I spent several childhood years living with my parents and sister in my grandmother’s house. The floors all over the house were wood, and they were kept waxed and polished and just slippery enough so a mid-sized cat could mimic a hockey puck.
My sister had a cat named Tiger. I found that if I ran through the kitchen past the cat’s favorite sleeping place dragging a rubber mouse tied to a piece of string, the cat would awake, jump up and chase the mouse. I would lead the chase through the den, down the hall and across the living room, where I would jerk the mouse onto the small rug by the front door as I took a sharp right turn into the front bedroom. (I was barefooted for better traction). The cat would see the mouse on the rug and without breaking stride, pounce full speed to make the capture. As soon as the cat’s weighted momentum made contact, the rug would absorb all of the inertia and, unhindered by friction (remember the highly polished floor?) skid the remaining few feet and slam the full force of the cat’s mass into the front door, finally coming to rest in a heap of carpet folds and cat fur. There was a moment when all was silent and motionless. Then, Tiger would slowly crawl out of the heap making no attempt to hide his embarrassment, while I stood grinning ear to ear and thinking “……..Every time”.
The piece of that story I want you to remember is the folded rug. The door wouldn’t move, so the rug absorbed the shock by folding.
Here’s what started this whole topic. I saw a tile terrace located between a house and a massive, masonry garden wall. The tile was badly buckled, sort of folded like that rug with the cat on it. At the base of the brick wall, at each corner where the terrace met the house, were two wide cracks rising from the tile up the brick wall about sixteen inches. At first glance it appeared to be a foundation failure. But expansion was the culprit.
The tile had been placed directly against the brick wall of the house on one side, and the garden wall on the other. When summer temperatures soared to unseasonable highs, the tile expanded pushing against both the house and the garden wall. The garden wall was massive. It didn’t move at all, so the expansion pressure shifted toward the house. Brick is very strong vertically, but has less strength from side to side. That’s because brick walls on most houses are hollow. The brick cracked exactly at the points where pressure was applied by the expanding tile. Eventually the brick had moved as far as it could against the structure of the house. Trapped between the house and the garden wall, the still expanding tile began to buckle on itself.
Only one thing was needed to avoid this problem — room to expand. There’s a construction thing called an expansion joint. It’s nothing more than a gap that puts space between a material that will expand, and a material that won’t. If such a gap had been built-in with that tile terrace, it could have expanded as much as it needed without ever coming into contact with the house or the garden wall.
Other materials will behave in similar fashion. If wood or vinyl or tile are installed when it’s too cold or too dry, they will be in a contracted state. Then, as temperatures and humidity rise, those materials will begin to expand. If no room has been allowed, pressure will be forced against whatever is beside the material. Brick will break, wood floors will dome up, vinyl will ripple, tile will buckle and cat-rugs will fold…………..every time.
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