Commercial Roof Assessment, Roof Repair and waterproofing – An Case Study
The example listed below is indicative of a typical roof assessment and recommendations pertaining to commercial roof repair.
A full assessment was carried about on a commercial building complex in a neighbouring state to determine the points of water ingress, assessment of damage and evaluation of possible future problems related to the leakages. Our assessment included evaluating the performance of the existing roofing system to determine whether it was performing according to its specified function as well as identify failures which would inform possible future remedial action.
The building complex was 28 years old, featured a pitch type roof and the roofing material used was pierced fixed, Chromadeck type steel sheeting which had been replaced in 6 years earlier. Some roofing areas included polycarbonate sheeting, all of which ran into conventional box type gutters.
The assessment was conducted primarily by a on site, walk around inspection of the roof surface area as well as by using a FLIR Thermal camera. The following were inspected and assessed:
- Condition of the Roof Sheeting
- Roof Fasteners
- Flashings and gutters
- Roof penetrations
- General environment and
- Potential plant processes that could impact the viability of the roof and it’s supporting structure
Findings and their respective recommendations were broken down item by item so as to enable the complex’s owners to make a decision with regards to repairs and proposed budget allocation as well as time scale set for the repair and whether this would be done in stages or not.
Roof Assessment and Repair Recommendations
The findings included extensive mechanical damage to a large portion of the roofing material. There was also obvious signs of corrosion with areas surrounding steam venting systems particularly badly affected. Areas of the polycarbonate sheeting appeared to have suffered mechanical damage due to extreme wear. The roofing material’s heat retention was also found to extreme measured at 60.1 degrees Celsius at only 10H00 am.
The roof fasteners were found to generally be in a good condition with a small number requiring replacement as they were either loose, non existent or miss installed.
Flashings, closures & gutters were found to be in good condition and installed correctly thereby preventing water ingress. Some corrosion was detected on large sections o f most box gutters. Some blockages of down pipes was detected.
Roof penetrations for equipment such as roof extensions, ventilation fans, evaporator cooling units, steam exhausts, lifeline anchor points, roof irrigation and pipes which are located on the roof have the potential to cause enormous damage where these are not laid out, or installed correctly. It was found that many of these penetrations were problematic and allowing penetration of water. The roof coating around these penetrations were almost without exception, corroded. Sections of the factory roof showed clear signs of damage in proximity to steam outlets and vents.
Environmental factors also need to be taken into consideration when designing a roof structure and to this end the client’s roof was found to have suffered from the corrosive factory environment such that certain sections of the interior roof supporting structure had also been dangerously compromised.
The lifespan of any roofing structure correctly treated with a suitable waterproofing and coating system will be extend. It is critical that the correct roof waterproofing system is specified and that this is applied by skilled and competent contractors. An analysis of the existing waterproofing coating system showed that the system was failing, with delamination and brittleness seen throughout the roof exterior surface. The DIY type products used by the previous contractor were clearly inadequate for the industrial application within which the roof had been installed. Some of the previous waterproofing work was found to also be exacerbating the problem of water ingress in certain areas. It was also found that silicon was used which should be avoid at all costs on roofing applications.
Finally roof structures such as skylights will inevitably cause problems at some point in the future. In this case it was found that there were numerous problems that would always be a difficult fix because of the nature of the installation. Various top plates were corroded leading to a dangerous situation where people could slip and fall on puddles of water every time it rained.
Commercial and Industrial Roof Repair – Recommendations, A Case Study
The following recommendations were made in order to repair and waterproof the industrial complex’s roof:
It was recommended that the existing industrial steel roof should be coated using a roofing coating system that offers increased chemical resistance while still being flexible enough to cope with the high UV rating for the area . Additionally, a light coloured coating was suggested due to it’s increased reflectivity so as to assist with the cooling of the interior factory area.
