what does your garbage do for you?

[yogi]

There are a few factors to be considered when measuring ground temperature, none of which I took into consideration when I made my off the wall comment. Folks who take this a lot more seriously and have studied it have a pretty good idea of what is really going on. In the linked article I'm looking at Figure 3 which depicts the change in ground temperature as a function of depth. At 8 feet down, which is where most basement floors are located, the change is +/- 10 degrees F. So, if we took the 55 degree average of which you speak (the mean is actually 52 in the St Louis area) that says the mid 40's is where the basement floor will sit during the winter. Of course, the further up the wall you go, the closer you will get to the air temperature. Considering the gradient of temperatures, the average for all the concrete may be considerably less than the 42F I quoted. Now, at 30 feet down where all those caves are located the chart shows no variation in amplitude. Mid to upper 50's it is down there.


BRRRRR http://www.builditsolar.com/Projects/Co ... atures.htm

[Kellemora]

Hi Yogi

The only chart relevant on that page is Figure 3 that looks like a series of Vs, which you pointed out.
But I don't think you understand exactly what they are showing on the graph.
This is an amplitude graph and requires a time factor.
The longer an area stays at perhaps 0 degrees, the deeper the frost line will become, until it reaches balance with internal earth temperature.

St. Louis often gets down to 3 or 4 degrees below zero.
Based on that chart, the temperature would be 0 degrees at 20 feet down.
Yet we know the official frost line depth is only 30 inches down.
Which means the ground does not freeze below 30 inches.

At 8 inches below grade, the coldest temperature ever recorded in Missouri was 28 degrees, once in 1982 and again in 1996.
At 20 inches below grade, the coldest ever recorded was 35 degrees, in 1996.
And at 40 inches below grade, the coldest was 42 degrees, in 1978

Way back in 1905, the town of Warsaw, Missouri broke the record at -40 degrees.
Since then, the coldest St. Louis has ever seen was -16 degrees in 1989.

1978, 1982, and 1996 each saw -10 degrees for over a week, which is why those dates were used as measurements for the coldest below ground temperatures ever recorded.

Jumping to Denver, the official frost line is only 36 inches down, but in Vail it is 38 inches with 40 inches being code for plumbing installations.
Denver is also where they often insulate the top 1/3 of basement foundation walls. This is to prevent frost buildup on the foundation walls, more so than for keeping heat in the basement. If you want to heat the basement, then the whole of exterior walls should insulated.

[yogi]

Figure 3 graphs the variation from the median ground temperature. The variation decreases with depth. At ground zero the temperature varies proportionally with the air temperature, but at 6' down it varies only by +/- 10 degrees. The median temperature also is a function of depth. At 28 feet below the surface there is no significant variation, and it is figure 2 that shows what the median is across the United States. It's a dynamic situation that does factor time into the calculations. One thing for certain is that at a depth of 6' in and around the St Louis area the ground temperature is not stable six feet under. It varies by 20 degrees.

How the median temperature is measured doesn't change the fact that my concrete basement wall temperature is a hella lot different than the air temperatures outside. I suppose moisture condensation would be a consideration when insulating concrete basement walls, but in the thirty years at my old (and colder) address up north I've never seen moisture from condensation on my unfinished basement walls. They typically are colder than the ambient air, but apparently never below the dew point. The house I'm in now has one half the basement under ground and the other half at ground level. The air temperature in this basement is not stable over time and that is due to the wall that is not concrete nor encased in 6' of cold earth.

[Kellemora]

All of the homes, other than this one in which I have lived, had full basements.
I really miss having a full basement, which is why I dug out a good portion of the crawl space.

We had humidifiers in our furnace duct work to keep the humidity up.
Dad kept both of his houses cranked up a little higher than I did, and on the top 1 foot of an unheated room in his second house basement, he would get some frost, most often around and near a basement window, and on the window itself of course.

One house I lived in had a separate basement section under the front porch, used for food storage. Took the place of a root cellar I suppose, back when the house was built. This was the only area of the basement where the walls would collect moisture, but they never got frost on them like at dad's second house. This only happened when the outdoor temp got below 10 and stayed there for a long time.

I do know the further north you go, besides the frost line being further below grade, the underground temps are cooler, probably because of the longer duration of the cold season. What's the frost line in Siberia? I think it is about 1,500 feet down, hi hi...

[yogi]

I don't know what's going on in Siberia, but I believe they have hot springs embedded in the ice over in Greenland. I kind of doubt they have basements though. It's must be impossible to excavate anything in permafrost.

[Kellemora]

My late wife's sister used to live in one of the northern New England states. I was never sure if she lived in the north tip of New Hampshire or Vermont. She worked in Maine, and her husband in Vermont.

The basements there had ten foot ceilings, because the foundation footer had to be down at 8 foot below grade to prevent frost heave. Add the two feet above grade for basement windows and they all had ten foot ceilings in their basements, if they had basements.
She never mentioned what type of insulation if any was in the basement, but theirs was a finished basement when they bought the home.

Many homes only have a crawl space under them, but from snippets of info I gleaned, they all have piers going down to 8 feet, even if the walls only go down two or three feet. I don't suppose they could have slab homes there?

[yogi]

Thirty some years ago I built my house in a suburb of Chicago. It was a simple ranch style that measured 30x50 feet. The basement had 8 foot high walls which were 8" or 10 " thick. I'm not sure what the code was back then. Anyway, those walls alone cost me $15,000 - and that was thirty years ago. Ten foot walls or even piers have got to be unbelievably expensive these days. I don't think I'd miss a basement if I had a big enough garage and attic. Apparently manufactured wood and plastic walls are cheaper than concrete.

[Kellemora]

Be glad you don't live down south here.
When I got ready to install my driveway, I bought the welded wire grid, dug it out, set-up the forms, added the base gravel, then called the concrete company.
I knew what it would cost back home in St. Louis County as I did a lot of flatwork.
About had a heart attack when I learned what they charged per yard of concrete down here.
One section would cost a more than an entire driveway back home.
I was looking at like 8,000 dollars to do the driveway.
Called a blacktop company, and with a little luck I got it for 2/3 off their quoted price, due to a job cancellation.
Two layers, first layer coarse and rolled, second layer fine topping and rolled.
1200 bucks total. The quote was for like 3500 bucks. Plus I sold all the welded wire fabric sheets for only 20 bucks less than I paid for them, and the buyer picked them up.

I poured four shallow piers for a deck, mixing myself, and it still cost me about 80 bucks per pier, counting the sonoduct tube forms.
I think I could have bought fiberglass resin cheaper, hi hi...