Photograph of a collapsing concrete block foundation wall. Repair Methods for Bulged or Cracked Foundation Walls

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Bulged foundation wall repair methods:

This article explains how to Repair Bulged, Cracked Building Foundations using pilasters, steel reinforcement, foundation anchors, sister walls, or wall reconstruction methods. In this masonry foundation or wall repair article series we explain how it is possible to be confident about the cause of and repair for foundation damage, and we describe various methods used to repair cracked or bulged, bowed or in some cases leaning or tipped foundation walls.

The photograph at the top of this page shows a concrete block wall which has bulged and is in danger of collapse due to earth pressure from outside. The photo above shows a foundation wall reconstruction in process for a poured concrete foundation wall that settled and cracked at the time of construction.

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A Guide to Repair Methods for Bulged Foundation Walls

Sketch of a method for repairing a bulged concrete block wall © Daniel Friedman at

Here we illustrate and describe several methods used to stiffen or reinforce bulging foundation walls against further movement.

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Article Contents

The motive for a decision to reinforce a building foundation rather than rebuild it can be easily understood by noticing the difference in cost between bolting a few vertical steel beams to a building or building a pilaster and the cost to add temporary support to the floors above, remove an existing foundation, and rebuild a new one in its place.

[Click to enlarge any image]

However the decision to support or reinforce a foundation wall versus rebuilding it is often made by the wall itself. If the amount of bulge or bow is sufficiently severe the wall needs to be rebuilt.

If the underlying source of wall damage cannot be reliably addressed without excavating outside to add drainage and perhaps water proofing, there is additional motivation to perform a more costly repair.

The foundation bulge or lean repair methods listed below are roughly in order of their most common appearance in residential buildings. The sketch shown here describes application of a steel I-beam against a masonry block wall for reinforcement. More details are given below.

Guide to Using Pilasters for Repair of Foundation Wall Bulge, Cracks, Movement

Photograph of Pilasters constructed against the existing foundation wall.

Pilasters may be constructed against the existing foundation wall(s) to add stability and resist further movement.

The Carson Dunlop Associates sketch below shows how a pilaster may appear in a building for a different reason than an attempt to stiffen a bulging foundation wall. In this case the pilaster is supporting a beam placed as a girder to support the floor that will be constructed above. So don't assume just because you see a pilaster that it was built to address a foundation damage problem.

Spread footings and pilasters schematic (C) Carson Dunlop Associates

A pilaster is a masonry column or short wall which is constructed butting against the original wall at right angles. In this photo the masonry block pilaster is itself damaged and spalling. Additional repairs and steps to direct water away from this foundation wall are still needed.

Guide to Using Reinforcing Steel I-Beams for Repair of Foundation Wall Bulge, Cracks, Movement

Photograph of Steel I-beams or U-channel beams placed against the bulged wall

Steel I-beams or U-channel beams may be placed against the bulged wall, anchored at their bottom to the floor slab and at their top to building floor framing.

The beam is placed with its side against the most-inward-protruding portion of the wall. The I-beam or U-channel may not be in full contact with the bulging foundation wall but it would be expected to be in contact with the inwards-most portion of the wall to stop further movement.

When you click on the photos below you'll see how the installer used a simple wood cross-bridge between the joists of the floor above to hold the top of the "I" beam in place against the foundation wall.

Often the bottom of the vertical I-beam used to reinforce a bulging foundation wall (shown below) is secured by breaking a hole into the concrete floor slab where the bottom of the I-beam is cemented in place.

Wavy mortar backfill damage to a block masonry wall © Daniel Friedman at

Because the total bulge in the concrete block wall above was minor, and because analysis of the wall gave convincing evidence that the only wall damage and movement had occured at time of construction, during backfill, the contractor repaired the wall by adding safety-reinforcement: steel I-beam pilasters secured to the floor structure at the wall top and let into the concrete slab at the wall bottom.

The I-beam contacts the concrete block wall only at its most inward-bulged point.

At the top of the I-beam used to try to stop the bulging foundation wall, the I-beam is fastened to the building floor framing system as shown below.

Wavy mortar backfill damage to a block masonry wall © Daniel Friedman at

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Example of Using Foundation Anchors for Repair of Foundation Wall Bulge, Cracks, Movement

Photograph of Foundation Anchors

Foundation Anchors may be used to stabilize a foundation wall which is not badly damaged. This approach uses horizontal driven pins to anchor the wall to the surrounding soil and resist resist further movement.

Special products are available which employ an expanding soil anchor at the outside end of the horizontal pin.

In this photograph we show a rectangular steel plate and just the end of a threaded steel rod which is all that one can see of the foundation anchor which had been driven through the foundation wall and into the surrounding soil.

Guide to Using Interior or Exterior Reinforcing Sister Walls for Repair of Foundation Wall Bulge, Cracks, Movement

Photograph of Foundation Anchors

An inside or outside foundation-reinforcing wall may be constructed against the bulged foundation wall. Unless the outside cause of bulging (such as water or frost) is also corrected, we are doubtful about the durability of this approach. In this photograph there had been a history of water entry and foundation wall cracks and movement at the front of this office building built with a portion of its foundation wall sitting on sloped bedrock.

Photograph of Foundation Anchors

The contractor built a reinforced concrete block against the damaged foundation wall, an effort which was largely successful at reducing most, but not all of the water entry (and mold) in the building. Simple measures outside to properly handle roof runoff by directing it against the foundation, and normal gutter maintenance, would help considerably in drying out this area.

The sketch describes application of a reinforced concrete wall on the exterior of a building foundation.

Using Cables for Repair of Foundation Wall Bulge, Cracks, Movement

Steel tension cables + stars (reinforcing plates) are sometimes used to anchor the wall to the surrounding soil and resist further movement but more normally this approach is used to strengthen and cross-tie above-ground walls in masonry buildings. It's common to see these outside reinforcing plates on pre-1900 multi-story brick buildings which no longer rely just on floor framing to tie opposing masonry walls together.

Reconstruction as a Repair of Foundation Wall Bulge, Cracks, Movement

Photograph of a reconstructed concrete block foundation

Reconstruction of the entire foundation wall is the repair usually called-for by masons and while probably the most-costly, is often the most effective repair method since it permits installation of drainage around the wall exterior as part of the procedure:

excavation and reconstruction of a near-failing or failed foundation wall may possibly include in the new wall, additional reinforcement over the original design and with additional foundation and site drainage.

In the photo shown here the rear and a portion of the rear right masonry block foundation walls had to be rebuilt after the foundation began to collapse during a period of heavy rain.


Continue reading at FOUNDATION BULGE or LEAN MEASUREMENTS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see FOUNDATION CRACK DICTIONARY for a discussion of the diagnosis of specific crack patterns in masonry

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