Cabin Plans – Pier and Beam Foundation

by Andy Sheldon

in Cabin Plans

Creating a Pier and Beam Foundation from A Crawlspace Plan

In many cases a cabin might be more easily built with a pier and beam foundation rather than a perimeter footing and wall like a crawlspace or basement.  This is especially true on sloping lots or in places where a perimeter solution would not work such as rocky soil conditions.

There are two aspects of this type of foundation that make it both easy and difficult to turn a crawlspace into a pier and beam foundation.

First… The Easy Part.

The easy part is the interior bearing points.  When looking at a crawlspace plan of any depth, you are likely to find a center beam supported by piers and footings.  You can use the same footing as shown in the crawlspace plan for the new pier and beam foundation.  The same is true for the center beam.

Second… The Hard Part

The hard part is the exterior wall bearing.  The loads on the exterior wall are a combination of roof  loads, exterior wall loads and floor loads.  The floor loads are fairly constant from one locality to another, but the roof loads are not.

To properly design a pier and beam foundation to replace the exterior wall, you must determine how many pounds per lineal foot are acting on the wall.  Once you know that, then you must do either of two things:

  • Assume a beam size and then set the pier spacing that will allow that beam to work.
  • Assume a pier spacing and design a beam that will span that distance.

Either one of these options are best left to a professional who can do the design work.  Although there are some tables available, you still need to accurately determine what the loads are on the exterior beam.

For example: The loads and beam size will be different depending on whether you have a porch on that wall or not.  The extra roof load of the porch in Florida may be very little, but with an 80lb/sf snow load in Maine or in Canada, the difference would be significant.

My suggestion for turning a crawlspace design into a pier and beam design, is to seek out local professional assistance.  In the long run, it can save you money over the cost of a mistake.

As always, your comments are very valuable not only to me but to the others who drop by.




Leave a Comment