Carl Brahe
Structural Problems can be the most costly to fix, but the signs are often dismissed as normal aging or settling. Many structural problems cannot seen without digging up the foundations and opening walls, but there are usually visible symptoms. If the foundation, or load bearing structure, is damaged, cracks, uneven floors, or doors and windows that don’t work right, usually result.
If someone tells you that cracks, or other signs of settling, are normal and nothing to be concerned with, take a close look yourself. Do you think, "It’s nothing to be concerned about?" Cracks in foundations and distorted floors, walls and ceilings usually have some consequence to the building in the long term.
Vertical, or horizontal, hairline cracks in the foundation usually do not threaten the structural integrity of a house. Cracking from drying of concrete or drywall tape, or slight settlement of the earth beneath the foundation, are usually not a concern.
Buildings move continually as the framing shifts and the soil contracts and expands, with changing heat and humidity. Most of the time, these movements are so small that they are unnoticed, but many older homes were built relying on gravity and friction to hold building components in place. With time the structure gets weak and the building settles and spreads. These buildings will eventually collapse under their own weight if not remediated. Newer buildings have all components tied together to avoid this making the entire structure a single unit instead of a series of unconnected components.
Some defects are hidden under ground and inside walls. Others, like improper drainage that allows runoff to drain toward the foundation, are obvious. If water from runoff, sewer back-up, or misguided landscaping sprinklers, runs to the foundation look carefully for structural damage. Structural damage is often caused by uncontrolled moisture.
If water penetrates the foundation leaving behind tale-tell salts, you know the drainage problem has existed for a while. The salt washing through a foundation will eventually rust away rebar and wire mesh causing the concrete to crumble and the foundation to fail.
Chronic leaks in roof, siding, windows, doors, or plumbing can supply sufficient moisture to cause wood to rot and lose structural integrity. In time, rot can turn lumber into dust. If you see signs of rot in the fascia, soffit, or trim around window and door frames, there is likely to be hidden damage.
Contact between wood and concrete, or wood and earth, can provide enough moisture to rot wood. Untreated wood will wick moisture from these sources and can rot from the inside out. This is a common defect in deck and porch columns and supports.
In areas where termites live, the earth to wood contact provides them access. Termites can turn wooden structure into powder quickly. Some termites use mud tubes to travel to food sources. Mud tubes identify the presence of these types of termites. If wooden structure touches the ground, expect hidden damage.
The most likely place to observe signs of structural damage is on the top floor. Shifting caused by foundation movement, or rotting structure, will be most pronounced at the highest level. A movement of the foundation will transfer to the all level above. Widow frames and door frames will shift more on the top level than below. Unsupported structure below will usually mean uneven floors above. Sometimes unethical remodelers will cover up structural defects to unload a property. Cover-ups don’t last long before the hidden problems begin to reveal themselves.
Use a small carpenters square to check the corners of window frames and door frames. If they are not square, a likely cause is movement in the structure below. They can also be out of square from improper installation. New installation can hide distorted framing.
If only one door frame, or window frame, is distorted, the cause is probably improper installation. Movement in the structure will likely affect more than one.
A dropped marble will reveal unlevel floors. Slightly unlevel floors are not necessarily bad. Some foundations, in expansive soil, are built to ride the soil movements like super slow motion ocean waves, allowing the whole structure to sway slightly. Buildings on this type of foundation may not be perfectly level. The floor may lean slightly in one direction. If the floor slopes in more than one direction, expect problems below.
Significant cracking can result from movement of structure. Cracks can reveal the location and the direction of the force that caused them. A stair step, or ‘V’ shaped crack may indicate pressure pushing upward. A vertical crack that is larger at the top than the bottom may indicate the same.
Upward forces result from soil expansion when moisture levels increase in the earth beneath sidewalks, driveways, patios, and foundations. If sidewalks and driveways are cracked and heaved or settled, chances are that expansive soil is present. Foundations for expansive soil either ride the expansions/contractions like a ship on a wave, or rest on pilings driven deep into the ground. A properly designed and installed foundation protects the structure above.
Basements in areas with expansive soil are built with float walls. A float wall has an area at the bottom of the framing that expands and contracts with soil movement. If rigid walls are installed, expanding soil can push on the walls with enough force to break the floors above.
Downward forces create opposite cracks from upward forces. Vertical cracks will be wider at the bottom than top and stair steps will be in an inverted ‘V’ pattern. Downward forces typically come from subsidence of the soil below the foundation. This can come from improper soil preparation before pouring the concrete, or from expansive soil drying and shrinking, or earth being washed away from under the foundation.
Inward or outward force may also damage the structure. Horizontal cracking is often not concerning, but when the surface above or below the crack has been forced inward or outward, there may be reason for concern. This type of cracking may be from impact like from a vehicle backing into a wall, from improper backfill, vehicle traffic too close to the foundation, or from pressure of moving earth and water. Bowing may also occur.
If you look closely at the indicators of structural problems, the clues usually reveal the source. If you determine the place, and direction, of force that distorts, or cracks, foundations and the structure above, the source is often obvious.
Not so obvious is the resulting damage that can occur in hidden places. A heaving in a section of foundation will push the walls above upward. This heaving might cause a distortion in fascia, trim joints, or window frames allowing moisture penetration. The water, once it has entry, will seek the lowest possible level. Water can run down from roof to wall to floor, spreading as it moves downward. Over time water penetration can cause rotting of wall, and floor, structural components that may not be discovered without opening walls, ceilings and floors to reveal it, or until the structure fails . The hidden nature of structural damage, and the need to deconstruct to correct defects, can make structural problems the most expensive and time consuming to correct.
When you consider buying a house, look at the sidewalks, driveways, and patios. If they are heaved or sunken, twisted or cracked, the property probably has expansive soils. Be extra careful in your personal inspection of the property. If the foundation and other structure are proper for the conditions, and the runoff and landscape water has been routed away from the foundation, and concrete pads, you will see little damage to outside concrete and no signs of structural problems inside.
If someone suggests, “It’s only a slight settlement crack.” look for yourself. Most properties built on expansive soils will have some defects from the constant expansion/contraction of the ground as moisture levels fluctuate. Evaluate signs of structural damage with your home inspector to determine if you should consult a structural engineer. The cost of a structural engineer may seem high, but compared to almost any structural repair, the fee is cheap.