Sooner or later, you will probably experience some kind of foundation problem. Why? Because unstable soil conditions in this part of the country inevitably produce excessive settle mut.
The worst type of unstable soil is gumbo clay, which swells when it comes in contact with moisture and then shrinks when the water evaporates. Most South Texas soils consists mostly of gumbo clay. With the hot dry weather and extreme South Texas temperatures, the surface of the soil expands and contracts over and over again, slowly causing your foundation to shift and eventually crack if you do not take the proper precautions. Although people are very concerned about keeping up their lawns and flower beds, few ever take the time to think about maintaining their foundations. Watering the slab manually with a hose is the most economical way to keep a slab wet, but it is also the most time consuming. A soaker hose can be purchased at a home improvement store and placed around the perimeter of the slab. Ideally, a timer might even be attached at the hose bib to turn the water on and off automatically twice a day.
If there are large trees in close proximity to the foundation, extra care should be taken to provide enough water to maintain both the tree and the slab. Also, if the roots of the tree threaten to interfere with the foundation, the roots should be pruned or a barrier should be installed to separate the roots from the slab. Otherwise, the tree may eventually have to be removed.
Additional measures can be taken to bring a more preventative measure to foundation settlement caused by trees and their roots. The #1 cause for all foundation settlement is that the soil under your foundation does not contain enough moisture.
Trees are a valuable asset to your property. However, when they’re close to your home, they can cause problems in their search for water. Roots will grow underneath your house and take water from the soil. A single tree can remove as much as 150 gallons of water from the soil each day! (Shrubs and other plants also remove large quantities of water.) Without that moisture, the soil will contract to cause a strain on the foundation.
Biobarrier® has been used for years to prevent tree root damage to sidewalks, parking lots, and roadways and is now being used to protect foundations. It is designed to be placed between tree roots and the home’s foundation to prevent the growth of tree roots under the foundation. With a 15-year guarantee, it is made of a geotextile fabric with permanently attached nodules containing trifluralin. The nodules slowly release trifluralin to prevent any root growth in the area.
The trifluralin creates a two-inch vapor zone on either side of the fabric, causing the roots to cease to grow or grow away from the zone. Trifluralin has been used in agriculture for more than 20 years, and it decomposes in the soil quickly, having less toxicity than that table salt or aspirin. If your house is at the age when settlement begins to occur, and that big tree is too beautiful to cut down, call us for a free estimate to have Biobarrier® installed at your home and STOP settlement before it starts!
Completed Projects (an excellent maintenance tool for completed foundation projects)
Installing a water system to prolong the life of your foundation is simple for any do-it-yourselfer. Just follow these easy-to-understand instructions, and you could be adding years to the life of your foundation.
The first thing to remember is to keep 12 – 18 inches away from the slab. It is best to bury the hose a couple of inches, but the system can be started with the hose on the ground’s surface.
You have the system in; you are ready to set the timer. We suggest setting the timer for 15 minutes twice a day at the initial start-up, for instance, at 7 am and again at 7 pm. During the dry summers, you may have to set the timer for 3 – 4 times a day and cut back to once a day during wet winters. Some personal judgment must be used in the amount of time to operate the system. DO NOT OVERWATER.
This information is just a guide in the installation and operation of your watering system. Also, a physical guide for ensuring proper slab watering is to check your foliage and plants nearby. If these are healthy in appearance, then your slab will generally be healthy.
With a slab foundation, the beam is the thick part of the concrete slab, intended to support the weight above it without sagging or bending. With the proper steel reinforcement, most slab beams, also called grade beam, will not sag with supports no further than 8 feet apart, depending on the weight.
BEDROCK, or POINT OF REFUSAL a hard, solid earthen area that lies beneath the surface soil, that usually requires blasting or jack hammering to be excavated.
BELL, or BELL BOTTOM PIER a concrete constructed pier that spreads outwards, wider than the pier shaft, producing more bearing support at the bottom, such as a spread footing.
