Ah, summer! Those of you who just moved to Michigan from southerly climes probably weren't anticipating the Great Muggy. No, we don't import our weather from Alabama for June and July, this is all homemade stuff. Now you know why some of us like winter!
Of course, air conditioning makes it all much easier to take - if it goes on working. Now is a good time to go out and look at the condensing unit. The cottonwood fluff may be creating a blanket over your cooling coils, seriously reducing efficiency. Most of the time, this can be hosed off, but if you use anything else, it shouldn't be any stiffer than a paint brush. HVAC contractors have a special detergent for this and can blow the crud off from the inside of the housing, out through the coils, with compressed air. This is good to do every couple of years, but you can make a lot of difference with your hose.
And don't forget the filter. Yes, I know it's called a furnace filter, but your central A/C uses the same air handling and filtering equipment. So it still needs cleaning or changing,.
This month's main topic is a bit technical: Dirt Shrinks! Yup, that's it. What does it mean to you, the homeowner? Well, you'd be surprised...
In much of Southeast Michigan, the soil that supports our houses, streets, etc. contains a lot of clay. Clay expands and contracts with changing moisture content. Most of the time, rain and snow happen fairly regularly, and the expanding and shrinking are limited to the top few inches of soil, which doesn't affect most buildings. Every now and again, we get a few weeks without rain, and then things start moving.
The most serious drought in my memory was through May through August of 1988. We had a somewhat shorter one in '91, and another appears to be ending now. Not too may people noticed, but our local precipitation was way below normal from December of '99 till about 3 weeks ago.
As a dry spell lengthens past a few days, soil shrinkage extends down from the surface. After a dry month or two, buildings on shallow footings, such as sheds and porches start to move. Many of these structures are not really on footings at all, but merely on ratwalls, which go down about 2 feet into the soil. A proper footing goes down 42 inches, and that takes about a 3-month drought to start moving. In some of these cases the movement can be dramatic. There are thousands of homes with the main part of the house on a basement and a family room on a slab, and these family rooms can cause real trouble. Gaps open up in the brickwork, patio doors jam, floors start tilting. Just today, I looked at an older home in Grosse Pointe that had a 20-year old family room addition on a (presumably) 42-inch footing. The edge of the addition nearest the older part of the house had settled about 3/8 of an inch. At this point, the damage is limited to the brickwork, and can be repaired easily. If the movement continues, stress can occur on the roof, wiring and interior finish, and then something must be done to stabilize the footing.
The favored repair method is a process called deep-soil anchoring. Since the soil near the surface can't be trusted, big steel screws are driven into the ground next to the footing, going down as much as 20 feet to find a stratum that won't move. Steel brackets are then installed to connect these screws to the footings. If the building has no brick, it can often be lifted, back to the original position. If the walls are brick, there is a choice to be made: remove the brick, lift the structure and reinstall the brick, or be content to stop the movement where it is, and merely repoint the open joints. Neither process is cheap; a single anchor installation often runs about $1,200, and most settlement problems involve more than one.
The worst cases of soil shrinkage I have seen have been aggravated by trees. Yes, I hate to say it, because I never like giving anyone a reason to cut down a tree, but big trees near the house can be a real factor. A tree sucks considerable amounts of water out of the soil; it has to maintain a constant upward flow of water to the leaves to keep itself alive. If the roots are deep enough, this will affect nearby footings.
So, is there anything you can do to prevent this problem? It seems odd to advise homeowners to run water next to their foundations. A lot of time during home inspections is spent talking about ways to do just the opposite. However, unusual conditions call for unusual measures, so watering the soil next to the house is a good thing to do during a dry spell. (Of course, if you have a basement water problem, you should probably ignore this.) Your shrubs will love you for it. Shallow watering of big trees tends to bring their roots to the surface, so I advise using a device to get the water down further if the tree is bigger than 4 inches diameter. I use a Ross Root Feeder on all my trees. You can get one at the local garden center for less than $30. It connects to the end of the hose, and allows you to inject water and fertilizer as much as 16 inches into the soil. This doesn't have to be a frequent thing; I don't get out the root feeder until we have gone 2 weeks without a substantial rain. Most years, that only happens once or twice. How much water is enough? That's nearly impossible to say, and you may have to give it your best guess. If it's enough to keep the trees happy, it will probably keep the foundation from settling.
Time for the monthly nag. I already mentioned furnace filters, but when was the last time you checked the smoke alarms? I thought so. Come on, do it now before you forget. While you're at it, look at the pressure gage on the fire extinguisher. What, you don't have a fire extinguisher? Well....
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Enjoy the Summer!
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