Foundation-insulation inside or out

The question has been asked is it better insulating the inside or the outside of a concrete wall?
First we’ll look at insulation on the inside wall only. The inside wall has studs 16″ on center with insulation keeping the cold out and the warm air in.

1. You have brought the cool weather into the foundation;
Let me explain; If you have a block, or clay tile wall system air inside block is chilled the cold air drops to the footing no big deal if you live in Nevada to Virginia.

But if you live in New York – Idaho and North we have problems. The cold out side is so cold that it can freeze the footings of the house.

With a poured foundation it takes longer but can still happen.

Freezing the footing is not a problem, the problem comes in when the ground around the footing freezes, now we have a making of a disaster. 90% of the time there is groundwater next to the outside edge of the footing in some cases I’ve seen footings and basement floors sitting in water.

When adding a cold winter to this mix and the ground water freezes around the footing, the water has to expand 10% when it turns to ice, on the inside of the structure is forces the water in to the cement slab and sometimes through the slab on to the floor above.

But the water under the footing has no place to go, so it lifts the house (heaving it) and not evenly breaking the concrete wall cracking sheetrock, plaster, and stucco right up to the roofline.

I’ve seen a shift in trusses like a bulge on a roof, magnifying the problem as it lifts the structure up.

2. Water – IE moisture loves to migrate into concrete. We have seen a commercial building that is a warehouse. When it was built they excavated a sump and filled it with sand compacted it and than built on it.

Now 5-10 years later the concrete walls are flaking paint, and chips of concrete pop off up to 24′ of the wall. What’s happening? The high water table is back in the ground, water can migrate through concrete vertically 28′ from the source of the water.

Remember nature’s rule-water must be allowed to expand, and if it cannot, it will move what ever is in its way to expand 10%.

Know this if you don’t remove the moisture (water) from the footings it will remove paint off of concrete and have popping chips of concrete.

If there is water against your foundation wall when it freezes it will blow the face off the concrete and in a few years there will be major holes in your foundation not only letting more water in but also exotic organisms and creating a mold problem in the structure.

  • Same house and same problems water is present around the footing. This time lets insulate the outside of the wall. What has changed the temperature of the footing it now has no way of freezing therefore it cannot heave.

    I’ve seen numbers of basements with white wavy lines looking like salt on the concrete walls people ask what is it? When this occurs it means 2 things;

    The ground around and under your house is a PH level of (base vs. acid) which is good for some types of vegetation.

    The PH level must be checked for example 1. Battery acid, 2 Lemon juice, 3 Vinegar, 1-5 range acid rain, 6 Milk, 7 -neutral, 6-8 range stream water, 8 Baking soda & sea water, 10 Milk of Magnesia, common name for the chemical compound magnesium hydroxide, Mg(OH ) . The viscous, white, mildly alkaline mixture that is used medicinally as an antacid and laxative is a suspension of approximately 8% magnesium hydroxide in water. 12 Ammonia, Where does ammonia come from? Ponds lakes any type of organic matter (including live animals and live rock), ammonia will result. 13 Lye Where does Lye come from? 1 natural source of lye is ashes of burnt wood.

    This also shows that you have water on the other side of the wall and it is using the inside surface of your basement to evaporate itself into your house with the gases and or other types of chemicals. An average basement of 1000SF can evaporate 50 Gallons of water per day then add water behind the concrete walls of 868 SF. another 43 Gallons of water is trying to migrate into your house making your humidity level in the basement extremely high. This is why your basement smells bad; it’s not your or any to do with your cleaning efforts.

    This water is helping with the growth of mold in your house as well as frost on your windows in the wintertime and to high of humidity in your house, making smell musty.

    This water is helping with the growth of mold in your house as well as frost on your windows in the wintertime and to high of humidity in your house, making smell musty.

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