BENCHMARK a reference point with a fixed location and height that does not change. The foundation can be compared to the benchmark and a determination can be made if the foundation is moving up or down.
CANTILEVERED means supported only at one end. Some structures can be designed to be cantilevered, and the unsupported end will not sag. In some cases, however, the structure is not designed properly to be cantilevered and supports are required to support the cantilevered end. Oftentimes, a girder under the house is cantilevered, and needs a support at the end for the foundation to be leveled and all sags taken out.
CONCRETE a hard substance made of sand, rocks, cement, and water. Concrete can have other ingredients added for color, resistance to water or heat, and other additives. Any additive can potentially weaken the concrete. Most foundations are designed with concrete poured at 2500 psi. This is also called 5 sack cement, because it should have about 5 sacks of cement per cubic yard of concrete, insuring it’s strength. 6 sack would be about 4,000 psi. Too much sand, or too little cement, will weaken the concrete.
DEAD MAN a large weight, made usually of concrete, used as an anchor and usually buried underground, to keep a wall from pulling away from the hill. It is also called a foundation pier made up of a large block of concrete under the structure that cannot be adjusted or altered without breaking it out. It is the most undesirable of all foundation repair techniques and repair methods, because it cannot be adjusted.
DIFFERENTIAL SETTLEMENT means that different parts of the structure are settling at different rates, causing cracking and pulling apart of the structure. Is different than subsidence.
ENGINEER a highly skilled and educated designer and planner of various fields. In Texas, to be called an engineer, one must first have a degree in engineering, then work for 4 years under the guidance of a registered engineer, then be approved by the State Engineering Board. After the degree in engineering, one can be called a graduate engineer only. A foundation engineer is one that specializes in the planning and construction of foundations, but is usually under the auspices of civil engineering. A structural engineer is primarily concerned with the mathematics and physics of structures. A civil engineer is involved in the planning and building of bridges, highways, drainage facilities, canals, and foundations. To repair a foundation, the most qualified engineer is one who has both experience and education in civil engineering.
Foundation repair experts must understand all the techniques of building construction, common structural defects, drainage problems and repair methods, different foundation repair techniques, and some knowledge of soil hydrology and the local geology. A good civil engineer must be prepared to crawl under a structure to inspect for defects and drainage.
Engineers not usually qualified for foundation and drainage repairs are mechanical engineers, aerospace engineers, software engineers, and electrical engineers.
ENGINEER’S REPORT an inspection of a structure, residential or commercial, whereas a licensed engineer registered with the State from which the structure lies, completes a visual inspection of the structure, detailing what he or she believes are flagrant defects of the structure. A normal engineer’s report will list observations, make a conclusion from those observations, and make detailed recommendations how those flagrant defects should be corrected. An engineer’s report is sometimes limited to the economic condition of the area surrounding the structure and other factors. An engineer’s report is limited to the substructure, and does not usually concern the superstructure. One engineer’s opinion may differ from another, depending on what each may call a flagrant defect, and one engineer may recommend a foundation repair that may be different from another engineer.
EXPANSION JOINT a flexible joint between two parts of a structure to allow for expansion and contraction of the two parts, preventing structural distress.
FILLING THE VOID a process by which a large void is filled, but not necessarily with pressure. In this process, a large area of a void can be filled quickly, leaving the last little bit for polyurethane injection.
FILTER FABRIC a material that allows water to pass through, but not soil particles or rocks.
FLAT WORK a section of concrete that is about 4 inches thick.
FLOATING SLAB a slab usually about 4″ thick inside a foundation wall but not attached to the wall or foundation. A floating slab is usually just poured on grade and has no piers underneath. Many are constructed with little or no reinforcement and simply provide a concrete floor to walk upon instead of dirt.
Most all pier and beam homes have a floating slab in the garage. The only way to raise a floating slab that has settled is by polyurethane injection.
The original idea of installing a floating slab is that it was thought it would “float” with the swelling soils instead of the expansive soil crowning the floor. However, it is of poor design and should not be used if possible.
