How to Inspect Mobile Home Structures - part 2, Piers, Stabilizers, Tie-downs, Multi-wide connections InspectAPedia® -
Mobile home structural inspection guide
Common mobile home structural defects: Piers, stabilizers and tie-down for mobile homes, trailers, double-wides, multi-wide connections
Safety and building codes for mobile homes, double-wides, and trailers, also some campers
How to Inspect Mobile Homes or Manufactured Housing for Structural Defects: special attention to tie-downs, hurricane and storm damage prevention, and special connections between sections of double-wide and multi-wide mobile homes.
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Ver.3.5 - 04/25/07, updated through 2011 - Steve Vermilye, New Paltz NY and Daniel Friedman, Poughkeepsie NY,
Hudson Valley ASHI Chapter Seminar, Newburgh NY, January 4, 2000, NY Metro ASHI Fall 99 Seminar, Holiday Inn Crowne Plaza, White Plains NY, October
2, 1999.
slab preferred; assure good drainage away (risk
undermined piers); (Floating or on frost footings ok)
missing or improper tie-downs against storm
damage (Northridge disaster & in FL); tie-downs may be driven or
screwed into ground; cables must be taut.
improper masonry piers-blocks on sides, stacked
debris, removed chassis, water-undermined piers; footings/piers often not
below frost line; reinforced floating slab may work ok;
piers at excessive intervals (more than 6-8 feet
and/or closer than 3 ft. to the ends of the home)
piers missing at large sidewall openings
(sliders) or at tip-outs or expanded units or under fireplaces.
masonry piers: properly-stacked blocks, hardwood
or treated wood or concrete cap, shims; piers sit on
16"x16"x4" concrete pad, pre cast or poured in place, or
12" x 20" treated wood;
Piers less than 36" high can be
single-stacked 8x8x16" block with the long 16" dimension
perpendicular to the frame;
Piers 36" to 80" high and all corner
piers of more than 3 blocks high shall be double-blocked with interlocking
alternating courses and capped with 5x16x16 solid concrete block or
equivalent;
Piers more than 80" high must be double
blocked, alternating courses, laid in mortar and steel reinforcing rods
set in block cells and cells filled with concrete.
NO more than 4" of wood in space between
pier and frame; No more than 1" thick shims and must be tight;
Metal stands (jacks) on soil surface likely to
shift/tip/settle; Steel piers should be on concrete soil pads/footings;
Settlement: may show up as hard-to-operate
windows/doors;
Our photo (left) shows sloppy pier and shim installation, set on soft soil, tipping. It is important to take a look under a mobile home or trailer you're thinking of buying. Those hard-to-get-in spots often contain costly surprises.
STABILIZING SYSTEMS - Tie Downs for Mobile Homes
Our photo at left shows that although this trailer has been placed on a concrete slab foundation, it still rests on its wheels and on temporary jack stands. No piers, no tie-downs, no permanent support was provided.
DEFINITIONS:
Stabilizing Devices: all components of the anchoring & support systems
Support System: combination of footings,
piers, caps, shims that support the home
Anchoring System: system to resist overturning
and lateral movement
Anchoring Equipment: combination of straps, cables,
turnbuckles, chains and tensioning devices.
Anchor:
device secured in the ground (Screw or other)
This mobile home frame (photo at left) has been set on dry-laid concrete blocks, with plywood shims. But the blocks rest directly on soil. This is not a reliable support system and may not be permitted by local building codes. The tie-down cables are in place but we could not find that their free end was connected to anything.
Tie down materials for mobile homes, trailers, double-wides: cable, chain, strap and tensioning device;
Diagonal
tie downs for mobile homes, or frame straps, at 45 deg. angle attach to main frame at one end
and to ground at other to resist lateral movement; Ground anchor should be
about at same angle as the strap;
Tie downs for mobile homes may be vertical;
Diagonal tie downs for
double-wide units are required only at outside rails of each unit;
Vertical straps or ground straps resist uplift and overturn, required only
for hurricane or wind zones;
The number and placement of tie downs for mobile homes and trailers depends
on the wind zone in which the home is located and the length of the structure.
For example, a 65' trailer would need 2 to 3 vertical tie downs per side, or 4 to 6 tie downs per side
if diagonal tie downs are used, depending on
which wind zone it's in.
Connection requirements for mobile home and trailer tie downs: the mobile home tie down is connected to the steel I-beam at specific locations
provided by the manufacturer; typically strap wraps around the I-beam.
