Q My home office overlooks a flat-roofed extension. As I am spending so much more time in it, I would rather like to have a green roof or sedum roof rather than the ugly asphalt that is there now. What are my options and what should I expect to pay?
A With the current 'emergency measures' continuing for the foreseeable future, a large number of us are now becoming accustomed to new working arrangements. Our architectural practice is no different, with all staff entering another week of the new 'work live' arrangement.
Although this new working environment can be challenging, it also allows us to experience our home and its environs in different ways.
This can vary from seeing how light falls on certain surfaces during the day to chatting with previously unknown neighbours, albeit from a safe social distance.
The extended period spent at home can also highlight areas of improvement or changes that we may have been thinking about for some time. Our new workstations are often situated with views over neglected green spaces. Indeed, many of us have dusted off our green fingers and taken to the outdoors, partly as an act of self-preservation but mainly to improve the open space around our home. However, should the view from your new home office be of an ageing asphalt roof, there are options for creating a 'green patch' here.
Green roofs, generally referred to as 'extensive green roofs' in domestic situations, are growing in popularity. They are a natural form of roof covering, which use low-maintenance planting that is tough enough to survive relatively extreme weather conditions such as drought, sun, wind, frost, etc. Green roofs are generally planted with sedum, although wildflower is a lesser used alternative. Sedum is a perennial plant with many different varieties, most of which change colour during the year, thus providing an evolving palette with each passing season.
Apart from the visual interest and aesthetic qualities that a sedum roof provides for those living in the house, it also provides many benefits to the biodiversity outside the house.
The smallest of sedum roofs will provide an undisturbed habitat for a vast array of nature's species, helping to shelter and increase their levels over time. It also acts as an important water attenuation mechanism, slowing the rate at which the rainwater leaves our roofs and enters the public drainage system. Green roofs may also extend the life of the roof waterproofing membrane as it offers protection from damaging UV rays.
When considering changing an existing flat roof area to a new sedum grass roof, there are several criteria which should be examined. While the term 'flat roof' is often used, these types of roofs are always installed with a minimum fall to ensure adequate water run-off. Sedum roofs can be installed in roofs with a pitch up to 45 degrees, although there is substantial additional work required to anchor the sedum roof build-up as the angle of the roof increases. The condition of the existing roof should be assessed by a competent professional, as it will need to withstand the imposed load of the structure, the composition of the new green roof and also any loads due to maintenance, etc.
It is important that a suitable waterproof membrane, compatible with the sedum roof, is installed to reduce the chance of water ingress. The introduction of sedum on top of an existing flat roof may provide an opportunity to introduce additional insulation. The insulating layer can be designed to introduce minimal falls or simply to protect the existing roofing membrane. In addition to being visually attractive and providing a new wildlife habitat, your new roof can assist in reducing heating bills and reduce your carbon footprint.
While sedum roofs are low maintenance by their nature, access will be required to check items such as drains and the general condition of both the roof and planting. At the design stage, it is important to consider the health and safety aspects of the installation of a green roof, including suitable safe access during construction and for the lifetime of the roof.
The current guidance available for the cost of supply and installation of sedum green roofs is between €175/sqm to €200/sqm. These figures will vary depending on local conditions such as quantities, site access and roof configuration.
When choosing a contractor, you should always insist on speaking to previous clients, and visit the completed works, where practical. It is also critical that the relevant certification and guarantees should accompany any sedum green roof system. Your RIAI registered architect will guide you through the details regarding this.
None of us know how long the new working arrangements are going to last. For now, those who are lucky enough to have a room with a 'green view' will testify to its benefits. If you are one of those that have been dreaming of changing that view, now might just be the ideal time to act.
If you are considering changes to your home, work with a registered architect. Find one on riai.ie, the registration body for architects in Ireland.
Michael Carroll, registered architect, member of the RIAI, director and co-founder of Horgan Carroll Architects, will be participating in this year's RIAI Simon Open Door, details at simonopendoor.ie. Visit horgancarroll.ie for details and check out @horgancarrollarchitects on Instagram
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