Blog Archives

Jacking refers to raising or lowering a building so you can repair or replace defective framing or failed foundations or to level a house that has set­tled excessively. Shoring refers to a temporary system of posts, beams, and other structural ele­ments that support building loads. Temporary is the crucial word: Shoring supports the building between jackings. Once repairs are complete, you need to lower the house and remove the shoring as soon as possible. If repairs are extensive—say, replacing foundation sections—have a structural engineer design the new sections; specify jack size; and specify the posts, beams, and bracing needed to safely jack and shore the building.

Jacking a house is nerve-wracking...

Most foundations that fail were poorly designed, poorly constructed, or subjected to changes— especially hydrostatic pressure or soil movement —that exceeded their load-bearing capacities. Exact causes are often elusive.

for a span or by a failed or absent girder. If an existing girder seems sound, adding posts or new pads may fix the problem. Otherwise, add a girder to reduce the distance joists span.

Flooring that crowns above a girder, sloping downward toward the outside walls; doors and windows that are difficult to open; and cracking at the corners of openings are often caused by a failure of all or part of the perimeter foundation.

Foundation cracks often signal foundation fail­ure...

In many parts of North America, building codes don’t require steel reinforcement in concrete foundations, but steel is a cost-effective means of avoiding cracks caused by lateral pressure on foundation walls.

Steel reinforcement and fasteners. Steel re­inforcing bar (rebar) basically carries and distrib­utes loads within the foundation, transferring the loads from high-pressure areas to lower-pressure areas. It thereby lessens the likelihood of point failure, either from point loading above or from lateral soil and water pressures. Anchor bolts or threaded rods, tied to rebar, attach the overlying structure to the foundation. Steel dowels are usu­ally short pieces of rebar that pin foundation walls to footings, new sections to existing foun­dations, and so on.

There are also a number o...

Foundation issues

before starting extensive remedial work, such as replacing failed foundation sections or adding a second story to your house, have a structural engi­neer evaluate your foundation. In addition, bring in a soils engineer if the site slopes steeply or if the foundation shows any of the following dis­tress signs: bowing, widespread cracking, uneven settlement, or chronic wetness. Engineers can also assess potential concerns such as slide zones, soil load-bearing capacity, and seasonal shifting.

An Overview

A foundation is a mediator between the loads of the house and the soil on which the foundation rests. A well-designed foundation keeps a house’s