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Evaluating the Condition of the Basement in Your Historic Building | Wisconsin Historical Society

Guide or Instruction

Evaluating the Condition of the Basement in Your Historic House or Building

Evaluating the Condition of the Basement in Your Historic Building | Wisconsin Historical Society

Planning a historic house or building rehabilitation project is a complex process, so you might want to hire professionals to plan your project. But even if you intend to hire others to plan your project, you should understand the existing conditions of your house or building. The process of visually evaluating the condition of your basement will help you be an informed consumer. It will also show the professionals you hire that you are knowledgeable about your own building.

Gather Your Tools and Supplies

To properly evaluate the condition of your basement, you'll need the following tools and supplies:

  • Notebook or a small hand held tape/digital recorder to document what you see
  • Camera with a zoom feature for close-ups
  • Flathead screw driver, awl or ice pick for poking into old wood and other materials
  • Flashlight to see in dimly lit areas
  • Pocket knife for scraping away dirt and paint
  • Small magnet to determine whether metals are steel, lead, copper or brass

Conduct a Visual Assessment

To conduct a complete visual assessment, you must look over every part of your basement. Take good notes and photos of every part of the basement and its condition.

EnlargeBuilding interior

Milwaukee County. The white substance on the wall surface is called efflorescence and is evidence of moisture within the wall. The white coloring seen at the wood joist ends is called white rot (wood is absorbing moisture from the wall.) Source: WHS - State Historic Preservation Office.

1. Inspect structural wood elements. Begin your inspection in the interior of your basement or crawl space. Use a flashlight to look at the end of each floor joist (a beam that supports the floor above), which rest on top of the foundation wall. The ends of the joists are prone to water and insect damage. Note any joist end that shows sign of rot or deterioration. Look at every joist from one side of the foundation to the opposite side. Note whether there are vertical or horizontal cracks in the joists or if they are sagging. If an area looks suspicious, push a screwdriver, awl or ice pick into the wood. If your tool penetrates more than 1/8 to ¼ inch, it may be a sign of rot, and will require further investigation. Another simple test is to knock on the wood. Solid wood will produce a thump sound that resonates throughout the wood, while rotten wood produces a deadpan sound.

2. Inspect your masonry. Look for bricks, stones and mortar joints that are missing or deteriorated. Pay special attention to cracks in the masonry foundation walls. Cracks that follow mortar joints could result from foundation settling, while cracks through bricks or stones might indicate a structural problem that requires additional investigation by a professional. Look down the sides, back and front of your foundation walls to determine if the walls seem straight. If they appear to be bowing in or out, make a note of this. Inspect the vertical masonry or wooden support pillars in the interior of your basement for deterioration or rot at the top and bottom. If the basement floor is concrete, look for signs of settling or cracks in the floor.

Enlargeknob and tube wiring

La Crosse County. Most insurance companies will not insure buildings with knob and tube wiring. Source: WHS - State Historic Preservation Office.

3. Inspect your electrical system. Find the electrical service breaker panel or panels. Many historic commercial buildings have more than one panel, especially if the building has more than one tenant. Most often these panels are in the basement, but sometimes each tenant's panel will be on the level the tenant occupies.

  • Open the door of the panel or panels and look for the amperage of the main shutoff. The amperage should be on the nose of the shutoff. Most commercial buildings need at least 200 amps per tenant. Observe the electrical wires running throughout the basement to the breaker panel. Note whether they are neatly arranged or haphazardly installed. Determine if the wires are encased in metal or polyvinyl chloride (PVC) piping (called conduit) or running through holes in the joists. You might see illegal wires stapled to the bottom edge of the joists or just loosely hanging down. Any haphazardly installed wiring is a sign that rewiring is needed.
  • Look for antique wiring known as knob and tube wiring. Knob and tube wiring will have to be replaced, so make a note if it exists in your basement. This type of wiring has no grounding wire and can be a fire hazard. Knob and tube wiring has two wires running parallel to each other through a hole in the joist. A porcelain tube inserted into the hole keeps the wire from touching the wood. When these wires make a turn, they are wrapped around porcelain knobs nailed to the side of the joist. You might find inactive knob and tube wiring that was abandoned when new wiring was installed, but the wiring could still be live.

CAUTION:  If you find knob and tube wiring, do not touch it. If it is live, it can be a shock hazard. Contact a qualified electrician to verify if the old knob and tube wires are active or dead.

4. Inspect your main water service pipe. You can find your main water service pipe running to your house or building from the street or alley at the front or rear of your basement. This pipe might enter your building through the foundation wall or up from the floor. The pipe will have a main shut-off valve and sometimes a water meter.

Test the pipe with a magnet to determine if you have an older main water service pipe that might need to be replaced. If the magnet sticks to the pipe, it is made of either steel or iron. If the magnet does not stick to the pipe, you probably have a newer copper service line that might provide adequate service to your building. Some very early water service pipes were made from lead. A magnet will not stick to lead either. Use your pocket knife blade to lightly scrape the surface of the pipe. If it is copper, it will have a shiny orange appearance. If it is lead, it will scratch easily and have a shiny, silvery appearance. If you have a lead water service line, it will need to be replaced.

