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What are the most common defects in mobile/manufactured home foundation piers?
Monday, June 11, 2018
Checking The Piers Underneath A Mobile Home
When the piers under a mobile home have defects, they are due to either incorrect installation or deterioration/settlement over time. If you don’t know much about mobile home foundations and look under one, it seems incredibly basic: just stacked concrete blocks on a plastic pads. What could go possibly go wrong with something that simple? Here’s our list:
• Plastic foundation pad too small for spacing of piers along I-beam or centerline - Pad size based on calculated load at each pier.
• Concrete blocks sit on pad in wrong direction - For pads that are not square, the long side of block must be parallel to long side of pad.
• Pier blocks are not perpendicular to I-beam or centerline - Load not distributed correctly if blocks are parallel to I-beam or centerline.
• Voids in block not facing upward - Concrete block has significantly less load-bearing strength when voids are facing sideways.
• Block pier not centered on pad - Must be centered to distribute load correctly.
• Block pier not centered under I-beam - Again, important for load distribution.
• Block piers too tall - Single block piers cannot exceed 36-inches, measured from top of pad or footing to top of concrete block stack, including 4-inch cap block. Reduced to 24-inches at corners. All piers over 36-inches and corner piers over 24-inches must be double-stacked block. Piers over 52-inches must have engineering specs.
• Block piers too short - Minimum distance allowed between ground and bottom of I-beam is 18-inches except that, when the grade is sloped, 25% of the area can be lower—but not below 12-inches. This is a “Florida over-ride” that exceeds 12-inch minimum crawl space clearance under a home allowed by HUD.
• Block piers leaning - Horizontal offset from top of bottom of pier cannot exceed 1-inch.
• Blocks cracked or chipped - Fractures or otherwise damaged block not acceptable.
• Cap blocks wrong size or wrong material - Can only be approved material, such as solid (no voids) 4-inch concrete block, pressure-treated wood 2x8x16, or approved plastic caps.
• Shims incorrectly installed - Shim stack can be no more than
1-inch high under new home, or 1-1/2 inches under used home. Stack must align.
• Piers within 2-feet of centerline end walls not installed - This is another “Florida over-ride” requirement that exceeds HUD.
• Centerline piers not placed correctly under centerline openings - Per manufacturer’s specs or load calculations.
• Perimeter piers missing or not located correctly under exterior walls - Per manufacturer’s specs, such as under tile floors, kitchen cabinets, inset wall, or bathtub at marriage or sidewalls.
Although foundation piers are essentially only stacked blocks on a pad, every element must be sized, spaced, and positioned correctly for the assembly to support the home safely. A sagging or bowed I-beam, and crown in the floor near exterior walls, are examples of problems that can result from poor foundation installation.
How To File A Complaint About A Bad Installation
See our blog post Where can I file a complaint if I have problems with my new or used manufactured/mobile home in Florida? if your feel your home was installed incorrectly or has other defects.
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