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.  

• • • • • • • • • • • • • • • • • • • • • • • • • • • • • 

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?• Does the building code apply to mobile homes? 

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

 What are the most common defects in mobile/manufactured home foundation piers?

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. 

How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes






Air Conditioner & Furnace Age/Size




Aging in Place


Click Below  

for Links

to Collections

of Blog Posts

by Subject


Doors and Windows


Energy Efficiency

Fireplaces and Chimneys

Heating and Air Conditioning

Home Inspection

Hurricane Resistance

Electrical Receptacle Outlets

Electrical Panels

Garages and Carports

Common Problems

Exterior Walls & Structures



Life Expectancy

Mobile/Manufactured Homes

Older and

Historic Houses

Mold, Lead & Other Contaminants

Modular Homes

Metal Roofs



Pool and Spa

Roof and Attic




"Should I Buy A..."


Termites, Wood Rot

& Pests

Structure and Rooms


Water Heaters

Water Heater Age

Septic Tank Systems

Plumbing Pipes


When It First

Became Code

Park Model Homes

Shingle Roofs


Wind Mitigation Form

"Does A Home


"What Is The Difference Between..."


Concrete and

Concrete Block


Rain Gutters


Crawl Spaces

Building Permits

Clay Soil




HUD-Code for

Mobile Homes

Flat (Low Slope) Roofs

Sprinkler Systems

4-Point Inspections

Frequently Asked Questions (FAQ)

Building Codes

Inspector Licensing

& Standards

Washers and Dryers



Electrical Wiring

Plumbing Drains

and Traps

Smoke & CO Alarms

Top 5 results given instantly.

Click on magnifying glass

for all search results.



Electrical Switches


Water Intrusion

Electrical - Old

and Obsolete

Foundation Certifications