When to Perform a Geotechnical Investigation for Residential Construction

Photo: FHWA

One of the ways that the residential codes are more permissive than general building codes is their treatment of geotechnical investigations. Conventional residential construction is lightweight and the prescriptive foundation design provisions in the code are very conservative, yet typically cost-effective. There are circumstances, however, when performing a geotechnical investigation is beneficial or necessary for a residential project. Therefore, the decision as to whether to perform a geotechnical investigation warrants more attention then it usually receives.

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Why Your Pier Foundations May Not be “Code”

Depending on where you live, pier foundations are a common foundation type for residential structures. A pier foundation is a foundation type usually constructed of concrete or masonry that is relatively short compared to its width; a pier’s height will typically be less than 12 times its width or diameter (NYCBC 2014, 1801). Like a footing, piers derive support through end bearing on soil or rock. However, footings are wider than the elements they support and usually shorter in height than the walls or columns they support. Thus a footing transfers load to the ground in bending, while a pier transfers load in direct compression alone. Continue reading “Why Your Pier Foundations May Not be “Code””

Why There Are Cracks in Your Basement

Cracks in basement walls and floors are among the most commonly found types of structural distress in buildings, especially houses.  However, many homeowners do not know whether the cracks in their basement are problematic, if they are aware of them at all.

To understand why cracks form, you must first understand that structures and their components move.  They compress, extend and bend under applied load. There are also forces internal to elements of structures resulting from the behavior of the material or how the element was made.  Most structural materials expand with increased heat and moisture and contract in cold and dry conditions.  In addition, Portland cement-based materials, like concrete, concrete masonry and certain types of mortar, shrink as they cure.  Cracks occur when a structural element made of a brittle material is subjected to an external or internal force greater than its strength.

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