Maverick Maintenance & Makeovers recently undertook a roof inspection of a property in Osborne Park to ascertain where rain water was entering into the ceiling space. The building in question is a two storey residential complex of twenty units with a flat steel roof, pitch of less than 5 degrees. Residents were complaining of intermittent roof leaks appearing without warning in various parts of the roof. As a result of this inspection we reported the following findings:
1. The roof fabric was inspected overall for areas of water ingress and possible design and construction issues.
2. Box gutters and downpipes were inspected for blockages. Minimal debris was observed in these areas. No blockages were evident in the downpipes, collection boxes or rain heads.
3. The box gutters appear to be of ample size to accommodate a large volume of rain water. Notwithstanding this, overflow pops are located at the end of each unit run. These overflows were not blocked or restricted. These too were of adequate size to allow quick evacuation of rain water and designed to operate when water was at approximately half way up the total height of the box gutters.
4. After exhausting all possible areas of water ingress, attention was turned to the installation of the steel roof sheets – what was immediately evident is the fact the sheets have been overlapped incorrectly, with the top side of the lap facing in a westerly direction, towards the prevailing weather from the coast. However, of more concern is the installer has failed to allow for capillary action of rain water on low pitched roofs.
5. In heavy rain conditions, the surface tension of the water running over the edges of the sheets is enough to allow the water to drive uphill and along the sheets until it finds a point of exit.
6. Several roof sheets were lifted for evidence of moisture. The below photo gives a good indication and visible reference of water travelling uphill along the inside of the sheet and its exit point into the roof cavity.
7. Anti-con was cut into and moisture was detected in between roof timbers and insulation batts above the plasterboard ceiling.
8. As a result of the inspection, all roof sheets were lifted and the overlap corners cut to prevent capillary action along the sheets.
Conclusion
The intermittent nature of the roof leaks to this complex appear to be linked to the installation by the builders roofing contractors. Leaks of this type do not occur all the time when it rains and can reply upon the right weather conditions, namely wind direction and how heavy the rain fall is and dirt build up along the overlap lip over time.
Phone 6118 2744