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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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Want to learn more about inspecting
manufactured/mobile homes? 
Get our  Handbook for 
Manufactured Home Inspectors 
at for $19.95

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Here’s links to a collection of our blog posts about MOBILE/MANUFACTURED HOMES:

• What happens when a mobile home foundation fails in a hurricane?

• Can a mobile home permanent foundation be concrete blocks on pads and screw-in anchors?

 • Does the building code apply to mobile homes? 

What is a foundation certification inspection for a mobile/manufactured home?

How do I determine the age of a very old mobile home?

What is a "HUD label verification letter" for a mobile/manufactured home?  

How do I find out how old a mobile home is and who manufactured it?

What is the right price for a used mobile home?

When did a ground cover vapor barrier (plastic sheet) become required under a mobile/manufactured home? 

Is it safe to go under a mobile home? 

Are older mobile homes unsafe? 

What do I need to know about buying a foreclosed mobile home? 

Does it make sense to buy an older mobile home and remodel it? 

Where do I find the vehicle identification number (VIN) on a mobile home? 

How energy efficient is a mobile home?

When were the first double-wide mobile homes manufactured?

Can you put a zone 1 mobile home in Florida?

How can I remove water under my mobile home?

What's the differences between a trailer, a mobile home, a manufactured home, and a modular home? 

What is a D-sticker mobile home? 

What are the tie-down requirements for a mobile home?

How fireproof is a mobile home?  

Can I install a mobile home myself?

What is a Park Model mobile home?  

Does an addition to a mobile home have to comply with the HUD Code? 

How can I tell the difference between a manufactured home and a modular home?

       Visit our MOBILE/MANUFACTURED HOMES  page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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