Unearth the No. 1 Cause of Structural Failures

Unearth the No. 1 Cause of Structural Failures

by Walt Keaveny, MS, PE, PG, Risk Manager, 2-10 Home Buyers Warranty

What is the leading cause of residential structural failures? Did you guess expansive soils? Sof t organic soils? Improper drainage? How about inadequate engineering design? Low-strength concrete? Poor framing practices? Nope, none of those. What may surprise you is that the leading cause of structural failures is avoidable. Warnings to avoid this significant construction liability are found in project specifications, common codes, and industry standards. What then is this real hazard that is misunderstood and overlooked? Improperly compacted structural fill material.

2-10 Home Buyers Warranty (2-10 HBW) is the national leader in new home structural warranties, who has nearly 40 years of forensic analytics and investigations that concludes fill material is the leading cause of residential structural failures. These failures can occur anywhere that existing or new fill material is used to support a foundation. Since 80% of all structural failures are due to soil movement beneath the foundation, proper use of structural fill is every bit as critical as determining building location, selecting trade partners, and a sellable home design.

Structural fill material must be of sufficient quality and density, or else it can consolidate, causing excessive settlement. This may result in damage to foundations, framing, and interior finishes. Structural distress resulting from improper fill is likely to begin soon after construction is completed. Due to common over-irrigation of the new landscaping and concentrated roof drainage, the fill quickly consolidates under the new foundation load and it is saturated and further weakened. Less than a one foot thickness of improper fill may cause serious distress. The damage caused by fill is typically more severe and costly to repair than other causes of structural failures. This is because the entire foundation is commonly underlain by fill. The average cost to investigate and repair a qualifying fill claim is about $50,000. This does not include the cost of the home builder’s reputation for quality construction practices.

To avoid structural failures caused by fill material, builders should confirm that prospective land to be developed with “existing” fill was properly compacted and tested. Developers typically sell land “as-is”, leaving the home builder liable for any existing fill. “New” structural fill to be placed by the home builder should be properly compacted and tested to verify the density. This is an industry standard practice, and a requirement of the local, state, and International Building Codes (IBC), the building department, plans and specifications, geotechnical engineer, and Department of Housing and Urban Development (HUD).

HUD’s requirements are specified in their Data Sheet 79G Land Development with Controlled Earthwork which states, “For any development in which buildings are to be placed on graded areas, all earthwork shall be designed, engineered, and constructed in such a manner that there will be no adverse differential movement which may cause damage to the structure…” HUD further specifies that, “Field density tests shall be made by the Soils Engineer…” Structural fill material should be placed in relatively thin lifts at, or near, optimum moisture content. Just the right amount of moisture lubricates the fill which allows it to achieve optimum density. Optimum moisture and density for a particular fill are determined using a Proctor test in a soils laboratory. Each lif t should be properly compacted. It is important to note that the weight of the bull dozer or front-end loader used to place the fill is typically not sufficient to compact the fill. Dozers and loaders spread their weight over wide tracks, or tires, to avoid getting stuck, and are not designed to impart sufficient compactive effort like a true soil compactor. Density testing, conducted by a representative of the geotechnical engineer, should be used to confirm and document if proper compaction has been achieved to protect the home builder’s liability.

Home builders can rely on the expertise of a geotechnical engineer, as needed, in order to identify existing undocumented fill, specif y proper cut and fill methods, specify fill quality and compaction criteria, identify onsite and offsite fill sources, and test for proper fill density. The engineer can also assist the home builder to avoid other common problems associated with improperly compacted fill, such as slope failures, retaining wall failures, and drainage problems.

In summary, diligent practices regarding structural fill material include:

  1. Check prospective land for existing undocumented fill
  2. Check fill quality and use proper fill placement methods
  3. Use the proper equipment for fill compaction
  4. Test and document fill density
  5. Utilize a geotechnical engineer as needed

Structural failures caused by fill material are avoidable. Proper fill placement will help protect a home builder’s liability and hard-earned reputation.

Top 10 Significant Modifications to the 2018 IRC

Last week the S.C. Building Codes Council met to review dozens of proposed changes to the International Series of building codes, including the International Residential Code, the building code that applies to one- and two-family dwellings in South Carolina.

Your Home Builders Association, working with your Home Builders Association of South Carolina, proposed several modifications, including one that would have removed Arc-Fault Circuit Interrupters from the building code.

Below is a list of the top 10 significant changes and modifications to the 2018 IRC.  These changes, as well as dozens of others, will be presented to the General Assembly in January.  The effective date of the new building code is expected to be January 1, 2020.

