Common Construction Wisdom

There are a bunch of widely disseminated bits of construction truisms and myths out there. I hear them quite often during my inspection work. Most are oversimplifications, some contain a kernel of truth, and some are just plain wrong!

Here is a collection of some of my favorites. I would be happy to add any of your favorites to this list, just write to


  • With few exceptions, pest control requires some modification to the conducive conditions which attracted the pests in the first place. For example; untreated wood in contact with soil is an invitation for wood destroying organisms. Rat poisons and traps are unlikely to control a rat problem in an area with a lot of debris and with accessible places to build nests. "Better living through chemistry" may be part of the answer to a pest problem, but it is not likely to be the whole answer. See the Washington Toxics Coalition, a non-profit, member-based organization dedicated to protecting public health and the environment by identifying and promoting alternatives to toxic chemicals. You may also want to look in the bookstore under Healthy Home and Environment for books on pest control issues.

  • I am often called in to evaluate a leaking flat roof and consider the redesign of the roof to one with a sloped surface. To-date, I have never found such a design to be necessary or cost effective. What I have found in these leaking roofs were signs of multiple poor quality patches using a variety of roofing "goop" all of which was applied in an unprofessional manner.

    So, based upon my experience, flat roofs leak because they were improperly installed and (even more likely) poorly maintained. While it is undoubtedly true the sloped surfaces shed water more easily than flat surfaces, flat roofs built to standard practices of the trades are reliable and less expensive to build than sloped roofs. Flat roofs do require some greater maintenance than sloped roofs, but their total life cycle costs are still lower than that of sloped roofs.

    Flat roofs have some disadvantages. They are not ideal in areas of heavy snows. They are more difficult to vent. They usually don't allow for easy access to the attic area.

    It is also important to understand that most flat roofs and roofing surfaces were not built or designed as decks, i.e. walkable surfaces.