Monday, March 10, 2014

The importance of aligning your foundation, and your foundation repair.

These last few weeks I have looked at a number of repair plans given to home owners and started to realize that there is a definite need for this post.  This sounds so simple, but it is so often over looked.  When dealing with a major repair (or especially with internal piers), it is vital that your repair plan aligns with your foundation.  There are many out there who are doing this wrong, and there can be consequences.

To start, lets get in to foundation design.  Now if you are one of the lucky ones who happens to actually have your foundation design, this is a very simple process.  If you don't, there are some tricks to find the actual layout.  To begin, we will start with slab on grade foundations.

Foundations are designed in a grid pattern of beams, with a small slab laying on top of them.  This design is why they are called "Floating Slabs". The depth and width of these beams varies.  Usually, beams are somewhere between 24-30 inches deep, and 12-18 inches wide.  Some custom homes will have much larger (I've seen beams as deep as 6 feet.) and some homes will have no beams, or beams that are extremely small (I've seen as little as 4" deep and 4" wide) across the interior.  These beams, much like the wood under-framing in a pier and beam foundation, are designed to help carry the load of the interior weight.  They do not always run under major load baring walls, but the generally do.  Above is an example of a foundation layout plan.  You can see these beams are usually on 8-10 foot spans, sometimes as much as 15-18 feet apart, depending on the layout of your house.  The beams on the house in the picture are between 11-13 feet on center.  This will come into play when we are designing our repair plan.

The beams are the strongest part of your foundation.  They are the best area to both press the piers off of, and to lift the home as well.  Any repair plan should have the piers placed under the BEAMS, not under the walls.  If the beams are under the walls, then that's even better :).  When you straighten out the foundation, you will, in turn, account for and correct most of the associated damage that came with the foundation failure, but placing the piers under the section of the home that is not a under foundation beam is risky business. The small slab on top of these beams can not withstand the force of driving piers or lifting the home, and can easily crack.  The cracking of the slab can lead to lingering long term effects.  If the slab cracks, it can lead to constant issues with flooring (tile can continually crack), and moisture intrusion through the slab.

So where do you place your piers?  At the beam intersections.  If the span of those beams is too great, you might need to place intermediate piers along those beams in order to support the weight of your home.  If you have a two or three story house, and your beams are 12-15 feet on center, you most likely will need intermediate piers between the intersections in order to account for the weight of the home.  Look at the example of the repair plan on the inset picture.  This is the same house as the foundation plan previously shown.  Notice the intermediate piers in the middle portion of the home?  Those were needed to sufficiently lift and stabilize this specific house.

Make sure that your foundation repair contractor is following the layout of your foundation, and not just placing piers in low areas or under walls.  Getting this wrong can lead to continual problems with your home and your foundation.

If you have any questions, or are in need of foundation inspection, look us up here.

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