The primary definition of fail-safe, according to Merriam-Webster, is “incorporating some feature for automatically counteracting the effect of an anticipated possible source of failure.”
In a previous article accompanied by video (“Belts, Suspenders, and Bulk Water” – read/watch it here), I discussed taking extra precautions to exclude the entry of liquid water into an enclosure. Again, “belts and suspenders” means extra – like if you wear both.
Which I don’t.
The order of priority in the building science knowledge realm is to first manage bulk water, then air, then vapor, and then thermal concerns. This is not Dr. Lee’s law. This is building science logic according to Dr. Joe Lstiburek, the dean of building science.
The premise is that you really shouldn’t worry about air intrusion if you can’t keep water out of your enclosure.
A corollary would be, if you do a good job with water and then air, vapor and thermal concerns will all but take care of themselves. Meaning that there will be very little, if any, additional work to perform.
Back to bulk water. It sucks having it where you don’t want it in your house. Like when it’s not contained in a bathtub. Or a drinking vessel.
The forces acting on and from water, actually, are among the strongest natural forces known to humans.
Proving that statement is beyond the scope of this article, but if you have doubt, consider that:
- Mere inches of moving water can knock you off of your feet
- The hydrostatic pressure of a sewer line backup can lift an entire concrete slab (at a weight of 50 pounds per square foot at 4 inches of thickness)
- The pressure exerted by water freezing underneath ANYTHING (remember than the volume of frozen water is greater than the volume of an equivalent number of molecules of liquid water) will heave and lift ANYTHING off of its resting place.
OK, forget about forces for a moment; consider sanitation –
- Water carries bacteria and other undesirables
- Water makes reproduction of mold spores possible
- Water is wet. Wet is gross.
Now do you understand why it’s important to keep unwanted water away?
In my previous bulk water manifesto, I didn’t do much of a deep dive other than talk about the junction between a wall and a foundation wall.
Now deep into my own project, there are certainly more items to discuss.
- The building code requires that a house have an exterior foundation drain (done)
- The building code does not require that a house have interior foundation drains or “laterals” as they are called, to take bulk groundwater away from underneath of the finished slab of the lowest level (belt and suspenders – done.)
- I noticed that the excavator ran the laterals to daylight – the ditch. What if the ditch filled with water?
Fail-safe #1: The furthest (highest) extent of lateral at the furthest point from which it drains from the house – I connected it to another drain in case the lateral filled with water than had no where to go if the ditch filled up. I installed an interior storm water sump to collect this water. And a pump to pump it away.
Fail-safe #2: As described in my accompanying video, the finished floor level of the living space of the lowest level is 2 inches lower than the finished floor level of the mechanical room which is under the garage. (There are many structural reasons for this, and this eventuality was unavoidable.) Mechanical rooms have tanks that hold water. A failure of a tank could mean a flood downstream in my living space.
Not so fast.
I installed 3, 4-foot sections of trench drain to collect this potential flood water (including one section immediately in front of the door that divides mechanical room and living space) and drain it into the storm sump, then redistribute it via a pump outdoors at whatever elevation I choose. Pumps can pump high, and then water can flow downhill without any further input of energy.
- Fail-safe #3: I placed a perforated drain tile underneath the finished slab at an even lower level to first collect groundwater before it would even reach the laterals in that location. This, too, is collected in the storm sump and pumped away.
I suppose that I could have cut any of the corners described above. The building code did not require me to perform any of it. It was all extra, on my nickel. (If only construction work were measured in nickels).
But I guarantee that I’ll be able to sleep at night. And carpet my floors. And not worry about the next 100-year rain.
As you think about that, consider whether what most would call “overkill” is really an inexpensive insurance policy that requires no monthly premiums.
Click here to watch my video.
Until next time,
Dr. Lee Newton
How A Doctor Learned To Develop Real Estate