BUILDING SERVICES ON FLAT ROOFS R OBJECTIVES


the roof impossible without incredible disruption and cost. Building services engineers are working very hard to reduce the environmental impact and cost of building services with renewable energy, ground source, intelligent controls, etc. How much of this effort is wasted when the roof top equipment has to be decommissioned and moved to facilitate a roofing project? If you are moving a 15 year old chiller to facilitate a roofing project, will it be put back? Or will the unit be prematurely scrapped as a similar installation cost is likely to be incurred within a few years! Will you just patch a roof leak when you have just paid £’000’s to move services? No, probably you will re-roof the whole area 5-10 years before it was budgeted, for the same reason. In a recent Roofing, Cladding and Insulation (RCI) article (Technical Note May 2009) the following telling comments were expressed:


“In tracing the sources of rainwater leaks through flat roofs one of the most common causes is membrane puncture damage resulting from the installation of rooftop equipment. “Adequate space should be provided between the roof membrane and the underside of the rooftop equipment so that proper repairs or replacement can be carried out in the future.”


Hence, supporting services clear of the roof is critical, and not penetrating the waterproofing when supporting services is desirable. We recommend a minimum building clearance for all services of 500mm – we can support at higher and lower heights as prescribed by project parameters, but this we feel should be the project team’s aim.


Free-standing supports have now been around for some time. Ensuring that the support method is appropriate to the roof build-up is critical. Roof-Pro has over 15 years experience of working with building services consultants, architects and structural engineers to help determine the correct method for supporting services on flat roof plant areas.


Roof assemblies (structural deck to waterproofing) are varied with differing membranes, thermal insulations and structural decking. The assessment of waterproofing assemblies when loading support bases is on two counts: 1) Can the thermal


insulation/membrane take the permanent calculated loads with a safety margin?


2) Are the point loads from a structural


decking and beam point of view acceptable to the structural engineer?


Some light-weight structures or structural decking are designed to take only minimal loadings, but depending on the services mass being supported, targeting above internal structural beams, nodes or load bearing walls may be possible.


Hence having a specialist support company looking at these criteria is a key benefit, with an in-house design team who can provide load management calculations for the project structural engineer’s approval. Roof-Pro can provide all of this information to the project team. Principally service installations on flat roofs should be installed to permit future access to the waterproofing membrane for renewal and maintenance. Installing condenser farms in large areas where the


Building & Facilities Management – December 2010/January 2011


density prevents access, or where AHU, chillers, pipes and cable tray are supported too low, should not be acceptable. It is usually the end users, the building owner or developer, who picks up the cost for this poor approach.


The critical design criteria are load management, stability, and building clearance. These criteria, not by chance, are encompassed in Roof-Pro’s 3.Point Certification. Consultants and building owners should request 3.Point Certification to ensure the build team delivers on the objectives of Roof-Pro Systems.


If the project design team consider all of these key issues and choose the correct support method for that roof build-up, it can save the building owner a lot of money and problems later on in the building’s life. Tel 01234 843 790 www.roof-pro.co.uk


feature :: building & refurbishment 15


Building & Refurbishment


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