If you don’t want swelling soils, install drainage. Water causes the soil to swell. A monolithic slab is better than a floating slab, and its design has good structural integrity.
FOOTING a concrete slab, usually 8 inches to a foot thick, placed under the perimeter or the interior of a foundation. A continuous footing is a concrete foundation footing that runs around the edges of a structure.
FASCIA (upper exterior trim board) also called a frieze board, a horizontal, decorative band of wood around a house where the siding meets the roof members. Where fascia boards are separated at a corner is a common sign of foundation settlement of that corner. The corner of the wall will rotate outwards as the structure settles, pulling the fascia boards apart.
GRADE BEAM the perimeter band of concrete thicker and deeper than the remainder of the concrete slab foundation, or the interior strip of the concrete slab foundation that is thicker and deeper to allow for the support of the above loads. The grade beams will support above loads with less bending and deflection than the usual interior of the slab, which is usually only about 4 inches thick. Most grade beams under residential construction are about 10 inches thick and about 2 feet tall. If a load-bearing wall was placed on a 4-inch thick of slab, without a beam, it might likely sag downwards in the future.
HELICAL PIER, the HELICAL SCREW ANCHOR a foundation repair system that acts like a screw and is screwed into the soil or rock, meeting enough skin friction that it should support most loads. However, in clay soils, once the clay shrinks in dry conditions, the skin friction decreases, causing the helical pier to fail. Helical piers can sometimes be successfully anchored into rock and used as a tieback for retaining walls but should never be used as a tieback when screwed into soil.
LOAD BEARING CAPACITY OF EARTHEN MATERIALS Solid rock 100 tons per square foot
Soft rock 8
Compact Gravel 10
Loose Gravel 4
Hard clay 4
Soft clay 1
Coarse sand 3
Fine sand 1.5
Soft soil 1/2
LOAD BEARING WALL
a wall of a structure that can successfully transfer weight from a ceiling area to the foundation without distress or bending. The weight above a load bearing wall must be carefully supported before it can be removed, and usually a header or beam can be installed in it’s place. Non load bearing walls can be removed usually without the danger of the weight above collapsing. Removing walls should only be attempted by a professional contractor, because it can be dangerous to the future occupants of the structure.
MONOLITHIC SLAB a concrete slab foundation poured all at one time.
MUDJACKING a process by which concrete flatwork can be raised by pumping a soil/cement slurry under the concrete with enough pressure to literally “float” it up to a more desirable level. Raising concrete with concrete beams or uneven weight is difficult with mudjacking, and usually nets poor results. Mudjacking must be done from above, and never from the side of the area that must be raised.
PIER a support under a foundation. can be wood, steel, concrete, in the ground or above the ground.
PIER AND BEAM a type of construction, primarily in residential construction, by which the foundation is formed with individual piers along with a concrete beam or wood beam spans. In a pier and beam home, one can usually crawl under the structure, and cross ventilation is necessary to air out the crawl space. In a pier and beam home, the floors are usually wood.
PIER CAP connects a support system to the structure.
PILING a pier that is driven or pushed into the soil. A standard piling typically used in foundation repair uses the weight of the structure to push the piling into the soil. Other names in the foundation industry circulate as segmented pilings, push pilings, pile blocks, steel pilings and concrete pilings, and then there is the double piling, which is two pilings close together. A pile is a support that is PUSHED into the earth (displacement pile), rather than a pier that is an open hole that is filled with concrete to construct a pier support (replacement pile). With any pile, in clay soil, the idea is to transfer the structural load into the ground to a more competent or stable strata by pushing the pile into the soil. In sandy soils, friction plays the larger part into developing support on the edges of the pile, but clay soils can also develop outside wall friction with the soil and add to the support of the pile.
POINT OF REFUSAL a point at which a piling can no longer be “pushed” into the soil without breaking or lifting the structure above. A light structure will reach a point of refusal at a shallow depth because it has less weight to push against. A heavy structure will allow the piling to be pushed deeper, until it reaches a hard change of soil or rock, or it develops enough skin friction around the pile to reach a ‘point of refusal’.