Building maintenance staff were to be trained in the 90 degree roof access method developed to minimise damage to the roofing structure caused by not maintain the weight on the roof fastener line only. Safe walking areas were to be highlighted using a different colour or installing structurally light walkways. Maintenance staff should also be educated on the consequences of dropping equipment on the roof and the effect it has of weakening any future roof coating system. Any service equipment that needs to be located on the roof must be securely bolted to the roof or movement could again weaken any future waterproof roof coatings.
Roof sheet overlaps should also be sealed to prevent the ingress of dirt which itself can cause friction thereby weakening the coating.
Steam venting ducting systems are to be extended so as to disperse potentially corrosive steam and exhaust fumes safely away from the roofing system. Obviously these vents should be located well away from the more delicate polycarbonate sheeting.
Where polycarbonate sheeting is used, their lengths should be shortened.
Roof fasteners must be inspected regularly and problems identified individually. Existing roof fasteners should be replaced with galvanised fasteners that have a more aggressive thread enabling greater adhesion. Rivets should not be used to secure roof sheeting. Bonded EPDM washers are recommended using all existing fastener holes.
Where services require that a pipe or reticulation services is required to penetrate the roof structure, be sure to use existing perforations or consider re-routing the services such that no new penetration are required.
Waterproofing Roof Flashings, Ridges and Downpipes.
Steel sheet roof ridges are not designed for foot traffic and this should be avoided. Prior to the application of any future roof waterproofing, all flashings, and roof closures should be repaired to prevent the ingress of water.
Gutters and box gutters should be cleaned frequently and all downpipes should be checked for blockages. All gutters should be checked ensuring that they have been installed at the correct level or slope. Ideally downpipes should be of the largest diameter feasible so as not to obstruct the flow of water during unusually heavy precipitation events. Ideally there should be a minimum of a 75mm diameter downpipe for every 40m2 of roof area.
Any roof ventilators that are not operational should be repaired and waterproofing of the installations should be prioritised. Where roof ventilators exist, be sure that they are kept clear of dirt as this could also hasten the erosion of any waterproof roof coating.
Roof penetrations and general area.
Where roof irrigation supply pipes exist, ensure that anchors are properly secured to minimise any movement due to the hammer effect for example thus preventing abrasion and chafing of the waterproof coating system.
Where water pools on a concrete roof, a lightweight screed can be applied to ensure that water flows away from low areas thus preventing future corrosion.
Where the interior of a roofing system will be subjected to the effects of chemical processes, it is recommended that the interior of the roofing structure also be coated with a suitable coating that is chemically resistant. It is also important to regularly clean the interior of the roofing system in order to prolong the longevity of roof.
Industrial Roof Repair and Waterproofing Systems
For best results an experienced, professional waterproofing contractor should carry out the repairs and roof waterproofing as per specification. This way the client has peace of mind of a job done well and can take advantage of the contractor’s warrantee should something go awry. Mpumalanga Rubber offers an unconditional 10 year workmanship warranty.
In this case the following Liquid Rubber products were used
- The Sealant used was Liquid Rubber CPC-550 sealant reinforced with Fibretex WP-90 reinforcing membrane. This was applied in three layers to all sheeting joints, flashings, to seal holes, and was also applied as a lining to the interior of the box gutter.
- The Primer used was Liquid Rubber BLD-001 which was applied over suitably prepared roof surface area e.g. HP Washed with proper detergent, swept using soft bristle brooms and cleared of any other foreign matter.
- In preparation for the application of a Primer, Liquid Rubber BLD-001, the roof surface was washed with a high pressure washer using detergent afterwhich all surfaces were swept clean.
Finally a waterproofing and protective coating was applied over the primer being Liquid Rubber WSC-700. A minimum of two coats applied to a steel roof are recommended, three would be preferable. Different coloured coats are recommended thus ensuring a 100 percent covering. Obviously no coating is applied to the polycarbonate sheeting.
Walkways using a different colour were demarcated using Liquid Rubber WSC-750 over the waterproof protective coating to delineate areas suitable for foot traffic. This product has a slip resistant granular finish making it ideal for foot traffic.
Skylight joints and steel plates were sanded to remove rust and properly cleaned thereafter in preparation for the application of the waterproofing system.