Badger HomeownerWisconsin home guide

Old Basements and Foundations

Old Madison-area houses sit on stone, brick, concrete block or poured concrete. Each has its own normal cracks and its own real problems, and nearly all of the problems start with water. Here is how to tell them apart, drawn as diagrams rather than photos.

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Foundation Types

  • HUD's rehab inspection guide lists stone, brick, concrete and concrete block foundations, and says small-home foundation walls are usually masonry.(HUD)
  • Older, massive masonry is less brittle than thinner masonry built in the mid-1900s, which is more prone to stress damage.(HUD)
  • Wisconsin's Uniform Dwelling Code, with today's footing, dampproofing and drain tile rules, applies to homes started on or after June 1, 1980.(SPS 320)

Stone, Brick and Lime Mortar

  • Soft mortar is normal. Until about the end of the 1800s mortar was sand and lime. Soft mortar lets masonry absorb movement and can partly heal small cracks.(HUD) Buildings from 1873 to 1930 range from pure lime to lime-cement mortar; by the 1930s most masons used equal parts portland cement and lime.(National Park Service)
  • Inspect yearly. The Wisconsin Historical Society suggests an annual look at stone masonry. A building 100 or more years old probably has missing or crumbling mortar, caused mainly by moisture.(Wisconsin Historical Society)
  • Repoint with soft mortar. New mortar should be no harder and no less permeable than the old. Mortar stronger than the stone or brick won't give, so the masonry cracks and spalls instead, and that damage is permanent.(National Park Service)(Wisconsin Historical Society) HUD agrees: high-strength mortar over low-strength mortar can seriously damage masonry.(HUD)
  • Fix the water first. Leaking gutters, settlement or rising damp have to be dealt with before repointing, or the repointing is wasted.(National Park Service)
  • Don't sandblast or seal. Sandblasting and high-pressure washing damage stone and mortar.(Wisconsin Historical Society) Surface sealers rarely work and can make spalling worse.(HUD)

Concrete Block and Poured Walls

  • Block shrinkage cracks taper and widen as they rise, usually appear in the first year, sit in the middle third of the wall, and are rarely serious.(HUD)
  • Block holds water. The hollow cores let moisture move up inside the wall and can even pool in cold climates, so insulating a block wall from inside needs care.(DOE Building America)
  • Poured walls and floors. Cracks at corners and openings usually come from drying shrinkage early in the building's life. Floor-slab cracks are usually shrinkage or minor settlement and rarely harmful, but cracks near and parallel to the walls can come from wall or footing movement.(HUD)

Reading Cracks

Stair-step (settlement) Vertical (often shrinkage) Horizontal or bowing
Our diagram of the patterns HUD's rehab guide describes. Red marks the crack.
  • Stair-step cracks along mortar joints are the usual settlement pattern, most often at corners and beside openings.(HUD)
  • Vertical cracks in the middle of a block wall are usually shrinkage.(HUD)
  • Horizontal cracks or a bulge (bowing) in brick or block mean the wall is bent or broken. HUD calls them potentially serious. Causes include poor backfilling, heavy vehicles nearby, and wet soil swelling or heaving with frost.(HUD)
  • Clean or dirty. A clean crack suggests recent movement; a dirty or previously filled one may be inactive. Watching it over time is how you tell.(HUD)
  • Seasonal cracks open and close. HUD says seal them with a flexible sealant; mortar holds them open and makes more cracks.(HUD)

No official source sets a crack width that means "call someone," so we don't give one. HUD notes the same width means different things in a new house and a 50-year-old one.(HUD)

When to Call a Structural Engineer

  • HUD: with masonry problems, hire a structural engineer, and a soils engineer too if settlement is the cause.(HUD)
  • Large uneven settlement, especially between the walls and interior columns, is more serious because it moves beams, joists and floors.(HUD)
  • Repairs HUD names for horizontal cracking: jacking the wall back with interior buttresses or epoxy grout, or lowering the outside grade to cut soil pressure. For continuing movement, underpinning.(HUD)
  • In Wisconsin no one may practice engineering without being registered. Check a professional engineer on the state's LicensE lookup.(Wis. Stat. 443.02)(DSPS)
  • For the contractor doing the repair, here's how to check a contractor's Dwelling Contractor credential. For a new sump or drain line, how to check a plumber's license.

