Mould and Roof Leak Roof Inspection

Case Study

Here is one area of staining/growth on the underside of the plywood deck. This is the area where the bathroom fan was not properly ducted and vented. The fan issue alone can be blamed for adding moisture into the ceiling space and is probably the primary cause of this situation. If this was the only occurrence location then we could rest relatively easy knowing the condensation issue was only due to the improper fan ductng. But it is not. We witnessed a separate instance of deck dry rot caused by condensation over by the entrance to the bathroom. Several joist spaces away.

Here we have the fan from the bathroom below going up through the wall and exhaustng into a proper roof vent. No concern here.

This is the staining over the entrance door to the bathroom. Typical to that of dry rot/condensation issue.

Roof area over 305. The ponding water accelerates or increases any probability of condensation occurring due to temperature transference. Puddles of water are the coldest object/surface on a roof. That cold temperature is transferred to the ceiling space where there is no air movement. Warm meets cold and turns into moisture vapour which sits on all surfaces. Extended moisture dwelling results in organic growth. Ponding water is inevitable on this roof ( in a couple select locations) but keeping the drains clear would reduce the size of puddle.

We cleared the drain blockage

There are plenty vents on the roof for bathroom fans and kitchen hood fans. We just don’t know if all are fans properly “ducted”.

East side of roof. Two puddles join. The one over 305 and the one on the east side

Here is another “unavoidable” puddle on the NE corner area

This is overtop of 303. A vent with a hole in the deck but no pipe. You can see down into room below. This isn’t really an issue but it would be best if they could cover up the hole in the ceiling. That way no warm air escapes the room and possibly enters the ceiling space

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Gooseneck vent for a clothes dryer vent over 305 is not appropriate. There is no way to clean the bug screen of lint. (it does not have a removable lid. 2 problems - The dryer will loose efficiency when the bug screen is entirely plugged up and the warm moist air will then be sent into the ceiling space. This needs to be changed to an 8x8 birdhouse vent. It will then duplicate all other clothes dryer vents on the roof.

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We did find a soft spot on the roof caused by condensation and dry rot. Randy is standing at the edge of it in this photo. It is over 305. Close to where his closet is (that has had brown drips come out of the ceiling in the past). Most of the soft spot is under the ponding water and that is understandable (water is colder then anything else around it thus encouraging condensation below) however it is not a big roofing concern. The roof membrane is still watertight and should last many more years.... perhaps 15. It can be repaired but is not required.

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To repair we would remove the area of dry rot, replace the plywood deck, install new membrane and install a ceiling space vent over the area to try and reduce the probability of condensation returning. Again.... Not entirely necessary for roof integrity but it might get rid of the dripping 305 gets in the closet. This condensation should only be “active” during the colder months. Condensation does not happen when there isn’t a temperature difference between inside and outside.

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Sample of a clothes dryer vent and the ease at which it can be cleared of lint. We did this cleaning to all dryer vents.

Customer: Collingwood Gardens
Project Completed: March 2015
Type of Roof: torch on membrane
Materials: n/a
Location: 3506 W 4th Ave, Vancouver

On this job we were called out to remedy a condensation and mould issue that stemmed from a roof leak and venting problems.

There was staining/growth on the underside of the plywood deck. Ponding on the roof increased the possibility of condensation occurring due to the temperature transference. That cold temperature was being transferred to the ceiling space where there was no air movement. Warm meeting cold turned into moisture vapour which covered all surfaces. The extended contact with moisture resulted in organic growth.

We cleared the drain blockage. There were some vents that needed to be changed. We found a soft spot on the roof, caused by condensation and dry rot. The roof membrane was still watertight, and could last another 15 years. We recommended a repair in which we would replace the plywood deck in the soft area and install new membrane, with a ceiling space vent. This would repair the structural damage and should prevent a recurrence.