28 Feb 7 potential problem areas that MUST be looked at
With roofs, a lot of the time it’s a case of out of sight, out of mind. However with the health and safety of those using the building at stake, roof maintenance is crucial and can’t be taken for granted.
Working on the ‘stitch in time saves nine’ principle, R&BS is proud to point out the potential problems and pitfalls associated with a roof inspection, namely:
Signs of hidden corrosionCorrosion often occurs on metal roofing areas especially when the protective coatings wear off the roof sheeting. This can be because of age, damage, exposure to corrosive substances (e.g. salt) or dissimilar metals. It is often accentuated in areas that are covered such as apron flashings, and where a build-up of residues can gather such as dust, dirt, leaves etc. This allows moisture to be trapped in the residue and creates a perfect environment for corrosion to occur. These areas are often very hard to see in the initial stages with a visual inspection as they are completely covered. However experienced professionals know to look for things such as geographic locations, staining of roof sheeting at flashing turn-downs, and discolouration of roof sheeting/flashings etc. These can all point to the presence of concealed corrosion, or even corrosion on the underside of the roof sheeting. Early identification of these serious maintenance issues allows for the treatment of these areas before extensive and costly repairs are required, or irreparable damage occurs.
Deteriorated seals and sealantWindows, doors, expansion joints, roof flashings, roof penetrations, skylights, and ventilators all rely on the use of weather-tight seals to prevent the ingress of water. These seals can consist of pre-formed rubber, Silicone, Polyurethane mastic etc. – all with a life span that can range from 12 months to 10yrs+. As these seals reach the end of their life span they will start to crack, perish, delaminate etc. and the effectiveness of their watertight capabilities will seriously diminish. Realising that these seals are reaching the end of their life span is often hard to identify as the visible changes can be very minor. A hardening of the products or a reduction in their flexibility is often the first and only sign. Even after the discovery of internal water leaks from these areas, an untrained eye will often not associate the water entry with these areas because of the very presence of these sealing materials. However experienced professionals will understand the relevant life spans of these products and the early signs of deterioration to these areas. That’s why it is vital that only the highest quality products are used in the maintenance and repair of these areas to ensure the long-term waterproof integrity of these seals.
Incorrect or poorly fitted flashings (particularly around vents, chimneys, etc.)Many roof edges, roof penetrations, adjoining structures and parapets have thin (normally) metal flashings placed around the perimeter or adjoining faces of the area. These are designed to divert water away from the join. Often due to a lack of understanding of weather sealing, poor workmanship or changes in the structure during the life of a building, these flashings are incorrectly fitted/designed and are a common cause of water leaks. These flashings can appear visually adequate, but an in-depth knowledge of the hydraulic drainage of these roof areas could lead to the discovery of inadequate flashing details that are contributing to the water ingress.
Waterproof membrane deteriorationMany different kinds of waterproof membranes are used on flat roof areas (built-up roofs), balcony areas, service/plant areas, wet areas, landscape areas, garden planters and the like. Depending on the application, these can be liquid type membranes (acrylic, polyurethane, bitumen), sheet type membranes (reinforced bitumen, TPO and PVC), epoxy coatings, cementitious type (water stop slurries/beddings) to name a few. Each of these membranes has its own unique characteristics as they start to deteriorate. Professionals with a long experience in the use and performance of these membranes can identify what may be happening maintenance wise with these membranes before any faults are apparent. As always, it is essential that there is a thorough understanding of the existing products that have been used, before any patching, replacing or maintenance works are carried out.
Surface cracking, blistering and crazingBuilding facades, dividing wall areas and parapet wall areas are often coated with external grade coatings or decorative membranes. These are often applied over the top of acrylic renders. Cracks, blisters or crazing to these coatings, although often appearing minor, are normally indicative of moisture ingress into these areas. This can often lead to water tracking behind the associated renders or wall substrates and then causing leaks. The leaks can often compromise the waterproof membranes or flashing details if the roof area is below the leaking wall areas. Also if moisture breaches these wall areas, it can affect the structural components of these areas. For example, steel reinforcing bars can cause corrosion and concrete spalling which in turn can lead to a weakening of the building’s structural integrity. The identification of these potential issues and the monitoring of the integrity of the wall coatings before serious issues occur is essential in preserving the waterproof and structural integrity of all structures.
Loose tiles, cracked pointing or valley gutter drainageRoofing tiles come in different materials (Concrete, Terracotta (Clay), Pre-formed metal) as well as many different styles, shapes and colours. Although a lot of tiles utilise the same watercourse drainage systems and fixing methods, there are many subtle differences across the vast range that can often cause water ingress into buildings. Construction methods also can play a big part in the reasons why tile roofs are leaking. It could come down to the design of the tile fixing clips that are used, the presence (or absence of) an under-tile sarking layer, inadequate or blocked valley gutters and absent or blocked ridge drainage holes. There are often many ‘generic’ type issues that can effect tile roofing areas such as cracked pointing or delaminated ridge bedding, cracked or broken tiles, unsecured or slipped valley tiles, cracked flashings etc. and although these are relatively easy to identify in a visual inspection, access to these types of roofs is often extremely hazardous, due to the roof pitch and the slippery and sometimes fragile nature of these areas.
Blocked or overflowing guttersMajor water leaks can occur from the overflowing of roof drainage gutters, especially internal box gutters. Often this occurs when there are large volumes of water dumped onto the roofing area during a weather event. This can overload an inadequate drainage system with no overflow diversion facilities. Or perhaps the drainage of the guttering is blocked by debris collecting in the outlet. Often by the time an external inspection can be carried out, there are very few obvious signs that the overloading has occurred and it is only an experienced eye that can identify the characteristics of an overflowing event. These characteristics can include the volume and position of the internal water ingress, design characteristics or faults with the guttering system, discolouration or ‘wash’ marks on the external of the guttering surfaces. The effective rectification of these issues is a specialised area that requires experience in dealing with these issues in many different applications.
You can read more about our roof repair and maintenance service or call now for a quote on 1800 550 037.