There are many foundations (that I've inspected) that are falling apart and need immediate attention. Many homeowners have no idea where to start or what to look for. So I'm here to teach many of you how to properly maintain your foundation.
Your foundation is your home's infrastructure. It supports the floor, the wall, and roof framing. Moreover, the foundation helps to keep the floors level, the basement dry, and, believe it or not, windows and doors operate more smoothly with a good foundation. 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 (See "Wet Basements"). Once you have diverted all outside water away from your foundation, the majority of your foundation maintenance is complete.
POURED CONCRETE FOUNDATION
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. A simple parge coat of lime based mortar over any spalled or chipped areas will alleviate worsening of your foundation's condition.
If you notice any hairline cracks, simply monitor them for worsening. If you all of the sudden notice water stains at these cracks, be sure to correct all outside drainage first "See Wet Basements". After all exterior drainage is corrected and water still continues to seep into any cracks, you need to consider an epoxy injection that will definitely stop any future seepage at these cracks.
This type of stone foundation needs to be monitored on an annual basis. If your fieldstone foundation is not maintained over the years... bowing, bulging, shifting or settlement of your stone foundation may occur. If you find that any one these conditions have occurred, you should call in the services of an experienced Mason to make corrections to damaged areas immediately. However, if the stone surface is exposed, and they appear to be generally 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 many years to come.
Most fieldstone foundations have, or had at some time, a thin mortar coating on the face of the stone. The purpose of this coating was to assist in holding the stones in place. This thin mortar coating will inevitably flake off from any moisture migration, revealing the surface of the stones. As this coating continues to erode, the mortar between the stones will begin to crumble and the soft, sandy mortar begins to slowly fall out onto the basement floor. It looks like a small pile of sand at the base of the foundation. When this occurs, tuck pointing is needed to refill the voids where the old mortar has fallen out. It's very important that you scrape away or chip away the crumbling mortar (in between the stones) in order to establish a small cavity or key way which can hold the new mortar that is being applied. Never apply new mortar over any old crumbling mortar, as this is a temporary fix and it will only last a couple years. All crumbling mortar must be removed in order for the newly applied surface to bond properly. While upgrading your field-stone foundation, only work on a section at a time. Do not remove the old mortar throughout the entire basement all at once. Complete all removal, tuck pointing and parging one section at a time.
To avoid annual tuck pointing, you should finish the foundation with a complete top coating of mortar. Be sure it is lime based. This top coat does not have to look like a stone artisan's creation: It merely has to serve the purpose of keeping the newly installed mortar in place. It's sort of like applying a frosting to a cake. 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 in tact, your foundation will last forever.
If your fieldstone foundation seeps water, do not attempt to perform the above repairs until you correct your exterior drainage. Once your drainage is properly in place, and your foundation continues to seep water, you need to invest in a B-Dry system. I've seen many of these systems in place, resulting in very dry basements. I have never seen these systems fail so long as you continually maintain and test the sump pump and always have an additional sump pump on-hand in case the primary pump fails.
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 1/8" 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 tuck pointing the brick or block foundation, which means the removal by surface scraping (to establish a key way) and replacement of the 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), tuck-pointing is a project that is best left to a professional Mason.