Column Footing and Loose Posts

[pdickerson]

This is a new home inspection. Home is built on a slope, and the soil is very sandy. The column footing in the first photo is not deep enough and is already starting to be undermined at the downhill side. In my area foundation footings must be 18" below grade, but I don't think that applies to post footings in the crawlspace. Anyone know if there are any other requirements that dictate minimum post footing depth?

Also, the home has a post that bears on the exposed exterior foundation footing in the crawlspace. I see this frequently, and these posts usually do not have any means of anchorage at the base. The post in this home was cut about 1/16" short, so it was loose at the base. The top of the post was secured with a 2x4 that prevented it from moving, but clearly this is not enough. Does anyone have a photo or explanation of how this type of post assembly is supposed to be installed?

[Robert J. OConnor]

Originally Posted by pdickerson

Anyone know if there are any other requirements that dictate minimum post footing depth?

Footings need to be at least 12" deep, or deeper if required for frost, per IRC R403.4.1 ... and if it's the usual ventilated crawl the interior footings would be subject to frost action.

Originally Posted by pdickerson

Also, the home has a post that bears on the exposed exterior foundation footing in the crawlspace ... Does anyone have a photo or explanation of how this type of post assembly is supposed to be installed?

You are right that the posts should not be placed on the edge of the footings. There should be pilasters installed at those post locations ... see attached diagram.

...

[David P. Valley]

Originally Posted by roconnor

Footings need to be at least 12" deep, or deeper if required for frost, per IRC R403.4.1 ... and if it's the usual ventilated crawl the interior footings would be subject to frost action.

That would be the situation here in Massachusetts. Footings eliminate settling and slippage, and help protect posts and beams from direct contact with the earth. Footings also prevent frost heave. If moist soil freezes, it will heave upwards causing an upthrust of the soil. The movement of the soil can push up on the posts and the structure attached to it. Small movements of 1/4 inch or less are acceptable but When movement of more than 1 inch occurs, there is often structural damage to the building. In order to combat this problem, footings are placed 6 inches below the frost line in my area. The frost line is the maximum depth where the ground will freeze in the winter. In Massachusetts, footings are required by code to be a minimum of 48 inches deep.