5. Inspect your visible water lines. Secondary water lines run from the main water service shut-off into your basement. Your basement may contain a variety of water pipes. You can use the magnet test on these metal pipes in the same way as the main water service pipe. Look for obvious signs of leakage along the water lines and at the joints connecting the pipes.

You may have rigid PVC water lines or flexible cross-linked polyethylene (PEX) water lines that are made with two different plastic materials. PVC is generally off-white or bone colored, and all the joints are obviously glued. PEX water lines have fewer joints, are not glued and are usually white in color for cold water and red for hot water. Each PEX joint has two steel bands crimped around the joint.

PVC water lines are not a high-quality or lasting product and should be replaced. PEX, on the other hand, is one of the most versatile water line materials available for historic structures in Wisconsin. 

6. Inspect your water heater. Your water heater should have a pressure relief valve (PRV) on its side but close to the top. A pipe exits the PRV and runs down the side of the water heater to within three inches of the floor. If pressure builds up inside the tank, the PRV lets the pressure out so the tank does not explode. If the pipe looks corroded or there is a lot of water staining on your basement floor, the PRV valve is likely in poor condition.

If your water heater is electric, it will not have a flue vent pipe coming off the top. Natural gas water heaters that are high efficiency will vent out the basement wall horizontally to the outside. Less-efficient water heaters vent into chimneys. Look where the metal flue vent pipe joins the chimney to determine if it connects to another metal flue pipe that lines the inside of the chimney. Look for rust holes or deterioration at the joints of the metal flue vent pipe.

If your building has tenants, you may have several water heaters in the basement or one on each tenant's floor level. Water heaters usually have a lifespan of 12 to 20 years, depending on the mineral content of your local water supply. A high mineral content will cause your older water heater tank to be filled with mineral deposits and operate inefficiently.

7. Inspect your drain, waste and vent lines (DWV). DWV lines carry wastewater and sewer gasses away from your kitchen, bathrooms, laundry area and floor drains. The wastewater is discharged to the city sewer lines in the street or alley. The sewer gasses are vented out through the roof. Your main vent stack pipe will start at the basement floor and continue up through the roof of your building. It will be either black cast iron or white plastic PVC. Some buildings will have black plastic, acrylonitrile-butadiene-styrene (ABS) main vent stack pipes, or even copper. Look for splits in the sides of your main vent stack pipe or signs of water staining at the joints of the pipe. Cast iron main vent stack pipes that are 60 to 100 years old are usually in need of replacement due to corrosion and rust.

8. Inspect your heating, ventilation and air conditioning (HVAC) equipment. Observe any HVAC equipment that is located in your basement. Commercial buildings will often have either a steam or hot water boiler that provides heat to cast-iron radiators throughout your building. Usually the larger your boiler, the older and more inefficient it is. Look around the boiler to see if there are water stains on the floor from leaking water. Also look for tags attached to your boiler that can tell you how often the boiler has been maintained by a local HVAC company.

If your commercial building has several tenants, it may have been converted to a forced-air heating and air conditioning system. Forced-air systems have ductwork that delivers the hot and cool air to vents in individual rooms. A set of return air vents moves air from the rooms back to the furnace. Note whether these ducts are metal or flexible plastic.

  • EnlargeMechanical ducts

    Asbestos wrap can be hazardous if un-encapsulated. When mechanical ducts with asbestos wrap require removal, the building owner will need to hire an abatement company to safely remove and dispose of this hazardous material.

    If your ductwork is metal, check to see if it is wrapped with insulation. Sometimes the joints of older ductwork are wrapped with a white tape that is usually made of asbestos. Asbestos tape can be encapsulated with special tapes that wrap around the old asbestos tape, but encapsulating asbestos tape should only be handled by a licensed and experienced asbestos abatement contractor. Encapsulating this asbestos tape will prevent loose fibers from floating into the air and causing health problems.  
  • If central air conditioning was installed with your furnace, you will see a square metal box with a fan inside the metal box. This is a central air conditioning compressor. It will be located either outside on the ground or on the roof. Count the number of furnaces and air conditioning compressors.
  • If your forced-air furnace is electric, it will not have a flue vent pipe emerging from the top. Natural gas furnaces can be high-efficiency models that vent out the basement wall horizontally to the outside. Less-efficient furnaces vent into chimneys. Look where the metal flue vent pipe joins the chimney to determine if it connects to a metal flue vent pipe that lines the inside of the chimney. Look for rust holes or deterioration at the joints of the metal flue vent pipe.

The information presented here is not intended to provide comprehensive technical advice or instructions on solving historic preservation issues. Any information contained or referenced is meant to provide a basic understanding of historic preservation practices. Read full disclaimer.