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foundation repair philadelphia pa

Types of Foundation Cracks


Foundation cracks have many causes, but the cause of the crack can usually be determined by the type of crack, as can the solution to the crack problem.

Vertical crack:  A vertical foundation crack is a crack that goes straight up and down or slightly diagonal, within 30 degrees of vertical. 

Vertical cracks are of least concern and are commonly seen almost all houses.  They occur because concrete is very strong under compression but cracks easily under tension.  Most houses will see one or  two  form within the first years after construction.  These cracks are not a real structural concern. However,  they can allow seepage of water through the foundation wall during heavy rains.  The solution to vertical cracks is usually simple, inexpensive and permanent.  These are the easiest cracks to fix.  The experts at Basement Solutions 911 can assist you with long term and inexpensive solutions.

Diagonal Cracks: A diagonal foundation crack is one that runs from about 30 to 75 degrees from vertical on the wall.

Many times, diagonal cracks with be wider at one end than at the other.  At times the crack will be very narrow .  Diagonal cracks are usually caused by differential settling of the foundation.  Differential settling is cause by a change in the ground conditions under the foundation footings.  One part of the house’s foundation settles a little into the ground while the rest of the foundation stays supported.  This causes a tension on the foundation.  This tension is not in a straight horizontal vector, but horizontal and vertical.  The foundation cracks, but at an angle rather than straight up-and-down. Because the foundation is moving in two directions, part of the crack is also wider and will indicate the exact settling area.  This differential settling could be cause by the house being built on a hill, orchanges in the soil conditions because of excessive rain or drought. 

Horizontal Cracks: Foundation cracks that run sideways are the most serious type of cracks. 

They are sometimes seen in poured concrete foundations.  However, they are more common in concrete blocks .  Horizontal cracks are caused by a bowing foundation.  The foundation wall’s exterior is usually covered by a backfill of dirt and gravel.  If this backfill is improperly done, pressure against the foundation wall cases it to bow inwards.  Sometimes there is excessive rain which can also be followed by a freeze.  This can increase the hydrostatic pressure behind the foundation wall and cause it to bow inwards (right).   Bowing foundations are serious and can lead to structural failure of the foundation.

There are a couple of different techniques for fixing horizontal foundation cracks.  Some involve the installation of high-strength strapping on the interior of the foundation to keep the wall from bowing further.  Also,  number of reinforcing posts or braces are installed in the basement of crawlspace.  There are also techniques that use anchors buried in the surrounding soil that pull the foundation wall back out and secure it.

Regardless of the solution, the a bowing foundation should always be evaluated by a licensed Structural Engineer..  Bowing foundations are serious and their repair should always be done by a professional.  At Basement Solutions 911 we can assist you in this process.

Foundation cracks can be a serious issue.  Please call us at 610-495-9111 or visit us at http://www.basements911.com if you see any cracks on your concrete slab or foundation.  We will provide you with a FREE inspection and our work has a guaranteed for life.