  1. Sections 301.2 and 301.2.2.1-Wind & Seismic Maps. The HBA of SC supported a study to be funded by the S. C. General Assembly and produced by The Citadel to review and address the probabilistic hazard maps. This will ensure that houses in S. C. are built on the needs and hazards of our state. 
  2. Section 301.2.1.2 Protection of openings. This change replaces 2-story limit on use of wood structural panels for wind-borne debris protection with limit based on 45-foot mean roof height. 
  3. Section 302.1 Exterior Walls. This modification maintained the minimum fire separation distance for improvements constructed on a lot where the local governing authority has prior to the implementation of IRC 2012. 
  4. Section 302.5.1 Opening Protection. The existing modification was maintained to remove the use of a selfclosing device. 
  5. Section 313 One-and -Two Family Dwellings Automatic Fire Systems. This modification maintains that residential fire sprinklers continue to be an option, but are not mandated. 
  6. Section R318.1 Protection Against Subterranean Termites. This modification adds an additional method to allow treatments to be conducted under the S.C. Pesticide Control Act and enforced by the Clemson University Department of Pesticide Regulation. 
  7. Section R318.4 Foam Plastic Protection. This modification adds language to allow foam plastics to provide an inspection gap for crawlspace applications. 
  8. Section M1502.4.2 Duct Installation. Language would allow exhaust ducts to be supported at intervals not to exceed 8 feet and ducts will no longer be required to be joined with screws. 
  9. Appendix Q Tiny Houses. By adding Appendix Q builders will have more options and flexibility for small home construction. 
  10. Section E3902.16 Arc-Fault Circuit Interrupter Protection. Language rolls back code to earlier version that would remove the use of AFCIs in kitchens and laundry rooms.

Be sure to thank these members, who have served on your HBA’s Building Codes Committee and have actively support the work of reviewing and modifying the new building code:

  • Matt Shouse, APB, Chairman
  • Mike Freeman, APB, member of the NAHB Building Codes and Standards Committee
  • Joe Hoover, APB
  • Matt Ruth, APB
  • Rick Quinn, APB
  • Steve Carson, APB
  • James Speer, APB
  • Lee Hornbeck, APB

Building Codes Class for the New Code, Effective July 1

The S.C. General Assembly has signed off on a new Residential Building Code for South Carolina, the 2015 IRC. It takes effect on July 1, 2016!

Your HBA held a Building Codes Class on this new building code in February, so many of you are already prepared. For those of you who are not, below are opportunities we are developing in the next couple of months to get you ready:

  • John McLeod, Chief Building Official for Greenville County, will host a workshop on the new codes on Tuesday, June 28, 9 a.m. until 11 a.m., in Conference Room D, Greenville County Square. He will review and highlight the important code changes and of course offer his enforcement interpretations.
  • Your HBA is working with John and Buddy Skinner, Chief Building Official for the City of Greenville, on a second opportunity in early July. 
  •  And your HBA will also have Andy Barber, HBA of South Carolina Building Codes Chairman, back in Greenville in early August for a repeat of the four-hour code training class he offered in February.
Note that the new building code is effective for permits issued on or after July 1. Houses already permitted or for which a permit was applied for on or before June 30 will still be subject to the 2012 IRC.

Note, however, that you may find that several of the statewide code amendments that were secured by your Home Builders Association make the new code an improvement in many respects. You can review the statewide amendments by clicking here.

Code Books Available Through Your HBA

Your HBA can help you receive the ICC member discount on code books, thanks to Buddy Skinner who has offered to place the order for us. If you would like to order your code book in this manner, please review the code book options at iccsafe.org and email your code book requests to mdey@hbaofgreenville.com. Your order is due by June 28 at 5 p.m. Plan on a week for the code books to be delivered.

2015 Building Codes Adoption

The list of modifications to the 2015 editions of the International Code series has completed the legislative process as required by law. The projected date for implementation is July 1, 2016. Any projects that have permit approval prior to July 1, 2016 may be completed using the 2012 series. I want to thank the members of the HBA Building Codes Committee for their hard work to modify the code. Their work has allowed a much more manageable code to be implemented in S.C.

List of the modifications to the 2015 Building Codes

New Requirements Announced for Federally Insured Construction

New energy-efficiency requirements as part of the Energy Independence and Security Act of 2007 go into effect this summer for new single- and multifamily homes insured through or with financing provided by some federal housing programs.

All homes using the programs must meet the requirements of either the 2009 International Energy Conservation Code or ASHRAE 90.1 Standard for energy efficiency.

Because the requirements are keyed to updates in the model building codes, the departments of Housing and Urban Development and Agriculture – the two agencies that administer the affected programs – estimate that the new standards will affect about 3,200 multifamily and 15,000 single-family units per year.

That is because the new rules only affect homes built in jurisdictions that have not yet adopted the 2009 International Energy Conservation Code for single-family or low-rise multifamily (three stories or less) or the 2007 ASHRAE 90.1 standard for mid- and high-rise multifamily construction.

South Carolina has adopted the 2009 IECC.

The Department of Energy says that only 12 states have building codes not meeting the requirements, although some jurisdictions within those states may already exceed them.

Excluded are homes built under HUD’s Housing Choice Voucher Program, Indian Housing Programs, Community Development Block Grant Funds, or USDA multifamily housing programs.

HUD and USDA also will accept certain programs and properties as being in compliance if they meet equivalent or higher energy-efficiency standards. This includes homes built under the Public Housing Capital Fund, Section 811 Supportive Housing, Choice Neighborhoods and any unit built to Energy Star, Enterprise Green Communities, LEED or the performance path of the ICC-700 National Green Building Standard.

The agencies issued a Notice of Final Determination earlier this month establishing the standards as well as a timeline for when they are effective.

The notice included a nod to the National Association of Home Builders’s comments written last year when the preliminary determination was unveiled: NAHB asked for more time to allow builders and developers to make changes to their plans, and the final notice allows four months after the May 6 effective date for developers to file for FHA insurance under the existing program and grandfathers in seven months for single-family builders that already have obtained building permits.

It also acknowledges NAHB’s request to ensure cost effectiveness in any new requirements, estimating that the changes result in a payback of 5.2 years for low-rise residential, well within NAHB policy of 10 years.