Today we battled Mother Nature. We were doing modifications to a tar and gravel roof in Vancouver. Three new plumbing vent stacks and elimination of two old ones. We put down two layers of torch-on on the old holes and stripped in the new vents with two ply membrane also. Problem was the roof held water. We had to keep the vacuum fired up for the hole job keeping the water from seeping into our work area. Is summer gone already?
Today’s blog takes us to Annacis Island situated under the Alex Fraser bridge between Delta, Richmond and New Westminster BC. The worst case scenario leak occurs on a flat roof with external drains. External drains mean that the drains are located outside of the building’s perimeter. So the roof sags, in the middle, over time and the drains remain a high spot on the outside edge of the roof area. Complicate that with an old tar and gravel roof and you have a leak that can fill a bucket faster then you can empty it. Good thing this leak was just in a metal shop and not over some computer warehouse or something like that. A lot of water was getting in. We shoveled. We swept. We blew water. We found the problem and dropped some clay on it. Now we just need the roof to dry so we can upgrade the temp patches to a more permanent torch on status.
A tar and gravel roof leak, in the general field area of a roof, can be a tricky thing to find. For starters, the crack or split in the roofing felts or roofing plies is concealed by a flood coat of asphalt and the ensuing gravel broadcast into that. In addition, there will be general and common debris such as dust and dirt, rain pollutants, tree droppings and anything else you might find on a roof. (You’d be surprised at what we have found!). These “additives” are commonly sunken into the spaces and gaps between the rocks in the built up roof system making it even more difficult to see a deficiency. Whether it is a 3 ply tar and gravel or 4 ply T&G roof system, the point of entry or stain on your ceiling is not necessarily exactly below where the leak in the roof is. Water travels. It takes the path of least resistance and escapes the attic or ceiling space through the easiest port. In bedrooms, it’s usually through the light fixture and in bathrooms it’s the skylight or the fixture again. It occasionally even runs in-between walls and skips a floor!
If the leak is in a commercial building where the roof deck is something other than wood, such as metal or concrete, the task of finding the leak just got more difficult as the water can travel substantially further on those decks before it drips out and gets the floor wet so you can notice it. I recently had a leak that travelled over 60 feet in the flue of the metal Q-deck. I deserved my star on that one
There is no rhyme or reason where a split will occur. It can be in a seam or junction of the plywood, shiplap wood deck or roofboard (also known as donnyboard) used underneath the tarred roof system. The hole or leak can also be situated on the laps of the roof plies from when they are initially mopped down with hot tar.
For a proven track record of finding leaks contact Crucial Roof Services – Your Lower Mainland roofing service provider.