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Serving NORTHERN VIRGINIA,
MARYLAND, D.C. Metro area

basement waterproofing A angieslist rating

They finished the job and had the job site cleaned up in less than a day. My wife and I were amazed!

Cause

When your home was built, an area approximately 6 to 10 feet from where your house is currently located was excavated, footings were formed, your walls constructed, etc. (See Understanding Residential Foundation Construction). Then that area was in most situations, backfilled with the same clay that was originally excavated. Damage to foundation walls is caused when marine clays are used as backfill. This practice, now prohibited, but County inspectors do not sit around job sites watching as crews place backfill. Code violations are something that we find on a regular basis when conducting inspections - and it does not matter if the home is worth $100,000 or $5,000,000. New Home Building Contractors love to skimp and save money wherever possible.

In any case, this soil was not properly compacted to what we call a pan hard density. It was loosely backfilled, and rightfully so. Otherwise, the compaction would have imploded the walls that were not fully cured to begin with. As the years went by, and your house aged, the soil around your home compacted. During dry periods, the clay shrinks, settles into the voids left by the moisture, and then when the moisture returns, swells again. Damage is caused from these yearly cycles of pressure exerted by shrinking and swelling of the marine clay in the backfill. See figure 3. Swelling pressure of the soil can be compounded by improper drainage around the house from rainwater.

Cracking

All concrete structures will crack to some extent. Concrete will crack due to tensile stress induced by shrinkage or stresses occurring during setting or use. Contractors pour walls, or build block walls, and before the concrete and/or mortar can cure properly or adequately, up goes the rest of your home, and there is the stress we are talking about. In many large structures, expansion and contraction joints or concealed saw-cuts are placed in the concrete as it sets to make the inevitable cracks occur where they can be managed and out of sight. In residential construction this rarely occurs.

Shrinkage cracking

Shrinkage cracks occur when concrete members undergo restrained volumetric changes (shrinkage) as a result of either curing or drying, self-generated shrinkage or thermal effects. Once the tensile strength of the concrete is exceeded, a crack will develop. The number and width of shrinkage cracks that develop are influenced by the amount of shrinkage that occurs, the amount of restraint present and the amount and spacing of reinforcement provided. Some cracks are immediately apparent, visible within 0 to 2 days of placement, while drying-shrinkage cracks develop over time.

Tension cracking

Concrete members may be put into tension by applied loads. The size and length of cracks is dependent on the magnitude of the bending moment and the design of the reinforcing at the point under consideration.

Porous Concrete Block

When water comes into contact with concrete block, the concrete block soaks up the water like a sponge, at which point, the acid starts to corrode and weaken the block and the mortar that holds it in place. This can ultimately result in a weakened block wall, which can then bow inwards, as illustrated above.

Northern Virginia Basement Waterproofing
Alexandria, Arlington, Falls Church, Reston, Springfield

Solution

Depending on the extent of damage, foundation walls may need to be replaced while others can be repaired. Interior solutions can be wall bracing, I-Beams, Carbon Fiber, epoxy injections, interior drain tiles, and other types of repair. We now have interior elastomeric applications to waterproof concrete blocks from the inside, if the block is unfinished. Outside solutions involve excavation, crack repair, wall rebuilds, helical piers and anchors, home leveling, waterproofing, drain tiles, etc. To prevent future damage, the clay must be removed and the backfill replaced with, according to code, a minimum of fifty-one percent (51%) sand and/or gravel.

Indicators of Expansive Soil Movements

Listed below are indicators you can look for to determine possible expansive soil related movement and / or structural damage. The probability that your foundation has experienced some movement increases with the number of indicators observed, their frequency, and location in the structure.

Northern Virginia Basement Waterproofing

Exterior Indicators:

Diagonal (stair stepping) Cracks in brick walls. Cracks may go through brick or mortar and vary in width
Sagging brick lines when sighting along a wall
Bowed or non-vertical walls
Separation of wood trim joints at corner
Separation of concrete driveway, patio, or sidewalk from foundation
Tilting of landscaping/retaining walls