A point of refusal in dry soil may not be sufficient to support the weight above during wet conditions.
REBAR an abbreviation for the term metal reinforcement bars, used to strengthen concrete and help prevent separation of the concrete, especially in a foundation pier, footing, or slab. 1/2″ is commonly used in most concrete floor slabs, called #4 rebar. #6 is 3/4″, usually used in the concrete grade beam of a slab, and #3 rebar is 3/8″.
ROOT BARRIER a method by which the roots of a tree are severed between the tree and a structure, and a horizontal ditch is placed between the structure and the tree, lined with a variety of materials that may prevent the tree roots from growing back. This is a defective measure designed to prevent the tree roots from drinking too much water under the foundation, ultimately damaging the foundation structure. If the tree roots were truly a problem, then all the trees and the neighbor’s trees would all have to be cut down. Cutting the tree roots are hazardous to the tree, and most foundation systems are not so fragile that some shallow tree roots could cause a problem.
SETTLEMENT the downward movement of a foundation. Differential settlement means that different part of the structure are settling at different rates, causing cracking and pulling apart of the structure. Is different than subsidence.
SHIMS thin spacers placed between a support and the foundation of a structure, usually very thin to cover a small space. Shims are generally made of metal.
SHIMMING to install shims on top of the piers and supports, under a foundation, usually making small adjustments to the level of a foundation, without the further installations of additional supports.
SLAB FOUNDATION a type of construction whereas the floor is concrete, usually poured monolithically, supported by concrete beams. The size, width, and location of the concrete beams of a slab foundation depends upon the design and weight of the structure. A slab foundation without the proper steel reinforcement will not hold together.
STRING LEVEL a method of horizontal measurements with a long string, and a small level with a bubble in it that sits on the string. Once the string is stretched tight, and the bubble is in between the two lines in the level, the two ends of the string will be level to each other, allowing one to make a mark.
STRUCTURAL INTEGRITY possessing the strength to support the load as it was designed.
SUBSIDENCE a sinking to the bottom, different than settlement, usually caused by the removal of oil and gas, or mining, but can also be caused by the lowering of the water table, causing the structures above to sink.
SUBSTRUCTURE an area of a structure that involves the floor and everything below the floor.
SUPERSTRUCTURE an area of a structure that involves everything above the floor.
A typical engineer’s inspection of the foundation and structure does not usually include the superstructure. To include the superstructure, the engineer must be prepared to thoroughly inspect the attic for proper bracing, collar ties, and supports, as well as attic ventilation and ceiling/wall inspections.
A superstructure inspection is usually an additional price over and above the normal foundation inspection by an engineer.
UNDERPINNING (pressed pier) supports of various kinds added under a structure to assist in the vertical support of the structure. Underpinning can be defined also as piering, and there are a multitude of different kinds of piers.
UNSUPPORTED WALL a load bearing wall of a structure that lacks foundation support. An unsupported wall can create a sag in the floor. Some unsupported walls are built in between the floor joists, causing a sag, and others are built in between the foundation girders, causing a sag. Sometimes a load bearing wall over a thin slab can cause it to sag where an interior grade beam should have been installed. Piering under the unsupported wall will usually correct the situation if the piers are installed close together.
UPHEAVAL the rising of a structure caused by swelling soil, swollen because of an accumulation of water.
WEEP HOLE an opening in the bottom of a brick wall that will allow water in the wall to escape. A weep hole can also allow air to circulate inside the wall, like ventilation. Unintended consequences, however, allow a weep hole to be a home for insects and bugs, and it also allows water an unrestricted passageway into the home. Some houses have no weep holes at all, and it seems to have no effect.
WING WALL a brick or stone wall usually protruding from the front corners of a home. Some wing wall foundations are attached to the foundation of the home, and some are not. Some wing wall brick or stone is laid with the brick or stone of the house, and some are detached. A wing wall that has rotated to one side or to the end can usually be piered and jacked back up to vertical.