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What is Post and Pier Construction?

Post and pier construction can be found in tropical and flood-prone regions.
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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 20 September 2014
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Post and pier construction is a technique used to build the foundations of a house quickly and cheaply. This type of construction is characterized by lack of a perimeter foundation or foundation pad. It is often employed in the tropics and in flood-prone regions, for reasons which will become apparent shortly, and it is also commonly used in low-cost construction.

In some regions, these foundations are not permitted, due to concerns about safety. New homes must be constructed using a different foundation method, and older homes may require retrofitting to be sold or insured. In other regions, this construction technique is perfectly acceptable, and sometimes even preferred.

In post and pier construction, the weight of a home is distributed across a series of posts installed under the home and mounted to piers, which are wedge-shaped concrete blocks that distribute the weight across the ground. Typically, posts and piers are mounted all the way around the perimeter, and at key points in the middle of the home to ensure that the floors, and the rest of the house, do not sag.

Obviously, a home which has been built using this construction method does not have a basement, because the house is elevated. It is not uncommon to use cladding or facing between the ground and the floor of the home so that the underside of the house is not exposed, although in some regions, this area is left open.

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In areas where flooding is common, post and pier construction can significantly reduce flood damage, as the house is lifted above the water. Areas prone to subsidence can also be suitable for this construction method, as a perimeter or slab foundation would crack, whereas individual posts and piers can be jacked up and replaced as needed. It also tends to keep insects out and reduces mold, mildew, and rot, because it promotes air circulation under the house and lifts the house out of range of insect pests.

The danger of post and pier construction is that, if posts or piers start to fail, it can be very dangerous. In perimeter and slab foundations, the weight is distributed very evenly, so a partial failure or crack is an issue, but not an immediate safety problem. In post and pier homes, the weight is concentrated on the individual spots, so if something breaks, rots, or shifts, that area of the house may start to sag. In extreme cases, a house may even crack open as the weight shifts across the remaining posts and piers.

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Discuss this Article

anon944037
Post 5

It's difficult (impossible?) to get a conventional mortgage for a home with this kind of foundation in Portland Oregon.

We've got a history of earthquakes, and pier and post foundations don't fare well when stressed by seismic activity, but I don't know if this is the salient or sole reason the foundations are viewed as a liability.

anon281363
Post 4

What does this kind of foundation do for the mold that you frequently see near the floors of a home? Would it make much of a difference? I have had to deal with a lot of mold removal in my life, and I wouldn't mind having a way to prevent that at least to some degree. Now would be the time to do this as well considering the fact that I'm in the process of moving and possibly building my own home.

anon108630
Post 3

For insurance purposes, what does an underwriter needs to look for? Do you know any insurance company who will insure this type of house in BC?

pretendblond
Post 2

I recently bought a house with an "other room" that turns out to be an enclosed carport. I want to make this room actual living space and raise it to the level of the 1st floor. Could I use a post/pier foundation to support this room only. BTW it's a 16'x15' area. Any insight would be greatly appreciated!

macdamit
Post 1

Once a post fails, what can be done to fix it or repair or replace it. I have one that has started to sink. approx 6 inches already.

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