Tie downs for mobile homes, trailers, double-wides are usually expected
to be placed and connected according to details provided in
the mobile home installation manual (have you ever seen one?). If you know your mobile home
or trailer model name and perhaps serial number, you may be able to contact the mobile home
manufacturer to ask for an installation manual.
Links to more detailed mobile home or trailer
tie-down installation specifications, methods, and advice can be found at Structural Advice.
MULTI-WIDE CONNECTIONS - Multi-Wide Mobile Home unit connections:
lag screws or through bolts at adjacent mate
beams, especially important if the manufacturer has support columns under
only half of the home;
hinged roof connections require that king posts
be site-installed and metal uplift straps secured to the mate lien wall
and roof assembly once the hinged roof is up;
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Additional technical contributors & reference sources for this article are listed below.
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"Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
"Modular Home Construction, special defects and inspection methods" Dan Friedman, NY Metro ASHI Seminar, Holiday Inn, Crowne Plaza, White Plains NY, October 4, 1996
New York State: "Manufactured Homes: an installation guide for the code enforcement official," undated. [Div. of Code Enforcement & Admin. - 518-474-4073, George E. Clark, Jr., Director] - this is a guide tool, not an enforcement code or standard.
HUD State Administrative Agency (for 36 states) (NY: 518-474-4073) - for complaints
Manufactured Housing Institute, 2101 Wilson Blvd. Ste. 610, Arlington VA 22201 703-558-0400 www.mfghome.org
NYMHA, 35 Commerce Ave., Albany NY 12206-2015 518-435-9859 800-721-HOME (they want the Star Program to provide for separate assessment of manufactured homes)
Consumer Reports: www.consumerreports.org - special report 2/98
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cobeen, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328
This book is an update of a long-established text dating from at least 1988 (DJF); Quoting: This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the California PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations.THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design.
Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
"Avoiding Foundation Failures," Robert Marshall, Journal of Light Construction, July, 1996 (Highly recommend this article-DF)
"A Foundation for Unstable Soils," Harris Hyman, P.E., Journal of Light Construction, May 1995
"Backfilling Basics," Buck Bartley, Journal of Light Construction, October 1994
"Inspecting Block Foundations," Donald V. Cohen, P.E., ASHI Reporter, December 1998. This article in turn cites the Fine Homebuilding article noted below.
"When Block Foundations go Bad," Fine Homebuilding, June/July 1998
Masonry structures: The Masonry House, Home Inspection of a Masonry Building & Systems, Stephen Showalter (director, actor), DVD, Quoting: Movie Guide Experienced home inspectors and new home inspectors alike are sure to learn invaluable tips in this release designed to take viewers step-by-step through the home inspection process. In addition to being the former president of the National Association of Home Inspectors (NAHI), a longstanding member of the NAHI, the American Society of Home Inspectors (ASHI), and the Environmental Standard Organization (IESO), host Stephen Showalter has performed over 8000 building inspections - including environmental assessments. Now, the founder of a national home inspection school and inspection training curriculum shares his extensive experience in the inspection industry with everyday viewers looking to learn more about the process of evaluating homes. Topics covered in this release include: evaluation of masonry walls; detection of spalling from rebar failure; inspection of air conditioning systems; grounds and landscaping; electric systems and panel; plumbing supply and distribution; plumbing fixtures; electric furnaces; appliances; evaluation of electric water heaters; and safety techniques. Jason Buchanan --Jason Buchanan, All Movie Review
Masonry Structures: Behavior and Design, Robert G. Drysdale, Ahmid A. Hamid, Lawrie R. Baker, The Masonry Society; 2nd edition (1999), ISBN-10: 1929081014, ISBN-13: 978-1929081011
Straw Bale Home Design, U.S. Department of Energy provides information on strawbale home construction - original source at http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10350
More Straw Bale Building: A Complete Guide to Designing and Building with Straw (Mother Earth News Wiser Living Series), Chris Magwood, Peter Mack, New Society Publishers (February 1, 2005), ISBN-10: 0865715181 ISBN-13: 978-0865715189 - Quoting: Straw bale houses are easy to build, affordable, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder’s personal space needs, esthetics and budget. Despite mushrooming interest in the technique, however, most straw bale books focus on “selling” the dream of straw bale building, but don’t adequately address the most critical issues faced by bale house builders. Moreover, since many developments in this field are recent, few books are completely up to date with the latest techniques. More Straw Bale Building is designed to fill this gap. A completely rewritten edition of the 20,000-copy best--selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.
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