Teach Yourself Environmental Home Inspecting
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  NOTE: May Dooley passed away in March 2024. This site will remain available as a tribute to her.

Preliminary Walk-Through Inspection

Tip: A strong flash light is very useful on a walk-through.

If you are new to home ownership, you might pick up the following book or one similar: My Home - Tips for Operating Your Home by Tom Feiza – Mr. Fix-It (2007). The book of this name on Amazon is for professional inspectors and costs a lot more than the homeowner version. Check out the misterfix-it website.

Enter the home through the living areas, not through the garage. The first thing to notice is the smell.

Does the house smell musty? If so, there is mold growth somewhere. Mold gases rise, so the smell could be coming up from the basement. There could be an undiscovered plumbing leak or mold in a lower wall cavity where groundwater is seeping in. Maybe the smell is coming from a contaminated central air conditioning system, or from a musty old rug.

Do you smell fragrances from plug-in air fresheners, laundry products, cleaning products, or something else? These fragrances typically are not benign and detract from, rather than add to, indoor air quality. House-hunting clients turned down a house because of plug-in air fresheners. They read that the smell may stay in the outlets, and they didn’t want to change out the outlets.

Walk through the house, making note of things such as:

  1. The locations of past leaks, even if 20 years ago.

  2. If there is central heat and/or AC, then note where the returns are. Is there a return in the basement? Are supply vent covers (where the air comes into the room) clean-appearing or discolored? Where are the filters, what type of filter is present, and how often are they changed? Is the unit serviced annually? Has the system ever been cleaned? Was the whole system cleaned or just the ductwork? Is there metal ductwork or flexduct (tubular, flexible)? How old is the ductwork? Is there a potential for lined ductwork, and even asbestos-lined ductwork in some old houses?

  3. Are bathroom exhaust fans present? If so, check their effectiveness. If they aren’t strong enough to suck up two squares of toilet tissue, they may not be doing too much. Consider an upgrade to something like a Panasonic Whisperquiet or equivalent.

  4. Are the walls plaster or drywall (sheetrock)? Don’t know? If your home is pre-war and walls have not been renovated, the home probably has plaster walls. Tap on plaster, and it’s like tapping on brick. Tap on drywall and you should hear a hollow sound. Of course, there are variations on the theme, such as when drywall is added over plaster, or plaster board over drywall. In general, plaster walls are mold resistant and are preferred. Modern houses have drywall.

  5. Note the location of plants. If any were over-watered, did water seep into wood surfaces below? Occasionally, mold is visible growing on a plant or on a terracotta planter.

  6. Remember where the electric lines come to the house and where the meter box is. Check that beds or chairs are not on the other side of the wall from them. Smart meters may be installed for water and gas services as well as electric, so likewise check their locations.

  7. Where is the Internet modem? The base station for cordless phone? Boosters for the wireless signal? A wireless printer? Alexa?

  8. If the house has gas, where is the gas meter? Which appliances are run by gas? Do you smell anything around gas installations?

  9. What is the status of the smoke and carbon monoxide detectors? Where are they? A carbon monoxide detector should be positioned on or near the ceiling, because carbon monoxide is slightly lighter than air. Do you regularly check that they work? Tip: If there is an attached garage used for car storage, there should be a carbon monoxide detector in the room adjacent to the garage. People have lost their lives due to carbon monoxide poisoning when they forgot the car was running.

  10. Where are the fire extinguishers stored, and are they up to date?

  11. Check the dryer hose. Does it discharge to the exterior, or in a wall cavity? When was the last time it was cleaned out? When I had mine cleaned, the worker reported that it was almost sealed off with lint and was a fire hazard. Apparently the former owner had never had the vent cleaned.

  12. Are closets stuffed or do they have some air exchange? Is there any musty smell in a closet?

  13. Are there any finished below-grade spaces? Is the basement finished or unfinished? Unfinished is preferred because the risk of hidden mold is reduced. Basements used to be considered buffer zones between the house and the land, good for wine cellars and root cellars. Not all finished basements are at risk for mold behind the walls, given a variety of factors, but many are. If you want a finished basement, you may be better off finishing it yourself, using mold-resistant materials and methods.

  14. What flooring coverings are used in the basement? Carpeting is not advised on a slab. If there is wood flooring, it might have needed to be built up several inches, with a moisture barrier below. Check with a contractor. Take a quick look at unfinished wood surfaces in the basement, such as ceiling joists and subflooring and under first floor plumbing fixtures. Do you see any discolorations? In the basement, look at foundation walls where they meet the slab. Do you see signs of white mineral deposits? Darkened areas? Are they located where a downspout might discharge rainwater too close to the house, or where rainwater might pond next to a side of the house?

  15. Take a look in the attic. Do you see signs of discolorations on rafters or roof decking? Do bathroom exhausts terminate in the attic? Is there insulation over the entry to the attic? (If not, the cut-out for an attic entry panel or pull-down steps might serve as a chimney for the loss of heat in the winter.) If you have a crawlspace, how does it smell? Is there insulation between joists? Are there vents? The more modern approach to crawlspaces will be addressed later, but it involves putting insulation on the walls and making the crawlspace part of the living space, sealing off vents.

  16. Consider the garage, if attached. Garages typically have more dampness than the house. Have you stored vulnerable items (wood, paper, cardboard) in the garage? Are wood shelves protected by painting them? Do you see discolorations on the garage door or other unfinished surfaces? On the Outside Observations page we already spoke about what can be done to reduce the penetration of vehicle exhaust from the garage into the house.

Have you learned anything that you didn’t know before your walk-through? Are there any action steps that should be taken as a result of your walk-through? Have you made notes about where you should sample for mold?


  1. Getting Started with Environmental Home Inspecting
  2. Pre-purchase considerations when when looking for a new home
  3. Outside Observations of your home
  4. Preliminary Walk-through of the home (this page)


This page was last updated:
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Created: June 8, 2020
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may _at_ createyourhealthyhome.com  
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