A-1 ENGINEERING, LLC F-12583
      STRUCTURAL ENGINEERS    
                     San Antonio and Austin

Foundation Engineering,  

Foundation Surveys -  Frequently Asked Questions
Most of your questions on Foundation Surveys answered below. You can find more info on Foundation Elevation Surveys. Also, please visit your local homepage, Structural Engineers San Antonio and Structural Engineers Austin
Questions
What is a foundation survey?

If you are buying a new home or building a custom home, then you should have a foundation survey completed. A foundation survey is not a civil survey that you get if you are buying or selling a home. A foundation survey is a document that shows a schematic floor plan of your house with elevation readings throughout the floor plan. The elevation readings represent the high and low points of your foundation at the time the readings are taken. Consider it a snap shot of the current position of the foundation. The initial foundation survey is a base line of the contour of the foundation.

Why do I need a foundation survey?

If you are buying a new home or having a custom home built then the initial benefit of having a foundation survey is that the document becomes a recorded independent document that shows the elevation readings of your foundation at a point in time (date of measurement).  The document can later be referenced if you ever suspect the foundation may be moving or foundation related problems. If you suspect the foundation is moving, another foundation survey can be completed and the elevation readings can be compared to provide you (or structural engineer) with information on the degree of movement, location of movement and the relative rate of movement.  For example, you purchase your dream custom home tomorrow and today you had A-1 Engineering provide you with a foundation survey. The survey would show your floor plan with spot elevations throughout the floor plan. Three years from now we have a severe drought and you begin to see cracks throughout the building. Obviously you become concerned on whether you have foundation problems. Since you have a foundation survey taken today we can then re-measure the foundation three years from now and compare the differences in elevation readings to better understand the amount of movement and also determine where the movement is occurring. This information may lead you to possible plumbing leaks or movement caused by other sources such as trees, drains, irrigations systems, settlement or septic systems. This information becomes invaluable in deciding if you should have the foundation for your custom home “repaired” or leveled.

Who needs a foundation survey?

Any homeowner that is proactive in monitoring the performance of their foundation or a homeowner that recently purchased a home. Consider the following scenarios:

Scenario #1: One year ago you watched the construction of your custom built home and now you start to see cracks throughout one wing of the house. Just before the flooring material (carpet, tile, laminate flooring, etc.) was placed you had a foundation survey completed throughout the entire floor plan. Now that you suspect possible foundation movement you have another survey completed. The data between the first and latest survey are compared and the data indicates the corner of the master bedroom has dropped 1.25 inches. You call the builder and he says that his warranty coverage takes effect if the movement is more than 1.0 inch. If you had not taken the initial survey then the builder can claim that the foundation started 0.5 inches low; hence the builder is claiming that the foundation only moved 0.75 inches (1.25” – 0.5”) and the warranty will not cover the damages. Without your initial survey taken a year ago, you have no data to counter the builder’s assumption. However, since you proactively had a foundation survey completed, the data clearly shows that the difference in elevation between then and now is greater than the 1.0 inch criteria. Keep in mind that the one inch warranty clause is used in this scenario to illustrate a point and does not imply that all home builders have similar clauses or offer a warranty.

 

Scenario #2: You purchased your home five years ago now you see cracks within one of the walls of the main corridor.  You call a foundation repair company to give you a quote on possible foundation repairs. The four contractors that you call tell you that the foundation has dropped 2 inches across the front of the house as a result of the drought and this drop is what caused the damage. They recommend a foundation repair of press piles for the price of $10,0000 to bring the foundation back to where it started. You go to your file cabinet and pull out the foundation survey that was completed just before you first moved in. According to the survey the front wall was already 1.5 inches low when you first bought the house and it did not have all the cracks that are now showing up. Instead of agreeing on foundation repair you have another foundation survey completed and the data indicates the restroom near the corridor is 0.5 inches higher. Without the initial foundation survey the current elevation readings suggest a two inch drop but according to the data the foundation has only moved 0.5 inches (keep in mind that the foundation was already 1.5 inches low when you moved in). The higher elevation measurement in the restroom may have been caused by a plumbing leak. Relating the soil movement (damage to the wall) to the plumbing leak becomes a more viable reason to the movement (proven with historical data) as opposed to just accepting that “the drought” caused the damage.

