Pier and Beam Foundation Repair / House Leveling
Pier and beam houses can be defined as structures that can be crawled under, that is, structures that have a crawl space. There are a number of foundation problems that are unique to pier and beam structures.
1. Unlike a slab foundation with concrete floors, a pier and beam structure has wood floors, and a wood sub-structure. The disadvantage of this is that the wood is susceptible to rot after prolonged contact with water or soil, and also to deterioration from termites and other critters. The solution is to prevent any ground to wood contact, and to prevent moisture contact with the wood. Once the wood is rotted, it must be replaced.
2. the next main concern of a pier and beam structure involves undersized or poorly spaced lumber. A 4” by 6” wood girder is usually the minimum size for a girder supporting the structure.
A 4” by 4” can sometimes be used, but it increases the chances of sagging, and the floor above may dip. If the supporting piers are placed closer together than the standard 6 feet apart, sometimes a 4” by 4” can be used, and a 4” by 6” can also sag if the piers are placed too far apart.
Floor joist sizes range from 6” to 12” in most pier and beams. The standard is an 8” joist, but in some houses a 12″ is used. The larger the joist, the longer the span it may reach without causing a sag or causing the above floor to shake.
Joists are usually installed on 18” centers, and girders are rarely installed further than 12 feet apart. Engineers and architects know the proper spacing, and they know the larger the girder or joist, the greater the spacing that can be allowed without sagging and dipping, depending on the amount of weight above.
In cases where poorly spaced or undersized joists or girders is recognized, more lumber can usually be added to give it strength, without the expense of replacing any lumber.
3. Poorly spaced piers are always a main concern with pier and beam foundations. The standard spacing of piers is about 6 feet apart. This rule will usually prevent sagging of the wood structure above. Also, if the pier supports do not cover enough area on the ground, they are likely to settle into the ground. If the piers rest on a base, or a concrete footing, it covers more area, and it will distribute the weight more successfully. More piers will, of course, share the weight of the structure more successfully than less piers.
4. Inadequate pier design is quite common under pier and beam homes where an inexperienced contractor has tried to install a makeshift support. The most common defective supports used are wooden stiff legs, which is a piece of wood stuck in the ground under the structure. Sometimes stacked up bricks are used, and even sticks of pipe. If the support does not cover a large area at the bottom, it is usually a poor support, and needs to be replaced. Under a pier and beam structure, depending on the weight of course, a poured in place footing about 1 foot in the ground, and about 2 feet by 2 feet, will usually support most pier and beams, if they are placed on no further than 6 foot centers. Many homeowners are concerned about bois d’arc posts, or cedar posts. These are fine if they are not seriously tilted, but it may be necessary to add other concrete footings in between them because they usually do not cover much area at the ground.
5. Usually the largest expense in repairing a pier and beam structure is when there is little or no crawlspace. Sufficient crawl space needed is usually a minimum of 18” under the floor joists, but 24” minimum is more desirable. Sufficient crawl space allows air to flow freely under the structure, keeping it dry. It also allows inspectors access under the structure, with plumbers, engineers, telephone repairmen, air conditioning installers, electricians, and our most favorite of all – – foundation contractors. If they don’t have access under the house, then they cannot inspect, install, or repair. It is time consuming, and therefore very expensive, to dig out the soil under a pier and beam. There is also the added danger of water accumulation in the area dug out. If enough area is dug out, it may also undermine the pier supports, and new pier supports must be added.
6. The next largest expense in repairing a pier and beam structure is removing crowned floors. Most dips in the floor can be removed by simply jacking the low areas up, but when the floor is crowned, the wood may be permanently bowed, and a simple jacking procedure will not take the bow out. Bedrock has been successful only by surgically cutting out the bowed lumber, and replacing it. Sometimes this can be done without cutting any of the floor above. Other procedures to remove the bows are time consuming, expensive, and will rarely reach the intended results.
7. Some pier and beam structures lack girders around the perimeter of the structure entirely. Usually only a flat sill is all that supports the structure between the pier supports and the floor joists. In these cases, the floor will be wavy and bow in many places under a properly sized girder is added.
8. Drainage problems are more severe in pier and beam structures than under slab foundations, because a concrete slab placed against the ground, with no voids under it, will block water from traveling under the structure. A pier and beam is an open channel for water to travel under the structure, causing settlement or upheaval wherever it accumulates. The water is also a haven for bugs, bacteria, molds, and algae. Standing water can also cause a musty, unhealthy smell inside the home. Call our sister company, Bedrock Drainage Corrections, LLC, if you think you have a problem with water around or under your pier and beam structure.
9. There are numerous architectural defects under pier and beam structures that can severely affect the functionality of the structure. In these cases, the designer, architect, builder, or constructed the building in a way that seriously affects its structural integrity.