Glossary
Every term on a Grand Junction foundation quote
Foundation quotes and engineer reports are written in a vocabulary nobody teaches homeowners. Here is the whole of it, in the words a person would use.
- Active zone
- The depth of soil whose moisture content changes with the seasons and with what happens on the surface. Everything above the bottom of the active zone swells and shrinks. Piers are designed to reach below it, which is why pier depth is a soil question rather than a price question.
- Bearing stratum
- The layer of soil or rock strong enough to carry the load of the house without further compression. On Grand Valley lots this is often denser alluvium or weathered bedrock, and the depth to it varies from one lot to the next.
- Bell bottom pier
- A drilled concrete pier flared out at the base to spread load over a wider footprint. Common in older Front Range and western Colorado construction, and still specified where drilling is easier than driving.
- Bentonite
- A clay mineral group, mostly smectite, formed from weathered volcanic ash and notorious for swelling several times its dry volume when it takes on water. Bentonite beds occur within the Mancos Shale, which is why some Grand Valley lots move far more than their neighbours.
- Bowing wall
- A foundation wall bending inward under lateral soil pressure rather than dropping. Recognised by a horizontal crack near mid-height and by measuring the wall out of plumb.
- Carbon fiber strap
- A high-tensile fabric strap bonded to the inside face of a foundation wall with structural epoxy. Holds a wall that has already stopped moving and is specified within a deflection limit, commonly around two inches.
- Crawl space encapsulation
- Sealing the ground and lower walls of a crawl space with a reinforced vapor barrier so soil moisture stops evaporating into the floor framing above. Distinct from insulation and from drainage, though the three are often done together.
- Creep
- Slow, continuous deformation under sustained load. Distinguished from settlement in that it has no clear start and may never stop entirely.
- Deflection
- How far a wall or beam has bent out of its original line, measured in inches. The single number that decides whether a bowing wall gets carbon fiber, steel bracing, or anchors.
- Desiccation
- Soil drying out and shrinking, opening the polygonal cracks you see across bare ground in late summer. The other half of the expansive soil cycle, and just as damaging as swelling because the foundation loses support.
- Differential settlement
- The part that breaks houses. A building that sinks uniformly stays intact; one that sinks more at one corner than another racks the frame, which is where the diagonal cracks and sticking doors come from.
- Efflorescence
- The white crystalline bloom left on concrete or masonry when water passes through and evaporates, depositing dissolved salts. Not damaging in itself, but proof that water is moving through the wall.
- Elevation survey
- Measuring relative floor heights across a level with a laser or a water manometer to map where the structure has moved. The difference between a diagnosis and an opinion.
- Expansive soil
- Soil containing clay minerals that increase in volume when wetted and shrink when dried. The dominant cause of residential foundation movement across western Colorado and the reason drainage matters more here than concrete strength does.
- Footing
- The widened concrete base beneath a foundation wall or column that spreads the building load into the soil. Piers work by transferring the footing load onto something deeper.
- Frost depth
- The depth to which soil can be expected to freeze in a given jurisdiction. Footings are required to bear below it so freezing ground cannot lift them. The required depth is set locally by the building department.
- Grade beam
- A reinforced concrete beam spanning between piers or piles, carrying wall loads across soil that is not trusted to bear directly. Common in engineered foundations on expansive soil.
- Heave
- Upward movement of a foundation when the soil beneath it swells. The opposite of settlement, often mistaken for it, and requiring a different repair. A heaving slab is not fixed by piering the perimeter.
- Helical pier
- A steel shaft with welded helical plates that is screwed into the ground with a hydraulic drive head. Installation torque correlates with capacity, so each pier is verified as it goes in. Preferred on lighter structures that cannot provide reaction for a push pier.
- Hydrostatic pressure
- The pressure exerted by standing water in the soil against a foundation wall. Rises sharply when drainage fails and is the usual force behind a bowing basement wall.
- Lateral load
- Horizontal force on a foundation wall from soil, water, and surcharge such as a driveway or vehicle parked near the wall. Walls fail in bending under lateral load, not in crushing.
- Mancos Shale
- The Cretaceous marine shale formation that underlies much of the Grand Valley and forms the pale grey badlands around it. Weathers to a fine, clay-rich, often sulfate- and selenium-bearing soil that is both expansive and aggressive to concrete.
- Manometer survey
- A floor elevation survey performed with a water level rather than a laser. Slower than a laser but unaffected by furniture and sightlines, and still used by many inspectors.
- Mudjacking
- Lifting a concrete slab by pumping a cementitious slurry beneath it through holes drilled in the surface. Cheaper than foam, heavier, and needs larger holes. Also called slabjacking.
- Negative grade
- Ground that falls back toward the house instead of away from it, delivering surface water straight to the foundation. One of the most common and cheapest defects to correct.
- Polyurethane foam injection
- Lifting a slab by injecting a two-part expanding structural polymer beneath it through small ports. Light, fast, waterproof, and cures in minutes, which is why it has largely displaced mudjacking on residential flatwork.
- Push pier
- A steel pier hydraulically driven to bearing using the weight of the structure itself as the reaction force. Each pier is effectively load tested during installation, which is its main advantage. Needs a structure heavy enough to push against.
- Slab-on-grade
- A foundation where the floor slab sits directly on prepared ground with thickened edges or a perimeter footing, and no basement or crawl space beneath. Common in newer Grand Valley construction and the type most sensitive to soil heave.
- Stem wall
- The short foundation wall between the footing and the framed floor, standing above grade on a crawl space or slab foundation. Where spalling, exposed rebar, and sulfate attack usually show up first.
- Sulfate attack
- Chemical deterioration of concrete by sulfate salts in soil or groundwater, which react with cement paste and cause expansion, cracking, and softening. Soils derived from Mancos Shale can carry meaningful sulfate levels, which is why sulfate-resistant cement is specified on some sites here.
- Underpinning
- The general term for extending an existing foundation down to better bearing, whether with piers, piles, or mass concrete. Piering is the form of underpinning nearly always used in residential repair.
- Wall anchor
- A plate buried in stable soil out in the yard, connected by a rod to a plate on the inside face of the foundation wall. Tightening the rod resists further movement and can, over seasons, recover some of the wall position.
Where these terms turn up
- Why Grand Valley soil moves covers expansive soil, bentonite, desiccation, and heave.
- Pier types compared covers push piers, helical piers, and bearing stratum.
- Bowing wall repair options covers deflection, lateral load, and wall anchors.
- The cost guide puts a price against most of them.
Find out what the repair costs
Ring (970) 644-6329, or send the form, and a Grand Valley foundation contractor prices the work at no charge.