Home Foundation

Wait - Your Inspector Didn't Say Anything About Anchor Bolts?

First, a little history lesson. We tend to think that modern standards are inherently superior to the ‘good old days’. That may be so, but that does not mean that an older foundation is unsafe or needs a full retrofit. Many of our old foundations (in this region) are doing just fine. Many of those do not have a single anchor bolt, either.

Washington State began requiring anchor bolts on a statewide basis in about 1973 though many of our 1950s and 1960s Pullman and Clarkston homes have them. Prior to that, the state mandated them in the Puget Sound region due to earthquake potential.

Anchor bolting is installed to handle seismic and wind forces that have the potential to knock a home off the foundation. The Northridge quake is a case in point. The manner in which we installed them changed after that quake and the design of the washers was modified to limit damage.

Anchor bolts are not always visible - finished basement will prevent access - but it pays to have your inspector making the effort to identity if they are present or not. I do so in my reports on a separate line. If they are missing, the client gets a nice explanatory paragraph.

It’s a fairly common defect to find that the anchor bolts are present but missing washers and nuts. When this happens, it becomes a repair issue. If they are not spaced correctly, it becomes a judgement call - is it worth the cost to retrofit versus the risk. On this side of the state, our earthquake risk is minimal compared to Seattle. Most people don’t retrofit, but they always appreciate the information.

Isn't the Water Supposed to Drain AWAY from the House?

The crawlspace vents are lower than the surrounding soil. It's a fairly common occurrence and easy to fix.

More often than not, your builder is not to blame - it is the landscaper who is beautifying the home without the awareness of the rest of the home systems. 

On a New House? Never! - er, Almost Never

Every municipality has what are known as design criteria for their region. These criteria include things like wind speeds, snow loads, what kind of seismic activity can be anticipated, and that sort of really useful data. 

One of these criteria is the frost depth. Also known as the frost line or freezing depth, it is the point in the soil where groundwater can reasonably be expected to freeze.

This is important to the home builder because the foundation can be damaged by frost heaves. These occur when the water freezes into ice crystals. Remember that water expands when it freezes? It is that same basic fact with the added concern that it is applying force to the foundation and can crack a foundation wall.

Older homes in our area often do not have sufficient depth on the foundations. Short of major excavation and rebuilding of the foundation, this is not correctable.

On newer houses, it should never be an issue - until it is. I ran into that recently in a house that was built after 2000. I popped the hatch, saw this -

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- and ran for my tape measure. By measuring the distance from the base of a window to the bottom of the foundation wall, both inside and out, I determined that the depth was 27 inches.

Design criteria for Whitman County is 32 inches.

Houston, we have ourselves a problem. Add in the fact that the home was two stories tall over this, and the problem compounds.

My recommendation to my client was to seek professional engineering. Not good news for them, I know, but better to know these things on the way in than six years from now.