Copings protect the top surface of parapet walls, a vulnerable space in your building due to the fact that bricks are porous, and water can seep into the structure. This issue must be resolved quickly, or it will lead to mould, damp, rot, or damage to your roof and building.
The coping allows water to run-off the top and about 2 inches down the sides of a parapet wall. In this article, we will discuss five concerns to consider when specifying a wall coping for waterproofing your parapet wall.
#1 The Environment
Environment includes wind, rain, sunlight and temperature range.
With wind, you must consider the strength of it at the height of the roof. Gusts of wind in the UK have been recorded as high as 150mph. This is a particular problem in exposed locations, especially along the coast.
Knowledge of the maximum peak wind speeds to be expected informs how the coping should be fixed to the wall. A strong coping attachment must be considered.
Rain is also something to consider, especially as the point of a coping is to protect against water. You should consider if water will pool at the roof, whether an incline should be used to divert it, as well as the function of the coping in this scenario.
Wind can blow rain horizontally and even upwards, so your coping must be watertight to the wall and protect against this.
Sunlight and variation in temperature are particular challenges when using metal copings. Thermal expansion and contraction must be factored-in to both the fixing methods used and the joint design.
#2 Durability and Maintenance
No coping will last forever, but some will go longer without maintenance than others. You should make sure to choose a coping depending on the opportunity you will have to carry out maintenance and where maintenance will be hard to do, greater priority should be given to low maintenance coping systems.
Stone, tile/terracotta and lead have long been standard choices for copings. Each can provide an attractive look but can have certain drawbacks. All three are heavy material choices and tile and stone copings usually involve mortar in their fixing which can suffer from freeze-thaw damage.
Additionally, these materials are hard to cut or shape on-site and lead is quite often victim to thieves.
GRP and Polymeric copings are lightweight and can be shaped in a variety of shapes. Unfortunately, these material choices can deform under heavy loads due to their limited strength. They are also vulnerable to UV deterioration.
Metal copings are a very popular option as they have more strength.
Mild or plain-steel is also an option but corrosion can be a problem with rust streaks being unsightly on buildings.
Likewise, copper is attractive when first cut but oxidizes with a layer of green verdigris. (Modern alloys and coatings can postpone oxidation but not prevent it entirely.)
Aluminium is naturally corrosion-resistant and is also easily fabricated into whatever shape a coping project could demand. Once installed, it is then strong, durable and wind-resistant, and exceptionally long-lasting.
Additionally, aluminium copings have a reduced need for regular maintenance due to their tough structure. Aluminium has a higher specific strength (strength per kg) than steel so copings made only 2 – 3mm thick are strong enough to resist deformation.
This makes any aluminium coping and capping system a protective and long-lasting system for your building envelope.
#3 Aesthetic & Visual Requirements
The parapet wall is an architectural feature that is often highly visible. Depending on construction, one or both sides may be visible from the ground. The top of the coping may also be observable from a taller adjacent building.
For certain buildings, it may be necessary to use specific materials and colours for coping. As an architect, you will have ideas for how the coping should look in terms of shape, colour, texture and material and modern materials and painting/coating techniques provide a far wider range of options than was previously the case. To give one example, a metal coping could be coloured to either match or contrast with window frames or fascia materials.
Fixing method also has a bearing on appearance. Simple cappings or copings may have fasteners into the side of the wall that are visible from the ground. Some manufacturers produce capping and coping systems where fasteners are hidden from view.
At HJA Fabrications, our aluminium wall copings can be fabricated using a concealed fixing. This gives a crisp, clean edge to your coping system as the fixing is out of sight.
HJA Fabrications: Specialists in Aluminium Coping Systems
Many options exist for coping. By considering the building environment and location, plus visual goals, construction costs and maintenance needs/frequency, it’s possible to narrow the list of candidates.
Unless stone is required, metal copings are often the most appropriate. Of the range of metals available, the most versatile and often most appropriate is aluminium. Why not read next 5 advantages of specifying aluminium copings!
At HJA Fabrications we produce an extensive range of aluminium copings along with related rainwater and gutter products, soffits, fascia pieces and cladding. Learn more by calling us on