An Ounce of Prevention is Worth 34'000 Pounds of Cure

I thought long and hard about what would be the topic for this entry. I've encountered a few things since I last talked to you and many have been considered. But when I encountered the situation I'm going to describe to you, the choice was clear that this had to be shared. The reason is because this prevalent problem can be prevented so very easily and yet, after the fact, will be so expensive to fix. The ultimate “stitch in time saves nine”, “ounce of prevention saves a pound of cure” or whatever colloquialism suits your fancy that basically describes the monumental error of pouring a driveway the completely wrong way.


Concrete driveways are many and varied. Different colours, strengths, thicknesses, pitches, patterns etc. But what is shared between all concrete pours is a need for movement. Concrete needs room to expand and contract with the changing climate. Even a person with no interest or experience with concrete has most likely walked down a sidewalk and noticed the lines running perpendicularly through the sidewalk at very regular intervals. There are two types of joints here. One is a control joint. A joint that does not separate two sections of concrete but creates the weakest point in the slab and thus, where the slab will inevitably crack. Keeping the crack neat and tidy. The second is a complete separation of slabs that goes all the way through. These joints, called expansion joints, usually have an asphalt soaked fiber material (or recycled rubber) in them to fill the gap and allow the two adjacent sides to move independently as needed. These are invaluable and should be found about every ten feet.


Today's example is not a sidewalk, it's a driveway. But the principles are exactly the same. So what does every driveway need? Room for expansion, contraction and movement with the climate. So let's take a look at one. The driveway pictured was poured tight between two large buildings. With no expansion joint separating the driveway from these buildings. Can a driveway possibly move in between these anchors points that are much more firmly planted? Well the answer is yes. Sorry that is sort of a trick question. But the problem is that it can't possibly move in the way we would like. Which leads us to the cracking. When it rains, water pools against the building at the driveway edge, soaking underneath and collecting there. When the water freezes it heaves the slab up. The only problem is that the slab is anchored to the sides of a sturdy building. So the slab heaves in the center, but not at the edges. Resulting in the badly cracked, crowned slab we see here and water damage to the sides of the buildings too. With the driveway higher in the center than the edges, the water is encouraged to flow up against the side of the buildings, over the joint that allowed it underneath in the first place and further exacerbates the problem. The only solution at this point is to remove all this failed concrete and pour it the right way. A very costly mistake that could have been prevented with a slight design change.


How should this driveway have been poured? Not up against the buildings! And with not even a HINT of pitch towards those buildings. Here's how I would have done it. I would have placed a trench drain (pictured above)right in the center of the driveway and then poured on each side of it with a 2% slope UP to the buildings. This way, any water on the driveway will be directed to the center of the driveway to a drain instead of up against buildings. I would have also placed expansion joint material between the buildings and the driveway to facilitate movement. This joint can be sealed over with a quality caulk to further protect the building from water seeping through that joint. But with our proper pitch, this is less critical. This drain exit can be connected to a storm drain, bubbler or run to low ground with erosion protection. Problem solved. Had this been done at the time of construction there would be no problem. But now this driveway has 34'000 pounds of failed concrete (8.5c.y.)that needs to come out and be repoured the right way. There is no easy or cost effective way to correct this problem. The concrete will not settle back down to a proper pitch and sealing the cracks will not eliminate the water sitting at the sides of the building.


The moral of the story? Spend a little more up front and save yourself a ton of headaches, property damage and cost down the road. It's not worth cutting corners to save a few bucks because it will always come back around to bite you. You can pay a little more now, or a lot more later. Consult reputable professionals who know what they're talking about and listen to their advice. Get multiple opinions and compare the responses. Ask contractors about things the others have told you. Guage the responses. And of course, do some research yourself to at least somewhat familiarise yourself with the project in question. You wouldn't go buy a car without knowing how to drive right? Well don't get major projects done on your house if you don't know at least a few basics from the outset.  

Posted on March 24, 2015 .