not without its challenges , including the centre section being heavily built-up with plant , BMU tracks and steel work criss-crossing the roof with little clearance in some areas . This led to the project being slower than normal , but this had been factored in and discussed with the client . The other main challenge of the project related to the great British weather . The project began during one of the windiest and wettest summers in the UK , needing us to ensure that at all times the roof was sealed and no opening up took place if rain was expected . All materials had to be stored safely to avoid anything having a risk of blowing off the roof , including the design of a safe system to transport any materials around the roof .
Finally , with the upper roofs complete , we have now been awarded the work to undertake the replacement of the lower roofs , helping to bring these other areas in line with the future vision for the client .
Our work included :
• Initial test trials with the product manufacturers to ensure that the correct product was specified and would provide the client ’ s desired level of cover , including cross-hatch , adherence and core sample , avoiding the potential for early failure and any future warranty issues .
• This phase of testing and trials also allowed us to understand the current build-up of the roof system and plan for any changes to align the systems with current regulations .
• With the roof being open to the elements , there were areas that were attractive to birds and the deposits that they often leave behind . Each of these areas had to be dealt with safely during the removal of these deposits , including the initial neutralisation of the deposits , then each section being carefully removed and disposed of within hazardous waste procedures , with the team being fully suited and kitted out with the appropriate PPE and RPE for the task .
• The current system was completely stripped up , taking the roof back to the exposed deck , from which we could then begin replacing the manufacturer ’ s approved coating system .
• Through the initial trials , we were able to provide the understanding of which areas were damp and any areas that were dry , with the ultimate decision being to replace all areas of the roof , thus ensuring a full warranty throughout .
• As is the case with any internal or external project that required the removal of coatings , we could not be sure that 100 % of the substrate would be sound until it was removed and we advised the client accordingly . Thankfully , during the initial strip-up of the current system , no adverse issues were found and the substrate was intact .
• Where repairs were required to provide a suitable surface , these were undertaken in conjunction with the manufacturer ’ s input , ensuring that the materials used would not adversely affect the new system or any warranty provision .
• With the substrate fully prepared and cleaned , the primer was applied to all surfaces and then the vapour layer was laid down to provide the initial waterproofing seal .
• Once the vapour layer was in place , the main elements of the roofing system could then be installed and built-up , which in this specific case included the specifically cut and designed insulation and foaming , the carrier membrane , embedment coat which is reinforced with a fibres to allow movement , and then finally the top coat of the system is applied and built up to achieve the desired thickness .
• Due to the volume of plant and historical pipework that was present across the roof , care had to be taken when working around these systems , so as not to damage any areas . This also meant that where the current roofing system was terminated at masonry and lead work , or beneath pre-built cappings , these had to be carefully lifted and safely stored to provide access for the new system , then each item replaced or redressed to ensure a watertight finish once the new roof system was in place .
• With the size of the roof and again , the volume of plant around the central core , as well as the client ’ s decision to not have a temporary roof fitted , the delivery of the works and the stripping and replacement of the roof had to be broken down in to sections , reducing the potential for water ingress and ensuring that each night the roof was sealed .
• In addition to the upper roofs , we were also asked to review and commence the replacement of some of the lower roofs . Unfortunately these areas had historically been poorly fitted with a felt finish that will need to be stripped and replaced .
Project Challenges
As with all projects , one of the most important factors of the delivery was the health and safety of our operatives . Working 17-storeys above the busy London streets , we were tasked with working closely with the hotels employees and day-to-day operations , planning accordingly to minimise any disruption to ensure that the hotel could operate as normal . Along with these factors , we encountered various challenges throughout the project , including :
• This project , like many similar , included the application of roofing and coating products that had to be undertaken within strict manufacturer guidelines . All of our works delivered throughout a classic British summer which included one of the hottest and also wettest periods , requiring a flexible approach and bespoke delivery schedules to ensure safe delivery and maintain product application in the manufacturer ’ s specified guidelines in order to achieve the desired warranties .
• As the building is centrally located and tall in comparison to its counterparts , the outer edges of the roofs were awash with mobile phone masts . The presence of these masts limited our ability to work safely in certain areas , meaning a proactive approach was required in communications with the mast operators to ensure that they were deactivated each day and a safe system of work put in place to avoid all risks . In addition , some masts required a ‘ lift-and-shift ’, which had to be planned 6 months in advance of the project .
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