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.

Best,

Andy

 

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{ 4 comments… read them below or add one }

Jeffrey Stilwell August 31, 2013 at 5:33 pm

Hey Andy – we recently purchased your Cohutta plan and was curious if you have ever designed that model with pier and beam foundation. If so, would you be able to share that? We’re in south Texas – snow-load is a non-issue ;)

Thanks!

Reply

Andy Sheldon September 3, 2013 at 6:49 am

Jeffery… Unfortunately we have not designed a pier and beam foundation for the Cohutta. If we had, it would have been over designed for your area since snow loads are a non-issue. If you are thinking of using a pier and beam method, I would suggest looking to a local engineer or builder who would know your local conditions. Although it would be a cost, the difference between an over designed foundation and one to fit your conditions, just might be the engineer’s fee.

Best of luck with the Cohutts.

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Jim Greenfield October 30, 2012 at 9:27 pm

Andy, want to build cabins for a christian youth camp. The current cabins are not attractive. Need to bunk `12 to 18 campers. I have my own sawmill and want a post and beam plan design that can look attractive and functional. Do you have such a plan?

Reply

Andy Sheldon October 31, 2012 at 1:10 pm

Hi Jim: You might want to look at the Saphire Cabin Plan (#C-582). Just build the shell with no loft. It is a 20ft x 20ft timber framed plan. On each side, you could easily get 4 bunk beds for a total of 16 campers. Another design would be the Wilderness Cabin #Cw-192. It is 12ft x 16ft. Build two next to each other for a 12ft x 32ft cabin. You could easily get 6 bunks (12 campers) or maybe 7 bunks (14 campers). This would not be a timber framed design, but you could easily make it one. You can Download Our Catalog Here.

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