 

Scenario #3: You purchased your home 15 years ago and this past summer you started seeing cracks at the edges and joints of your newly remodeled kitchen. Suspecting the worse, you call a foundation repair company to provide you with a cost estimate and recommendations for foundation repair press piles. The contractor states that you need 30 piers at a cost of $15k because your foundation has tilted and caused the damage. Again, you pull out the foundation survey that was completed 15 years ago from your file cabinet and get a current foundation survey. The data between the two surveys is compared and the data is relatively the same; suggesting the foundation has always been tilted and has moved very little. Since the foundation surveys do not suggest significant foundation movement you save the $15k in foundation repair and have the cracks assessed.

Are foundations constructed level?

Concrete contractors and custom home builders certainly try hard to construct a level foundation. The tile contractor and the framing contractor appreciate a foundation that is constructed level. However constructing a perfectly level foundation using common industry practices is not easily possible. As an analogy, consider the task of icing a square flat cake. The icing material may be pasty enough to get a smooth finish but because the icing knife is hard to control then the icing finish will have slight highs and lows. You may not be able to see the difference but they are there. That same phenomenon occurs with the construction of concrete foundations. Concrete foundations may have differences of ¾” to 1” inch from one side to the other (high or low) in the best of cases, a lot more for other home builders. Once the concrete foundation is constructed it is not feasible to remove it and start over. Having a foundation survey once the foundation is constructed will provide you with an orientation of where the highs and lows occur. This information is valuable in monitoring the performance of a foundation. Consider the foundation survey as a baseline of where your foundation starts.

I am buying a home, should I have the foundation completed before or after I move in?

If you are considering buying a home then we recommend getting a general (Level A) structural assessment after the home inspector has completed their inspection. The structural assessment should observe the roof framing as well as the overall building condition. Buying a home that has broken or over stressed roof members may cause cracks in the ceiling that may later be mistaken for foundation problems. The structural engineer should take some general elevation readings to get a general idea of the slopes of the foundation in relation to any visible cracks. His assessment should comment on the general levelness of the foundation. If you decide to buy the home then you should ask the structural engineer to complete a foundation survey of the whole house prior to moving in. This will allow the engineer more access to the entire house for more elevation readings. 

How often, after buying or building a home, should I get a foundation survey?

Obviously the first foundation survey should be completed prior to moving in, regardless if you buy a new home or have a custom home built. If you build a custom home, we recommend a foundation survey to be completed every three years after construction for the first 12 years and then as needed, unless you start seeing cracks, in which case, it may be once a year. This monitoring sequence allows the soils to go through 12 climatic seasons in between foundation surveys. The three year interval (12 climatic seasons) assumes the foundation will experience one very rainy year, one drought and one normal year. Problems with the performance of the foundation is more likely to be identified early.

If you are buying a home the sequence of monitoring the foundation performance is relative to the age of the foundation. If you buy fairly new custom built home (5 years or less) then the three year interval previously mentioned is suggested. If the home is older then we recommend consulting with a structural engineer to help you plan the sequence of foundation surveys to monitor the foundation performance. You may not need it at all, but most often at least one survey is recommended at the very least establish a baseline.

Regardless if you buy a new home or build a custom home, we recommend a foundation survey if you suspect foundation movement. Some cracks are misinterpreted as being caused by foundation movement and homeowners are convinced to “repair” a foundation that has moved very little (performing relatively well). The foundation survey for new home buyers is the most valuable document to monitor and detect possible foundation problems.

What would Confucius say about a foundation survey?

 

“It is better to have the information and not need it, then need the information and not have it”.

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If you need a foundation survey, request the Level A+ structural report, please read our page Foundation Inspection