How to inspect a wood foundation:

Preserved wood building foundations: this article explains wood building foundations, their inspection, installation, diagnosis, repair, and durability. Page top sketch of a basic wood foundation design is provided courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

How to Identify, Diagnose, & Evaluate Wood Foundation Defects

Some building jurisdictions permit the use of preserved or "treated" wood products for below-grade building foundations. These materials offer advantages of construction speed and low cost. As in the installation of Concrete Pre-cast Foundation walls, treated wood foundations may be installed on a gravel pad rather than requiring a solid masonry footing.

Suggestions for Inspecting a preserved wood foundation

• Check for evidence of foundation leakage at butt-joints where gaskets or sealant may have been omitted.
• Check for evidence of buckling or other damage;
• Outside check for the presence of a moisture barrier against the foundation exterior.

Our opinion is that "30-year guaranteed treated wood foundation products" used below grade mean that no permanent building foundation has been provided. This sketch of the components of a preserved wood foundation is courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

Buildings using a wood foundation are in our OPINION a temporary structure. In areas of wet soils and insect damage risk damage may occur sooner than the warranty period.

CONTACT us by email to suggest photos or content regarding wood building foundations.

Note: use of plumb lines, levels, laser levels, & simple measurements of amount by which a wall is out of level or plumb, or of crack widths and patterns are beyond ASHI or other home inspection standards scope but are common simple tools and procedures used by masons, carpenters, builders, as well as foundation experts and engineers.

Below are some articles that offer additional foundation damage analysis methods that pertain to wood foundations as well as other foundation types:

• FOUNDATION BULGE or LEAN MEASUREMENTS explains a simple method for determining how much bulge or lean is present in a foundation or wall,
• FOUNDATION MOVEMENT ACTIVE vs. STATIC helps determine if the foundation movement is ongoing,
• FOUNDATION DAMAGE SEVERITY discusses how we decide the severity of foundation damage and the urgency of further action.
• FOUNDATION FAILURES by TYPE & MATERIAL describes the types of foundation damage, cracks, leaks, or other defects associated with each type of foundation material (concrete, brick, stone, concrete block, etc.).

Watch out: a novice inspector may have trouble distinguishing between a completely-wood foundation and a pre-cast concrete foundation wall such as the structure shown above. If the sills and studs in this wall are concrete then it's almost certainly a pre-cast concrete foundation even though you may see plywood or OSB on the inside surface of the foundation cavity wall.

