A common sight…a ‘hole’ in the roof with pipes, cables and ducts coming out of it and heading off to their respective rooftop destinations.
The ‘hole’ has an upstand around it to stop water draining into it and is probably covered with tarpaulin to keep the building dry during rainy periods. Hopefully, there is a barrier around the ‘hole’ too to stop any person from falling into it.
- The roofing contractor has completed his work, the roofing membrane has been neatly detailed to stop at the top of the upstand in accordance with the roof system manufacturer’s warranty. A job well done!
- The M&E contractors have made a very neat job of running the pipework out of the hole and in the appropriate direction on various cable trays and other containment.
- The main contractor realises that he has an issue affecting the build programme so has arranged some temporary weathering until the problem is fixed.
- The architect is rightly concerned that this detail is weathered properly as it could compromise the integrity of the roof, arguably the most important part of the asset he has designed and is responsible for.
This very important detail has escaped the bill of quantities to date and is absent from any contractor’s package but something must be done.
So what next…
Invariably, due to cost implications, the ‘dog kennel’ approach is adopted with varying degrees of success. At best, a thermally insulated structure is constructed around the service penetrations to seal off the ‘hole’.
The roofing contractor returns to site to then weather the structure. At worst, and as is often the case, an uninsulated cover is formed to keep the rain out of the building. Whilst it is weatherproof, it is not necessarily airtight nor indeed proof against insect and vermin entry.
It is unlikely that either carry the roofing warranty and it is also likely that solution may leak in the future following heavy storms and winds. And when it is all finished, the M&E contractor wants to run some more pipes through the same hole.
The proactive and collaborative approach…
Ideally, the issue of roof penetrations should be addressed early in the building journey from conception to the built article. The later in this journey it is addressed, the more likely an unsatisfactory result when the services get to the roof.
Considering this issue at design stage means that this important detail can be costed in from the start and given the attention it deserves.
As with the whole build process, collaboration by the relevant parties is a vital element in this process:
- Input from the project’s M&E design consultant will normally provide valuable information on the sizes of the roof penetrations that will determine the size of roof opening and also inform the type of weathering that is appropriate.
- Collaboration with the roofing contractor at the earliest stage possible will also ensure that the roof system used is allowed for in dealing with this issue. Typical factors to consider are the roof construction type and the proposed weathering system, kerb constructions and whether these upstands are insulated internally or externally.
- The Main contractors will also be able to look at how the roof openings can be made safe as soon as they are constructed.
- From the M&E contractor’s perspective, programme is a vital element. At what point can they exit the roof with their services that respects the solution decided most appropriate for the situation?
The above considerations will be much more likely to deliver a solution that is purpose made and appropriate for the intended purpose. Issues relating to thermal efficiency and airtightness can be addressed as can considerations relating to safety and programme.
The result should be a housing which is purpose made and has a performance and a design life to match that of the building.
The cost implications being covered early in the process mean that corners do not need to be cut to get the building operational and weatherproof. A well designed solution will also cope with additional services run at a later date.
“When it comes to the roof, a proactive and collaborative approach will provide many benefits to all the concerned parties”.
Nicholson Roof Products
The ROOFBOX® weathering system for service penetrations provides a proprietary and guaranteed solution to the inherent problems associated with bringing pipes, cables and ducts through the waterproofing layer at roof level. These insulated aluminium units are powder coated and provide an alternative to the traditional ‘dog kennel’ approach to weathering services as they exit onto the roof.