A Monticello, Minn., woman appeared on local television news recently, worried about a $92 water bill and wondered if her house was slowly descending into a sinkhole.  We at J&W Asphalt don’t know what’s causing her increased water bill, but we do know what’s going on in her driveway.

It’s called a sunken apron

It has to do with the way buildings are built. When a builder begins work on a house, for example, he excavates a hole for the basement. When the basement is finished, the builder replaces the dirt around the basement exterior. As the dirt is piled up, spaces or air pockets are left in the piles. As the years go by, rain and snow do their work, the dirt slowly compacts, and the house settles. This process usually takes about 10 years.

Many older homes were built on a cinder block foundation. Cinder blocks are shaped like the Roman numeral III, with hollow spaces between the Is. When builders build a garage, they frequently place half of the outer edge of the garage floor on the cinder blocks and the remaining half protrudes out the door. They cover it up with a concrete cap. If the builder didn’t compact the earth thoroughly, it can be a recipe for trouble.

Over time, the freeze/thaw cycle that’s so typical of a Minnesota winter does its work. Water and salt drip from your car. Salt is a notorious eater of concrete. The concrete is slowly chewed away and the cinder blocks at the seam where the driveway and garage floor meet are exposed. Suddenly, it looks as if your driveway has pulled away from the garage and there’s a hole underneath your house that reaches toward China.

Infrared repair can fix driveway holes

J&W Asphalt has an easy fix for this problem. It’s called infrared repair. We heat up the existing asphalt with infrared heat. This softens the asphalt. As it becomes more pliable we add gravel and more asphalt and push it into the hole. We keep doing this until the driveway is level again. The infrared heat leaves no seams behind. Your driveway looks new and whole again. Infrared repair costs about one-third of the cost of re-doing a driveway. It’s definitely a cost-effective process.

When we replace a driveway, we’ll mix concrete and put a new cap over the cinder block. When a driveway is 20-30 years old, it’s already settled. When we put down a new asphalt surface, it won’t sink, and water will run easily off the top.