Leaks, in general
What is a leak? Obviously, it’s water where you don't want it. Simple, but not particularly useful when what you’re really interested in is choosing a robust wall assembly, drawing a successful detail, or trying to diagnose and repair a leak that’s already occurred. It will help us to take a more disciplined approach.
A leak requires (yes, requires):
1. A source of water
2. A pathway for that water to travel
3. A driving force pushing water along the pathway
4. Something for that water to damage
Note that for there to be a leak, ALL of these factors must be at play, not just one. This is hard for some people, mostly because we spend so much time obsessing over sealing pathways in our buildings that it seems pretty close to blasphemy to state that not all holes produce leaks. But there you have it: just because you have a hole doesn’t mean you have a leak. In fact, our buildings have thousands of holes, sometimes TENS of thousands of holes and we’re usually not terribly concerned because either not enough water reaches those holes, there isn’t enough of a driving force pushing water through the holes, nothing gets damaged as a result, or some combination of the three.
Now, to be clear, I’m not suggesting that this gives anyone license for inattentive design or sloppy construction, or that just because we don’t see damage occurring (rot, mold) that it’s not important. What I am saying is that we ought to be smart about the holes that we design (windows, doors, service penetrations, fasteners) and about those we don’t design but we prepare for nonetheless (construction defects) and being smart means recognizing that we have more than one tool available to us.
Next: But really now, what about that fastener?
A leak requires (yes, requires):
1. A source of water
2. A pathway for that water to travel
3. A driving force pushing water along the pathway
4. Something for that water to damage
Note that for there to be a leak, ALL of these factors must be at play, not just one. This is hard for some people, mostly because we spend so much time obsessing over sealing pathways in our buildings that it seems pretty close to blasphemy to state that not all holes produce leaks. But there you have it: just because you have a hole doesn’t mean you have a leak. In fact, our buildings have thousands of holes, sometimes TENS of thousands of holes and we’re usually not terribly concerned because either not enough water reaches those holes, there isn’t enough of a driving force pushing water through the holes, nothing gets damaged as a result, or some combination of the three.
Now, to be clear, I’m not suggesting that this gives anyone license for inattentive design or sloppy construction, or that just because we don’t see damage occurring (rot, mold) that it’s not important. What I am saying is that we ought to be smart about the holes that we design (windows, doors, service penetrations, fasteners) and about those we don’t design but we prepare for nonetheless (construction defects) and being smart means recognizing that we have more than one tool available to us.
Next: But really now, what about that fastener?