Here in Costa Rica, concrete construction is the most common method and is accepted by the majority of the buyers. Homeowners and buyers may notice problems such as cracks in floors and walls and doors and windows that do not open and close properly, all of which indicate concrete and moisture variations.
Settlement of concrete floors and walls is often the result of variations in moisture and density of the soil beneath the concrete floors, as well as seismic movement. A settling concrete floor can cause major structural problems in a home. For example;
Natural Soil – especially clay, beneath a concrete floor can dry out and shrink over time due to moisture variations.
Fill Soil – during the construction of dwellings, layers of soil are commonly moved around and spread out to bring the level of the ground to the desired level.
When the structure is built, the concrete foundation may not be deep enough to extend to solid ground below the fill soils, and the concrete floor may be sitting directly on the ground that has been filled.
Loosely compacted fill soils can consolidate beneath the weight of the floor, causing an open space or void in the soil below the floor. This condition creates open spaces under floors referred to as “voids”, and if the floor isn’t strong enough to span the void, the floor will settle and crack.
Uneven Floors – typical in older homes. If the floor slopes towards an outside wall, there’s a good chance that the house has structural foundation problems.
Subterranean Installations – water tubes and drains installed below concrete floors can condensate and possibly leak, allowing the soil to condense under concrete floors and foundations.
Horizontal Foundation Cracks – it’s not uncommon to find cracks in concrete foundations, especially poured solid concrete. This is common in new construction as well as existing dwellings. While there is a great deal of engineering that goes into determining if cracks are serious problems, there is one rule that you should never forget. Horizontal cracks are more problematic than vertical cracks, depending on their size.
Harmless Cracks – Poured concrete shrinks as it cures and shrinkage cracks in new dwellings are common. They can be small vertical cracks or small cracks at door and window openings. If these cracks are thin, they won’t affect the structure. The only concern is leakage. If you see small cracks in your walls, don’t panic, but consult with an experienced professional if they become larger.
Plaster Cracks – Few things are more misunderstood than concrete or drywall plaster cracks on the inside of dwellings. The following crack types are not generally related to structural movement: We call these “stress cracks” or “surface cracks”: a small crack, less than 1 /8 inch, that follows the corner of the room where two walls meet small cracks that extend up from the upper corner of a door or window opening
The following cracks are related to structural movement:
- cracks larger than 1 /4 inch in width, or cracks that have a lip, where one side of the crack is elevated above the other side of the crack.
- cracks that run diagonally across the wall, or in a stair step fashion.
- cracks on the interior finish that is in the same vicinity as cracks on the exterior of the house.
Some folks have been told that removing and replacing floors and walls is the solution to fix their structural concrete problems. However, because the most common problems are a result of the lack of compaction of the soil that was used to fill the building site, rather than with the construction of concrete floors and walls, removing and replacing concrete on top of the same soil will not solve the problems.
Structural damage and cracks can be repaired with a number of proven methods and an experienced construction inspector can help you understand your structural issues and recommend the most cost-effective solutions. Here are a few proven construction methods to be considered to solve structural issues:
Buttresses – an architectural structure built against or projecting from a wall which serves to support or reinforce the wall. Buttresses are fairly common on older buildings, as a means of providing support to act against the lateral or sideways forces arising out of the roof structures that lack adequate bracing. The term counterfort can be synonymous with a buttress, and is often used when referring to retaining walls and other structures holding back earth.
Furthermore, flying buttresses are included in several traditional architectural styles.
Additionally, brick and masonry buttresses can be also utilized to support weak wall corners and walls.
Columns – are structural elements that also have certain proportional and decorative features. A column can also be a decorative element not required for structural purposes. Columns necessary to support beams or arches that support the upper parts of walls, floors or ceilings are referred to as “engaged columns”.
Engaged columns serve a similar structural function like buttresses and are finished to be ornamental in certain traditional architectural styles.
Steel tie-backs – steel tendons or helical anchors drilled into the face of walls to extend beyond the soil in order to apply pressure to the wall, provide additional lateral support. With one end of the tieback secured to the wall, the other end is anchored to a stable structure, such as a heavy block of concrete which has been installed in the ground or pilings driven into the earth with sufficient resistance. Tiebacks are designed to secure and stabilize walls from movement and are also used to pull the wall back to its original position.
Steel channel columns – steel I-beams can be utilized to support concrete walls during and after construction as well as straighten and strengthen damaged walls.
Additionally, they can be installed to shore up walls that have moved as a result of soil movement or erosion.
Sister walls – these are concrete and steel reinforced walls that are installed adjacent to damaged walls that are cracked and or have structural settlement. Steel rebar and threaded rods with steel plates and nuts can also be used to attach the new sister wall to the existing wall.
In some cases, people try quick-fix solutions to cosmetically conceal concrete cracks caused by settling. A common repair is patching over cracks, and while this temporarily conceals the damage, it does nothing to prevent it from happening again.
Another common fix that homeowners attempt, is filling in exterior cracks with caulking or mortar products. This too is temporary, as the cracks will open back up as the problem continues. Repeated caulking repairs often result in varying textures and colors of the exterior surfaces.
Another important factor to consider is the resale value of your home; since most people sell their home at some point during their life. You know yourself that you would be hesitant to buy a home with a structural defect. When a prospective buyer hires a construction inspector, prior to closing the sale, the inspector will reveal the concealed problems that will affect the value and saleability of the home.
If you noticed any of the following conditions in or around your home, contact an experienced construction inspector to provide you with recommendations for repair before these conditions worsen.cracks in walls or floors that include uneven concrete or settling
- cracks in walls or floors that change in size
- a wall that bows or tilts inward
- stair step cracks in concrete block walls
- uneven, sinking or bouncy floors above a crawl space or basement
- cracked plaster or brick on a building’s exterior
- concrete floors in garages, sidewalks or patios that have cracked and shifted
- cracks or settlement in retaining walls
You don’t need to be an expert to recognize problematic concrete issues, but you should contact an expert to inspect the damage and determine how to properly correct the problems. The conditions that caused the damage usually aren’t obvious. It’s a common mistake to treat the problems cosmetically by filling in cracked concrete, instead of addressing the actual construction issues that caused the damage. When only superficial strategies are used to conceal problems, the damage will reoccur and worsen. Do yourself a favor and contact an experienced construction inspector to solve your problems correctly before they become worse.
The writer, Tom Rosenberger has lived and worked in Costa Rica for 24 years and from his travels throughout the country building housing and inspecting construction, he has acquired a wealth of knowledge about construction here.
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