Amplifications and Clarifications
The Word really means what appears at the end of every column about not residing on Mt. Olympus and about welcoming other viewpoints. The Word is not all-knowing, as the Technical Review Committee will no doubt confirm. If comments or questions are presented in real time, The Word may sound a little flustered, as The Word needs time to think about things. Comments and questions are always welcome, however, and when clarification is needed, it will be issued, which leads us to this column.
Remember when reading all The Word columns that we're discussing general principles. Something you see in the field isn't always wrong just because it doesn't comply with a general principle. Local building codes, manufacturer's instructions and engineered designs trump general principles.
Columns below grade
The illustration in the bottom left corner of Page 20 in the September 2011 Reporter (repeated below) shows wood deck support columns installed below grade. The other viewpoint posed to The Word is that wood columns below grade are a reportable deficiency. While most of us would agree that it is usually not best practice to place wood columns below grade, doing so is not a reportable deficiency, assuming that the proper material is used and that the proper procedures are followed. In fact, placing wood columns below grade may be the only cost-effective option on steep grades and where the footings must be deep to get them below the freezing depth.
The proper material for wood columns embedded in concrete or installed below grade is preservative-treated wood that is suitable for ground contact. Some sizes and species of wood are not suitable for ground contact. For example, a 2x4 may not be suitable for ground contact even if it is preservative-treated. Naturally decay-resistant wood such as redwood is not suitable for ground contact. Wood that is not suitable for ground contact may not be embedded in concrete or installed on or below grade.
Proper procedures start with not placing an untreated cut end of a wood column in concrete or below grade. If placed in concrete, below grade, or any other exposed area for that matter, any cut untreated wood should be field-treated with a preservative equal to the original treatment. Care to guess how many framers field-treat cuts in preservative-treated wood? You probably have better odds of winning the lottery.
Proper procedures continue with securing the columns to the footing to restrict lateral movement of the column. The illustration in the September 2011 Reporter shows the below-grade columns secured using manufactured metal attachment hardware. The Word relied on Figure 12 in the American Wood Council deck construction guide DCA-6 (awc.org/codes/dcaindex.html) that shows installation of metal hardware below grade. The Word did not think through the implications of installing metal hardware below grade. A little thought (about the obvious) and a call to Simpson Strong-Tie® confirms that any type of metal hardware or fasteners should not be installed below grade. Figure 12 in DCA-6 appears misleading on this point.
The Word's revised illustration shows the columns embedded in a concrete footing. This is the only method that The Word knows of to restrict lateral movement of the columns without using metal attachment hardware.
Columns above grade
Did you know that it's sometimes permissible to install untreated wood columns? The Word isn't sure it's a good idea in most places, except perhaps in Phoenix where it rarely rains.
One exception allows untreated columns located in basements and untreated columns that are exposed to weather under two conditions. One condition is if the columns are supported by concrete piers or metal pedestals that project at least 1 inch above a concrete floor. The other related condition allows these columns if they project at least 6 inches above earth that is covered by a moisture barrier such as 6 mil polyethylene.
Another exception allows untreated columns located in crawl spaces if the columns are supported by concrete piers or metal pedestals that project at least 8 inches above earth that is covered by a moisture barrier.
Metal columns may also be used to support decks and other structures. Such columns should have a shop-applied, rust-resistant coating both inside and outside.
There is one other obscure exception that allows untreated wood columns. This involves columns that are completely and continuously submerged in fresh water. So, put on your mask and flippers and check out these columns in lakes and rivers.
The bottom line
As The Word approaches 60, he finds that his X-ray vision isn't what it used to be. Some clients, however, seem to expect a fully functioning super inspector. Without X-ray vision, we have no way of knowing the condition of any column and footing below grade whether it's for a deck or for a home. As we now know, a treated wood column below grade isn't a deficiency per se. So, what do you report?
When in doubt, The Word recommends disclosure. You should report that you can't determine the condition of any column and footing below grade or embedded in concrete. You may wish to recommend that your clients should, at least, monitor the column's condition. If the clients wish additional assurances, they can hire a qualified contractor to dig down to the footing to determine the column and footing condition. That seems a bit extreme, but it's their money.
The Word thanks Nick Boekenoogen, Liberty Inspection Services, in Scottsdale, Ariz., for offering the other viewpoint that is the inspiration for this column.
Memo to the deck gods: The Word does not reside on Mt. Olympus (just at its base and sometimes not even there) and welcomes (really) other viewpoints. Send your lightning bolts or emails to firstname.lastname@example.org. The thoughts contained herein are those of The Word. They are not ASHI standards or policies.
Bruce Barker, Dream Home Consultants, Peoria, Ariz., has been building and inspecting homes since 1987. He is the author of "Everybody's Building Code" and currently serves as chair of the ASHI Standards Committee. To read more of Barker's articles or if you need a presenter at your next chapter event, go to www.dreamhomeconsultants.com.