Originally Posted By: dvalley
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Your foundation is your home’s infrastructure. It supports the floor, wall, and roof framing. Moreover, the foundation helps keep floors level, basements dry, and, believe it or not, windows and doors operating smoothly. Your foundation is also an anchor of sorts. Maintaining your foundation is necessary to avoid structural issues that can ruin your home very slowly.
The first and foremost requirement to maintaining your foundation is to correct any underlying moisture problems that your basement may be receiving from the exterior
(Read Part 5D ?Drying out a Wet Basement?). Once you have diverted outside water away from your foundation, the majority of your foundation maintenance is complete.
Poured Concrete
Poured concrete is tough stuff, but even concrete will crack, chip and crumble. Eventually, nature has her way. New England temperature extremes make their presence known through damage to concrete structures. I recommend that you inspect your concrete and masonry walls and slabs for damage on a regular basis. Early spring is an excellent time to assess any damage that may have happened from our winter freeze/thaw cycles.
Cracks, chips and broken or flaking areas in concrete are not only unsightly; they can lead to further deterioration of the surface and leaks if not properly maintained. The result is a costly replacement project as opposed to a simple repair once you notice damages.
Fieldstone
This type of stone foundation needs annual monitoring. A brief visual inspection of your fieldstone foundation may quickly disclose bulging, bowing, shifting or settlement of a stone foundation. If you find any one these conditions, you should call in the services of an experienced Mason to make corrections immediately. However, if the stones are exposed, and appear generally to be where the original builder placed them, you can probably handle the repairs and maintenance yourself. Determined do-it-yourselfers can perform much of the routine restoration and maintenance that will make their home's foundation last for future generations.
Most stone foundations have, or had at some time, a mortar coating on their interior. The purpose of this coating was to help hold the stones in place. This thin mortar coating will inevitably flake off from moisture migration, revealing the surface of the stones. As this coating continues to erode, the soft, sandy mortar in between the stones begins to fall out. When this occurs, re-pointing is needed as soon as possible to refill the voids where the old mortar fell out. It?s important that you scrape away the outside surface of any crumbling mortar in between the stones in order to establish a small cavity which can hold the new mortar that is being applied.
To avoid perpetual repointing, you will need to finish with a complete top coating. This top coat does not have to look like a stone artisan's creation: It merely has to serve the purpose of keeping the old mortar in place. Of all the components of a building that need either restoration or maintenance, the area buried deep in the ground is often the most neglected. By taking these steps to keep the mortar in between those stones upgraded, your foundation will last forever.
Slab Foundations
Slab foundations are the most modern, but they can vary considerably from older ones that have no moisture barrier beneath them and any reinforcing steel within them to newer ones that have moisture barriers beneath them and adjustable reinforcing steel within them. This type is called a post-tension slab, but is often impossible to distinguish one slab type from another in which even the size and spacing of the bolts can vary, although most are concealed.
My inspection of slabs conforms to industry standards. I examine the visible portion of the stem walls on the exterior of the structure for any evidence of significant cracks or structural deformation. However, I do not move furniture or lift carpeting and padding to look for cracks, and we do not use any specialized tools or measuring devices to establish relative elevations or determine any degree of differential settling. Significantly, many slabs are built to move out of level, but the average person would not realize this until there is a difference of more than one inch in twenty feet, which most authorities describe as being tolerable.
Interestingly, many slabs are found to contain cracks when the carpet and padding are removed, but there is no absolute standard for evaluating them. However, those that are less than ? ? and which exhibit no significant vertical or horizontal displacement are not regarded as being structurally threatening. They typically result from common shrinkage, but can also be caused by a deficient mixture of concrete, deterioration through time, adverse soil conditions and poor drainage, and if they are not sealed they can allow moisture to enter your home, and particularly if your home is surcharged by a hill or a slope, or if downspouts discharge adjacent to the slab. However, in the absence of any major defects, I may not recommend that you consult with a structural engineer or a foundation contractor, but this should deter you from seeking the opinion of any such expert. Also, the condition of utility lines (drainage, water, gas, electric, cable) that might run in, under, or through walls within slab-on-grade foundations cannot be determined due to construction.
Bricks and Blocks
Bricks, at one time, were used extensively to construct foundations. Today, however, if a foundation doesn't consist of concrete, it is probably constructed of concrete block. In either case, brick and block have one thing in common. They are both joined together using mortar, a combination of sand and cement.
Unfortunately, over time, the mortar tends to deteriorate. Cracked and deteriorating mortar joints are not only unsightly, they also diminish the integrity of the surface and can allow water to get behind the brick or block causing major damage. This can be avoided by tuckpointing the brick or block foundation, which means the removal by surface scraping and replacement of cracked, crumbling or missing mortar. Monitor your bricks and blocks periodically and upgrade when deterioration is obvious.
If the cracked or deteriorating mortar is extensive (an entire foundation wall), tuckpointing is a project that is best left to professionals.
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David Valley
MAB Member
Massachusetts Certified Home Inspections
http://www.masscertified.com
"Some cause happiness wherever they go; others, whenever they go."
