By Mitch Kuffa
Let’s talk about Freezing, Thawing, and FROST:
Most people do not understand the negative impact that frost has on many construction materials. Houses that are built in northern climates are different than houses that never experience freezing or frost impact. The dictionary defines frost as “The atmosphere condition when the temperature is below the freezing point of water or the process of freezing”.
In construction, we commonly refer to frost as it relates to ground water freezing in the earth (which makes construction techniques more difficult). It is my personal opinion, that the area in which we live is extremely sensitive to frost and its impact on other items. Our temperature range here is such that we get week after week of temperature changes that go below freezing at night and thaw during the day. In addition, we are surrounded by the great lakes and typically have a lot of water around us. When water freezes and thaws in the ground we get an expansion and contraction scenario that can be detrimental to construction products and building. Rigid construction materials are the most sensitive to “frost”. Brick, masonry block, concrete, ceramic tile, etc.
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Now, take a rigid construction material that absorbs water and then fluctuate the temperature above and below freezing, time after time, get this expansion and contraction factor AND WHAT HAPPENS? The rigid construction material cracks, breaks, shales or fails. Also, keep in mind that horizontal surfaces are more prone to this type of problem. Water will run off a roof or down a brick wall, but sits and saturates the top of the chimney, brick or stone window sills, the top of masonry fences, driveways, etc.. That is why these areas are impacted more often. Chimneys always seem to deteriorate at the top and then the condition lessens as you descend down the chimney height.
Foundations need to be placed in the ground to a level deeper than the anticipated ground waters ability to freeze. We call this the “frost line”. If the water freezes deeper than the depth of the foundation or the “frost line”, it will heave or crack the structure. This is why you often see porches on older houses that are settled, cracked, crooked or falling apart. The previously required shallow footings were not deep enough and allowed the frost to penetrate beneath. Then when the ground thaws, contraction takes place and the rigid construction material moves again. This back and forth motion, over a long period of time, deteriorates the strongest product.
Frost can also be driven down by vibration. This is why on the coldest winter days as you’re watching the news, they report a major waterline freeze-up, under some major intersection that has burst and is shooting water all over. It typically happens where there is a lot of vibration from above such as trucks, vehicles, etc.
Several years ago we were installing a footing for an addition and were happy to find that even though it was cold outside, the ground was still soft for digging. As we progressed and came close to the house we found that the ground suddenly became very frozen and almost impenetrable. We could not understand why the ground changed until the owner let her 2 sheepdogs out and they ran back and forth over that area trying to get into the residence. The weight of their bodies prancing on the earth drove the frost down.
During very cold months we have what is called “frost laws” that go into effect. These laws prohibit trucks over a certain weight from driving on specified streets. The reason for this is that once the ground freezes beneath the rigid concrete roads, they become more sensitive to heavy loads and the vibration of those vehicles. Even the strongest, thickest, more re-enforced and sophisticated highways are impacted by this condition (such as our freeways). This is why there is so much road construction in this area. If we go further north, the ground freezes and stays frozen. If we go further south the ground seldom freezes and therefore does not impact the roads.
So now that you have some understanding, go check the top of your chimney (from the ground with binoculars), put a clear masonry sealer on your brick window sills or top of your brick fences, clean your gutters to discharge away from the house and foundation, seal the cracks in your driveway and insulate yourself from the negative impacts of frost on your living environment.
Inspections By MJK