Wet Basements

House Downspout extension Ground falls at least 1/2 inch per foot for at least 10 feet (new homes, SPS 321)
Our diagram. Wisconsin's code sets the slope for new homes; HUD, NPS and Madison all start with grading and downspouts.
  1. Start outside. HUD says most wet basements come from poor site drainage. Ground should slope away on all sides and downspouts should carry water away.(HUD) For new homes Wisconsin's code requires the ground to fall at least 1/2 inch per foot for 10 feet.(SPS 321)
  2. Check the simple things. A clogged gutter, window wells, outdoor faucets, settled backfill, or raised planting beds that hold water against the wall.(HUD) A 1-inch rain puts 1,250 gallons on the roof of a 2,000 square foot house.(City of Madison)
  3. Test the wall. Tape foil to it for a day or two. Moisture behind the foil means water through the wall; moisture on top means humid air condensing.(National Park Service)
  4. Then drainage. Madison's order: fix grading, gutters and downspouts first, then add a drainage or sump system if you still need it.(City of Madison) NPS puts excavation, coatings and footing drains last.(National Park Service)
  5. Don't seal it in. NPS warns that interior waterproof coatings on an old wall push the damp higher up the wall.(National Park Service) DOE says deal with moisture before insulating a basement.(DOE Building America)
  6. Keep the air dry. Madison recommends 40 to 50% basement humidity; at 60% it will likely smell musty.(City of Madison) EPA says dry wet areas within 24 to 48 hours to prevent mold.(EPA)

Sump pumps in Madison need a building permit, and the water can't go into the sanitary sewer or floor drains.(City of Madison)(City of Madison) Discharge somewhere that doesn't slope back to the house. A curb or storm sewer connection needs a right-of-way permit and a city-prequalified contractor.(City of Madison)(City of Madison)

White Powder and Tide Lines

  • Efflorescence is salt left on the surface when water evaporates from masonry. It's usually harmless on the surface, but salt crystallizing inside brick can spall the face.(National Park Service) HUD lists it as a sign of water getting in.(HUD)
  • Rising damp usually shows as a white tide mark 1 to 3 feet above grade that moves with the seasons. The fix is less water against the masonry.(National Park Service)

Code and Permits

  • Statewide, the Uniform Dwelling Code doesn't apply to repairs or maintenance, but its definition of repair covers only nonstructural work. Towns may require permits beyond it.(SPS 320)
  • Madison: owner-occupants can apply online for basement drainage systems without structural repairs. Structural reinforcement or replacing footings needs plan review.(City of Madison) Madison's permit chart has no separate foundation-repair row, so call Building Inspection, 608-266-4551, before bracing a wall.(City of Madison)
  • New footings must be at least 48 inches deep or below frost, whichever is deeper.(SPS 321) Remodel permits by town covers the rest.

Radon

Radon enters through cracks in floors and walls, construction joints and gaps around pipes, and EPA doesn't recommend sealing cracks alone to lower it.(EPA)(EPA) Wisconsin DHS says retest after foundation work.(Wisconsin DHS) See radon testing and $10 kits.

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Questions

Is a stone foundation bad?

Not by itself. HUD's rehab guide says older, softer lime mortar may need repointing but can still be part of a sound wall. The usual problems are washed-out mortar from too much water and repairs made with mortar harder than the stone.

When should I call a structural engineer about a basement wall?

HUD says to hire one when there are masonry problems, especially horizontal cracking or bowing in a brick or block wall, which it calls potentially serious. Uneven settlement that moves floors, beams or columns also needs an engineer. In Wisconsin an engineer must be licensed by DSPS.

Why is my basement wall white and powdery?

That's efflorescence: salt left behind when water evaporates from masonry. It's a sign water is moving through the wall. A white tide line 1 to 3 feet up that moves with the seasons is usually rising damp.

Do I need a permit to fix my foundation in Madison?

Madison owner-occupants can apply online for basement drainage systems without structural repairs. Structural reinforcement or new footings need a permit with plan review, and a sump pump needs a building permit. Call Building Inspection at 608-266-4551 to confirm for your job.