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Moisture Problems – High Water Table Signs (Part 10)

When a home is built on land with a high water table, re-grading and gutters are not the correction to the problem. Remember, grading and gutters correct stained, damp or wet walls and, sometimes, minor floor seepage stains. This problem could exist on a portion of one wall, on an entire wall, or on all the walls. It will depend upon the condition of the outside landscaping on the other side of the foundation. Has the house not spoken to you? Are you now confident in being able to recognize these types of situations?

In a high water table situation the observations will be very different. For example, you might spot that the bottom of wood beam posts in the middle of the basement are soft and rotted. Maybe sections of the concrete floor are cracked, buckled, and pushed up from hydrostatic water pressure. Typically these cracks will have water marks on the edges. You might even see loose vinyl floor tiles, tiles with water marks on the seams, or a brittle crackly noise when you walk on these tiles. If you’re really adventurous, take a small screw driver and pull back carpet corners looking for water damaged wood tack stripping. Can you see a consistent water mark ring on all the walls around the perimeter of the foundation?

If you can see any of these clues, can you begin to
hear the sound of a flooded basement?

Flooded basements will have the same problems existing on all four walls and over the entire basement floor. The subsurface ground water is coming up into the basement. It is not surface water coming down the sidewalls. There is only one way to correct this situation…install a sump pump and foundation drainage tile.

Do these systems really work? Are they always reliable?
Do they indicate a problem home?

Great questions, next time let’s ask the house.

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Moisture Problems – High Water Table Issues(Part 7)

Last week I asked why roof gutters with no or short downspout extensions was so bad. The answer is, when dumping massive amounts of water on small isolated points of a foundation, even the best of soils and grading cannot handle the volume. Notice on this picture the mold and water damage going up the corner of the basement. This is where a downspout had been missing on the outside of the house. Gutters are good, but if not kept intact, they can also funnel water into a basement or crawl space.

DO YOU REMEMBER?
90% of wet basements are caused by not controlling surface water

Control of surface water is accomplished with positive landscaping, hardscaping, and sometimes gutters. But control of sub surface water can be a little more difficult…to recognize and to correct. Less than 10% of the time homes are built on land with a high water table. In these situations landscaping, hardscaping, and gutters will do nothing to keep water out of the basement. When a home is built in a water table or so close to a high water table that fluctuates with heavy rains and snow thaws, you will need to have a sump pump and drain tiles.

How can real estate agents and homeowners tell if a home is built on a high water table?

In this situation, basements and crawl spaces will flood. What I mean is the entire basement floor will get wet… not just damp walls and maybe some seepage stains along the edges of the floor. Flooded floors disclose themselves almost like leaving a dirt ring around your bathtub when you get out. There will be uniform water marks on all four walls at the same elevation off the floor.

There are other indicators of a high water table problem and we will cover those as we continue our journey with basement and crawl space moisture next week.

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Moisture Problems – the Basement (Part 2)

We will launch our tour together in the basement or crawl space seeking moisture, figuring out its source, and providing solutions to the problem. The most common dampness in below grade foundations originates from outside the building. Moisture intrusion is caused by inadequate control of surface and ground waters. The results can be discolored walls, seepage on the floor around the perimeter of the foundation, or a completely flooded basement.

So what causes these conditions?

The most common cause of basement moisture is improper landscaping. Simply put the earth grading is sloped towards the foundation. This is called negative slope. The first step in managing surface water is to make sure the earth slopes away, positive slope, from the foundation on all sides of the building. Even the smallest depressions or settlement of soil can trap water allowing it to dampen the walls and stain the foundation.

Although type of soil can have an impact on whether surface water will enter the building, there are 3 common grading defects that should always be corrected. They are:

1. Flat or negative slope
2. Settled backfill
3. No drainage swale

So we see that landscaping is always a problem, but is that the only thing on the outside of the home that causes moisture intrusion?  Check back soon for part 3 in our home moisture problem resolution series!

Doug & Julie Hastings
Your House Whisperers
Residential & Commercial Home Inspectors

 

 

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