Wednesday, April 9, 2014

The Importance of Elevations Studies.

The other day I was meeting with a customer, and getting everything set up when he asked me "What's that yellow box for?"  When I told him about shooting elevations, and how we would compare the elevations to the distress and the frame level he said "You're the 4th one out here, and nobody else has used anything like that." An elevation study is very important for diagnosing and evaluating slab performance.  I'll explain why below.

1) Reflects overall slab elevations.
I am a big fan of the 4 foot level.  I use it quite a bit on almost every house that I look at.  It's a very important tool in the evaluation of slab performance, and should not be discredited.  But using it as the ONLY tool?  Think about what a level does.  It shows if the surface is uneven or not.  But does it tell you how much it's off?  Does it tell you if one end is high or one end is low? Will it tell you settlement vs. upheaval?  A four foot level can tell you none of these things.  Look at the examples below.

These three elevation studies tell me three completely different things.  The distress on all three homes was similar on the outside, but there are three very different reasons and causes for movement.  The first was determined to be settlement along the front, caused by large trees.  The second, was mostly dropping in the middle due to a plumbing leak, and the third was determined by the engineer of record to be tilt (within Tilt Standards).  The one on the left needed only exterior remediation, the second needed only interior, and the third actually needed no work at all.  The key to elevations is they can be evaluated.  The can be recorded, and they can be compared.  None of that is generally done with a 4 foot level.

2) Elevation Studies can be re-recorded, and compared.

Scenario #2......I had a couple buying their first home in March of 2013.  There was minor distress along the right side of their home, but no structural damage inside the home.  Tile flooring showed no cracks, all doors aligned perfectly, windows operated as intended, but there was a few hairline cracks in the drywall on the interior.  I told them the home had seen some minor movement in it's 30 year life, but it was nothing to be concerned about.  They needed to watch the large trees in the front, make sure they were properly watered, and should watch the drainage in the back as there were areas for rain to collect and pond.  A little over a year later, the couple called me back.  Their tile had "tented" and there were some new cracks forming in the back corner of the master bedroom.  I went back and recorded another elevation study, and compared it to the original one.  That Elevation Study is the one to the left. Upon comparing, you can see roughly a 1/2" change in the back right, while the others along the front are virtually identical (within 0.2").  It was determined that the drainage issue mentioned before (which was also never addressed) was the culprit for the movement.  That the water accumulation was also the culprit for their tile problem, and that no piers were needed.

Two other companies had also evaluated this home. One, using a four foot level, recommended over 25 piers around the front of the home, and back left corner (but did not address the movement notated by cracks in the back right) and the second recommended 39 piers around the entire home. The second evaluator used no tools or equipment at all, but only did an outside visual inspection.

3) Post Work Elevations
To me, post repair elevations are just as important as pre-work elevations.  Why? Because then we know two things.  1) How much we lifted it     2) Where the elevations where when the lift was completed.  Final elevations in our company are kept, so if there is an issue in the future we can determine where that issue is coming from.  Elevations can be recorded, and compared, so we can see if our repairs are experiencing an issue and need to be warranted, or if a new issue has risen since we were there last.  This gives information over slab performance, and protects our customers against the "Well if it's still movin' it just needs more piers!" scenario.  Post work elevations are as much about buyer protection as the are against company protection.  It's a two way street.

Once again, if you have any questions over the performance of your slab, please don't hesitate to contact us.

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Let us know if we can help you in any way, if that is to aid you with a foundation repair, provide a competitive estimate for repairs, or to help you evaluate and diagnose your foundation performance.

Thanks for Reading,

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