Pre-Inspection Checklist for the Interior

This is a follow-up to last week's post, which gave a home inspection checklist for the exterior of homes.  The goal of this checklist is to give potential home buyers a 'heads-up' for some potentially larger defects.  This is obviously not a complete or technical list, but it covers a lot of potential problems.

Foundation Problems

Look for cracks in the foundation walls.  Generally speaking, cracks larger than 1/4" in concrete block walls and cracks larger than 1/8" in poured concrete walls are reason for concern.

Finger in crack

Cracks that are large enough to put your hand through shouldn't be cause for concern.  They're cause for repair.

Huge cracks in wall

Cracks that have been patched and have opened up again are reason for concern, as they typically indicate ongoing movement.  Horizontal cracks are more concerning than vertical cracks.

Patched horizontal cracks

Offsets in the foundation walls are cause for concern as well.  The house shown below ended up being demolished.

Huge foundation offsets

Wet Finished Basements

It's usually quite easy to figure out if a finished basement has moisture problems if you're willing to do just a little bit of digging.  Walk around the exterior of the home first, and look for any areas without good water management; for the most part, this means negative grade and missing downspout extensions.  When downspouts discharge next to the house, there's a good chance that there will be a water intrusion issue at about the same place inside the basement.

Basement water intrusion staining always starts at the base of the foundation walls.  Pay special attention to inside corners for signs of water intrusion.  Loose for stains at the baseboard trim, and stained or patched wall areas.  Look behind furniture, and look underneath carpet if possible.

The photos below shows stained wood paneling and black, wet carpet tack strips in the same place.

Stained paneling

wet tack strips

The photos below, from the same house, show black staining (mold?) at the drywall in one of the inside corners, as well as staining at the baseboard trim.

Stained baseboard trim

Wet tack strips 2

If there are in-floor ducts, try to look inside the ducts at every floor register.  If water has entered this ductwork, it's a serious problem.

Water in duct

Water in duct 2

Plumbing – Galvanized Steel Pipes

Galvanized steel water pipes were used on older houses up until about 1950.  The problem with galvanized pipes is that they rust on the inside, making the pipe diameter smaller and smaller over time.  This leads to less and less water flow at the plumbing fixtures.  Galvanized pipes are also more prone to leakage, typically at the joints.

Galvanized pipes

To test water flow at older houses, turn on the laundry sink faucet all the way and then check water flow at the other plumbing fixtures throughout the house. On houses with galvanized pipes, we'll frequently find no water flow at the second floor plumbing fixtures when performing this test.  Once it gets to that point, it's time to think about new pipes.

The photo below shows a first floor kitchen sink faucet turned on all the way; if you look carefully, you can see a few water droplets in the air.  The repair for this condition is to have a plumber replace the old galvanized steel pipes.

Minimal water flow at kitchen sink faucet

The pipe coming from the street to the house is called the supply pipe; when this pipe is galvanized, there's a good chance that water flow throughout the house will be minimal.  The fix for this is expensive; it means digging up the yard and replacing the pipe out to the street.

On older houses, check below the water meter in the basement to verify the supply pipe is something other than galvanized steel.  The photo below shows an example of a galvanized water supply pipe.

Galvanized water supply pipe

As with galvanized steel water pipes, galvanized steel drain pipes also rust on the inside.  This accumulation of rust reduces the pipe diameter and can lead to clogged drains and leaks.

Rusted steel drain


Galvanized steel plumbing vents also rust out; sometimes they may completely rust through and allow sewer gas in to the home, but the vents are typically concealed.

Rust holes in galvanized steel vent

The eventual fix for this is replacement of the old steel drains and vents with new ABS or PVC pipes.  The first drain to get clogged will always be the kitchen sink drain.  Run water down the kitchen sink for about ten minutes to make sure it drains properly.

Neglected Furnaces / Boilers

Watch out for excessive rust, debris, and especially black soot or scorching at the furnace or boiler.  These typically indicate then need for service or replacement.

Rusted boiler

Dirty Furnace

Electric Hazards

FPE Stab-Lok electric panels are a latent fire hazard.  These panels can be easily identified by a label on the panel that says "Stab-Lok".  We always recommend replacement of these panels.

Stab-Lok Panel

In houses built from 1965-1974, look for aluminum wiring, or more specifically, aluminum branch circuit conductors.  These are a larger concern that can involve expensive repairs.  It's not always possible to identify aluminum wiring without opening the electric panel, but if aluminum conductors are used with NM cables (aka 'Romex'), it will say "aluminum" right on the cable sheathing.  Look for this in the garage or basement.

Aluminum cable

Fuse panels under 100 amps are typically inadequate for today's houses.

30 amp service with two fuses

To help determine the size of the electric service, look on the door of the electric panel.  Most old fuse panels will either be 60 amp or 100 amp.

Knob & Tube wiring is an obsolete two-wire system typically found in pre-1930's homes, and is easily identified by the porcelain knobs & tubes that are used to hold and protect the wires.    When present, knob & tube wires will usually be visible in attics and unfinished basements. The photo below shows an example of exposed knob & tube wiring at the ceiling in a basement.

knobs & tubes

At best, the remaining knob and tube wiring is in good condition and most of it has been replaced.  Be aware, however, that many home insurance companies charge a premium or refuse to insure homes with knob & tube wiring, even if it's still in pristine condition.

At worst, the knob & tube wiring has been exposed to high temperatures for long periods of time, causing the insulation on the wires to fall apart, leaving exposed conductors that create a shock and fire hazard. Examples of hazardous knob & tube wires are shown below.  Yes, these wires were live at the time of the inspection.

Frayed knob & tube wires in light fixture

Frayed Knob and Tube Wires in attic

Interior Stains

Stains at the base of patio doors typically indicates water intrusion and rot.  Step on the floor next to patio doors to make sure the wood is solid.  The photo below shows major rotting at the floor by the patio door.

Rotted patio door floor

Water stains on windows are usually caused by condensation, which isn't a major concern, but stains that are caused by exterior water intrusion are a larger concern.  To help determine the difference, click this link on window stains.  The photo below comes from that post, showing an example of window staining caused by water leakage from the exterior.

window stain

Home Inspection ChecklistHopefully these items will give potential home buyers a good starting point. As mentioned last week, here's a one-page Home Inspection Checklist in pdf format that may be helpful.

Author: Reuben Saltzman, Structure Tech Home Inspections


Written By

Reuben is a second-generation home inspector with a passion for his work. He grew up remodeling homes and learning about carpentry since he was old enough to hold a hammer. Reuben grew up thinking he was going to be a school teacher because he enjoyed teaching others so much. In a sense, that’s a lot of what home inspections are about, so Reuben truly does what he loves. Sharlene has worked with Structure Tech since 2000 and Reuben has been contributing to her blog since 2008.

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