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A masonry foundation is a structural foundation made from masonry. Historically, bricks or dressed stone were often used to create this type of foundation. Today, concrete masonry units (CMUs) are a common choice of building material for a new masonry foundation or a retrofitted foundation. The purpose of a masonry foundation is to support the weight of a structure while distributing the weight across subsurface strata, and to act as an anchor to keep the structure in place.
Masonry foundations are established in the form of perimeter or pier foundations. A perimeter foundation follows the footprint of the structure, with the weight being transferred evenly across the entire perimeter. Pier foundations consist of a series of masonry piers scattered across the footprint to support the weight, which is typically transferred by posts. Perimeter foundations are generally preferred in new construction.
A number of considerations go into the design and installation of a masonry foundation. It is important to make sure that the foundation is large and study enough to support the weight of the structure, and to address issues such as groundwater seepage. A masonry foundation is at risk of a number of problems which can be addressed during the design phase to make the foundation more stable. A poorly designed foundation can fail, causing serious problems and leading to expensive repair bills.
One common issue is settling and ground movement. Over time, ground naturally settles, which causes houses to list. In extreme cases, houses can even crack in two as a result of settling. Ground movement caused by earthquakes, landslides, and other events can also be a problem, as can frost heave, which occurs in cold climates. Water intrusion is also an issue, especially when a house is built into a hillside, in which case water runoff will tend to erode the foundation.
The depth of a foundation varies, depending on the size of the structure. High rises need very specialized foundations which penetrate deep into the ground to anchor and support the structure. Homes need much smaller foundations, and have less stringent design requirements. It is also much easier to retrofit the foundation of a home, with the home simply being jacked up while the foundation is replaced. While the foundation is being retrofitted, it is usually possible for people to continue using the structure, although they may need to exercise caution to avoid disturbing the jacks used to hold the house up.
@bythewell - The problem with the buildings in Christchurch wasn't that they had masonry foundations necessarily. The problem was that there were a lot of historic buildings which were made without earthquakes in mind at all.
They would have had traditional masonry foundations, and I don't think those have much give to them.
The region was not known to be earthquake prone, so even residential foundations which generally don't need all that much to be made safe, weren't required to be built to that kind of code.
I think that, when rebuilding, people will take earthquakes very seriously and will integrate every measure possible into their foundations, masonry or otherwise.
I had a friend who worked for an architectural design company and they were involved in designing many of the buildings that were in Christchurch before the big quakes in early 2011.
After the first quake I know they were really pleased with how the buildings had held up. I think a lot of them had masonry foundations and there is no way of really earthquake proofing that kind of foundation entirely.
On the other hand, there aren't all that many alternatives to a masonry foundation when it comes to larger buildings.
Of course, because of the second quake, they will have to rethink everything. Now even the least affected building seem to have cracks in their foundations.
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