Decks Need Strength

September 14, 2020 Laura MacCormac




Two Purposes: Roof and Deck

Roofing GTA
Decks are part of the roof because they protect the area below them.  They are designed to function as a roof with extra capacity for human traffic and all the heavy things that get piled on them.  So really, the deck provides two functions: a roof and an outdoor space for people. That is why they need so much strength.

Leak from a Deck

Earlier this year we attended a leak into a resident’s living room. There were buckets on the floor catching the drips which were coming down with increasing speed from the ceiling.  It appeared that water had accumulated above the ceiling for quite a while and caused the wood above to swell.


It took time for the ceiling to actually start ripping and peeling back.  This was not a fresh leak. We opened up the ceiling and found saturated decking above that was actively leaking onto the ceiling.

Water Entry Point

We went to the roof and found the source of the leak on the deck above.  It wasn’t easy to find.  We had to pull back a layer of pavers  and disassemble the roofing system to get to the membrane. Once there we found a small tear. The concrete underneath it was soaked.  It must have gone unnoticed for months.

Why Membrane Quality Matters

There are many types of roof membranes available to builders.  Often a single-ply membranes are used to save money. Trouble is, single-ply is not durable enough handle the furniture, barbecues, planters, pavers and people that occupy the deck. Single-ply membranes, or worse, vinyl, tear or get holes.  It only takes a small hole, which is difficult to notice without testing, to cause a terrible roof leak.

We recently investigated leaks from several units in the same building. As you can see from this photo, a dropped key was enough to puncture the “protective” membrane and allow water ingress to damage the building structure and unit contents.  Sadly that was not the only puncture on this deck.

Residents want to enjoy their deck as much as possible.  Whether entertaining, lounging in the sun or gardening: People  want to get as much use out of the deck as possible and they place heavy things on it.  Barbecues, planters and furniture that is built to withstand windy days and harsh weather: all heavy items that get lots of use.


Drainage, sloping and waterproofing are vitally important to a deck because it also functions as a roof.  As we always say:  regular roof maintenance is the best way to keep all parts of the roof in the best shape possible including the decks.

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