Sources Of & Research On Pre-Fab Wood Foundations & Prefab Construction

• Brege S, Johansson HE, Pihlqvist B. Wood Manufacture: The Innovation System that Beats the System. VINNOVA; 2005.
• Brock L, Brown J. The Prefabricated House in the Twenty-First Century: What Can We Learn from Japan? A Case Study of the KST-Hokkaido House. InWorld Conference on Timber Engineering 2000.
• Dickens HB. Trends in Canadian house production. [PDF] NRC Publications Archive, National Research Council Canada, (1968), NRC Publications Record / Notice d'Archives des publications de CNRC, source: Contact us / Contactez nous: nparc.cisti@nrc-cnrc.gc.ca. - retrieved 2015/12/09
• Dunkley D. Prefab shear walls. Journal of Light Construction. Dec. 1999 Dec.
• Filiatrault A, Stieda CK. Seismic weaknesses of some residential wood framed buildings: confirmations from the 1994 Northridge earthquake. Canadian Journal of Civil Engineering. 1995 Apr 1;22(2):403-14.
• Goverse T, Hekkert MP, Groenewegen P, Worrell E, Smits RE. Wood innovation in the residential construction sector; opportunities and constraints. Resources, Conservation and Recycling. 2001 Dec 31;34(1):53-74.
  Abstract
  We study the opportunities to increase the use of wood in the Dutch residential construction sector and assess the effects on material related CO2 emission. Four house types are modeled with increasing quantities of wood used in constructions. CO2 emission reductions of almost 50% are technically possible. We assess the innovation characteristics of these wood applications to create insights in the complexity of the necessary change process. Then we relate the innovation characteristics of the wood options to the context in which implementation of the technologies take place. The options vary strongly in the required technical and network changes and so do the opportunities to implement them. Based on this we expect that a 12% CO2 emission reduction related to material use for residential buildings is possible in the short term by an increased share of wood use. We also study the possibilities for increased wood recycling practices. A large technical potential exists. To achieve this potential a significant policy effort is needed since significant changes in both technical and network dimensions are necessary. To stimulate innovation in the use of wood in residential construction, important focus points of policy making should be the culture in the Dutch construction sector, the way new building projects are commissioned, research areas within the building sector, and stabilization of building networks.
• Lehmann S. Low carbon construction systems using prefabricated engineered solid wood panels for urban infill to significantly reduce greenhouse gas emissions. Sustainable Cities and Society. 2013 Feb 28;6:57-67.
  Abstract
  Low-carbon prefabricated modular construction systems, using prefabricated engineered solid wood panel construction systems, such as load-bearing cross-laminated timber panels, and ‘design for disassembly’ principles will offer significant opportunities for greenhouse gas emission reduction and waste avoidance, among other benefits. However, introducing such innovative and sustainable construction systems to the Australian construction industries and housing markets has its challenges.
  This paper explores the opportunities offered by an innovative low carbon construction system using cross-laminated timber (CLT, also known as cross-lam) panels to improve the design and delivery of urban infill housing of the Australian construction market. CLT construction has been developed around 1996 in Europe, mainly in Austria and Germany: thick layers of timber boards are glued crosswise in different directions to increase loadbearing capacity. This article describes a multi-disciplinary research project into engineered timber panels which aims to transform the Australian construction and development industry, involving a range of key partners. This project aims to introduce CLT panels as a way to build with a lightweight prefabricated low-carbon construction system that is advantageous for urban infill and residential buildings in the range of 4–10 stories height. The challenges, research questions and advantages of this new engineered timber system are explained, and a research methodology for further research is presented.
• Loferski J, Kochkin V, Platt RT. Development of ready-to-assemble wood structures. InProceedings of the 6th World Conference on Timber Engineering. Whistler, BC, Canada 2000.
• Luo, Yupeng, David R. Riley, and Michael J. Horman. "Lean principles for pre-fabrication in green design-build (GDB) projects." (2005): 539.
• Mahapatra K, Gustavsson L. Cost-effectiveness of using wood frames in the production of multi-storey buildings in Sweden.
• Moody R, Ritter M. Structural wood products. InProceedings of the First Materials Engineering Congress Pt 1990 (Vol. 1, pp. 41-52).
• Noguchi M. The effect of the quality-oriented production approach on the delivery of prefabricated homes in Japan. Journal of Housing and the Built Environment. 2003 Dec 1;18(4):353-64.
• Orr RA. Canadian Practice in Wood Frame Construction. National Research Council Canada, Division of Building Research; 1966 Apr.
• Rasmussen TV. Prefabricated Elements Used as Strip Foundation of Single-Family Housing. In Buildings X Conference, Thermal Performance of the Exterior Envelopes of Whole Buildings X 2007.
• Rasmussen TV. Prefabricated EPS Elements used as Strip Foundation of a SinglefamilyHouse with a Double Brick Wall. Nordic Journal of Building Physics: Acta Physica Aedificiorum. 2008.
  Abstract:
  A new prefabricated lightweight element was designed for a strip foundation that was demonstrated on site as the base of a single-family house with a double brick wall. The element was placed on a stable surface underneath the top soil layer, just 0.25 m underneath the finished ground surface. The prefabricated element was designed to fulfil the requirements of low energy consumption required by the new Danish Building Regulations. The base of the house was cast in one working operation and completed within two working days. The element, made of expanded polystyrene, was designed to be handled on site by one man. A non-freezing ground was established by using outer insulation located at the outer plinth. Temperatures were measured at measurement points located at the outer plinth and onwards from these points underneath the building. In addition the soil temperature, the temperature within the concrete floor slab and indoor and outdoor temperatures and relative humidity were measured.
• Shyamasundar SK, Vengala J. Promotion of bamboo housing system and recent development.
• Spelter H. Comparing in-place costs of wood and masonry foundations. Forest Products Journal. 1983 Jan 1;33(9):45. [PDF] retrieved 2015/12/09, original source: http://www.fpl.fs.fed.us/documnts/pdf1983/spelt83a.pdf
  Abstract:
  This study analyzes the in-place costs of treated-wood foundations versus masonry foundations. The use of wood foundations in homes and low-rise structures is not high although the growth rate is strong. The potential for increasing lumber and plywood use in homes is significant if the wood-foundation system continues to perform well and the economics remain favorable. Labor and material cost data for the years 1974, 1977, 1980, and 1981 were collected and combined with the labor and material requirements of wood and masonry foundations in 1969. Based on the data, the in-place costs of both foundations were calculated for those periods. For each of the 4 years examined, treatedwood foundation costs were lower than masonry costs, as much as 10 percent lower in the recession-affected year of 1981. Lower labor costs strongly favor wood foundations as do very low lumber and plywood prices experienced in the early eighties.
• Toole TM. Technological trajectories of construction innovation. Journal of Architectural Engineering. 2001 Dec;7(4):107-14.
• Trent RL, Whiteside TM, Robertus J. Field Experiment on a Prefabricated Expandable Foam/Wood Structure. CONSTRUCTION ENGINEERING RESEARCH LAB (ARMY) CHAMPAIGN IL; 1976 Oct.
• Vorgefertigter Wl, Beanspruchung Z, Prefabriques P, Lamelle Me. Racking Behaviour Of Light Prefabricated Cross-laminated Massive Timber Wall Diaphragms Subjected To Horizontal Actions. Otto-graf-journal. 2006;17:125.
• Wraber I. Comparative study of Danish prefab houses made of wood. In6th Nordic Conference on Construction Economics and Organisation 2011 Sep 3 (pp. 441-452).
• Zal FH, Cox K. Pre. Fab: Myth, Hype+ Reality. InWood Structures Symposium 2009 Jul 7 (p. 15).

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Continue reading at STRUCTURAL DAMAGE PROBING or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• FOUNDATION FAILURES by TYPE & MATERIAL
• FRAMING DAMAGE, INSPECTION, REPAIR - home
• INSECT INFESTATION / DAMAGE - home
• WOOD STRUCTURE ASSESSMENT

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