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They're easily overlooked, taken for granted and walked on all over! It’s your floors. Flooring in a home takes a beating year after year so it’s important to ensure that it’s functioning properly and has all the necessary supporting mechanisms in place such as sister-joists if you have sloping floors.  

Sloping Floors

Should You Worry About Sloping Floors?
If you're buying an old house with sloped floors, here's what you're getting:

  • Extra charm at no additional expense (the owner's perspective)
  • A structurally-unsound home (the inexperienced home inspector's perspective)
  • An ability to hose down your dining room floor (the practical homeowner's perspective)
  • In most cases, none of these choices is quite accurate.  Sloped floors are common in older homes, and even in homes as new as 15 to 30 years.

Sloping floors are most often caused by normal and acceptable deflection (bend) in the wood joists, which comprise the floor structure.  In some cases, the slope is caused or aggravated by similar deflection in the girder (main bearing beam) that supports one end of the joist sets.  But, even in this scenario, there is usually not a problem that needs repair.

As an organic material, wood joists are prone to deflection under load.  However, the amount of bend or deflection allowed by most building codes (typically, joist length divided by 360) does not address the nature of lumber to "creep."  Creep, in this sense, means to normally bend over a prolonged period of time.

A new floor design that satisfies code requirements for bearing capacity and rigidity (resistance to bend) may still be appreciably sloped after many years of service.  The likelihood a given floor has for bending is affected by many factors, but the most common primary cause is simply old age.  Pronounced floor slopes can, however, be an indication of a structural problem that needs attention.  If you are considering a purchase of any home with noticeably sloped floors, consider these four factors:

Age of the Home
Expect to find more slopes in an older home.  Even a slope as great as an eighth-inch per foot in an 80-year-old home may be no problem, while any readily discernible slope in a 5-year-old house would be reason for concern.

Direction and Shape of the Slope
Floors that dip in the middle are usually caused by non-structurally significant joist deflection, but sloped or tilted floors that are straight (i.e. slope in one direction) may indicate a more serious foundation or bearing wall problem.

Joist Sizes, Spans and Spacing
Assessing the design of a floor system usually requires a professional engineer, but as a gross general guide, joists that are 2 inches by 8 inches, and are set 16 inches apart (standard), are suitable for spans of up to about 12 feet.  Joists that are 2 inches by 10 inches at the same spacing are suitable for spans of up to about 16 feet.

If you have sloped floors with 2-inch by 10-inch joists that run 18 feet between the end supports, you probably have, or will have, a problem.

The species and grading of the lumber also impacts its span ability.  The Western Wood Products Association has an easy-to-use online span table.

Wall Crack Patterns
Some wall cracks can indicate evidence of an ongoing problem.  Look carefully at the interior door frames set in partition walls parallel to the joist runs.  Look for diagonal crack patterns extending from the top corners of the doorway.  Hairline cracks, or cracks that have been sealed, indicate stability (assuming the house has not recently been painted).  Larger, newer cracks indicate a possible problem.  If the house has a bathroom next to the sloped floor room(s), look at the wall tiles.

Ceramic tiles are non-resilient and will crack readily, so they are often good indicators of movement.  For example, in a 100-year-old house we may not pay much attention to moderate floor slopes, but if the same house has a new bathroom with large cracks in the wall tiles, we know that the movement has recurred or worsened since the new bathroom installation.  This may be a problem.

Most importantly, if in doubt, consult an experienced home inspector or engineer.  While most sloped floors are simply "charming," such slopes may also indicate a serious problem.

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Kitchen Floors

The flooring material can be ceramic or vinyl tile, wood, or vinyl sheet goods. Check for nicks, tears, warping, missing grout, and openings at the seams. Carpet is not a recommended kitchen floor surface, particularly if there are children in the family. Carpeting tends to hold moisture and bacteria from food spills. Wood floors have become very popular in kitchens, however, they are more difficult to maintain and can be slippery when wet. Floor maintenance for wood is regular cleaning and periodic refinishing.

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Carpet should be checked for proper stretching and securing of the seams, mostly for safety.  Loose carpet may pose a tripping hazard. Carpet should be checked for dirt and stains that might be permanent, which will require replacement. Carpeting can also affect the air circulation of the HVAC system.  If the carpet is too thick, and the HVAC system doesn’t have individual returns, it could block the air space underneath some of the interior doors, restricting adequate air circulation to those areas. In such cases, the door could be undercut. Beware of carpeting in bathrooms as there is almost always a moisture retention and damage concern.

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Ceramic Tile can be set in a wet bed system or thin set (mastic). A wet bed system, referred to as “mud” in the trade, is a cement, sand, and lime mix similar to that used for the ground coat of a three-coat plaster wall. Thin set/mastic is an adhesive that has enough body to help smooth and fill minor imperfections that may exist in the sub flooring, and secure the tiles to the floor or wall. The wet bed system is more desirable and longer lasting, but it is more expensive. New products, such as the mastics and waterproof boards, are making wet bed systems extinct.

Loose tile, due to failing and water-damaged substrates, is a major problem.  Tap floor tile in suspicious areas and gently tap or press wall tiles to locate loose and possibly damaged areas. 

Grouting around the tub and shower should be maintained, as failure to do so leads to the deterioration of the tile and allows water to seep into the areas and substrates below. Grout between the tiles is more stable than grout at dissimilar materials, such as where the tile meets the tub or wall. These areas need a flexible material, such as silicone or similar caulk. Wood floors will generally be more flexible than ceramic tile. Grout with plasticizers should be used over wood floors. This will allow the grout to flex between the tiles instead of causing the tiles to crack.

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Hardwood floors are very common in today’s market. The most commonly used wood is oak.  It is usually identified by its hardness and is normally installed in two types—3/4-inch by 2 1/4-inch tongue & groove (T&G) boards, or 5/16 by 2-inch, square edge boards that are surface nailed. The material can be easily filled, sanded, stained and finished.

Parquet floors are usually high quality floors. Generally, they are 12 x 12 x 1/2 inches thick. They can be square edge or T&G, and are generally installed with an adhesive. The most common problem with this flooring is that the adhesive loosens over time. You can usually detect this defect when you walk over the loose area. Floors tend to loosen with moisture or conditions with high relative humidity, and in high traffic areas. Parquet floors are generally constructed of:

  • 3/4-inch T&G
  • 3/8-inch T&G
  • 1/2 inch that includes plywood laminated to a thin piece of hardwood (like a veneer)

These floors look great and are durable. However, they have a “V” joint between the pieces, which makes re-finishing difficult. This joint tends to attract dirt, debris, and grease over the years, which makes cleaning and preparing the floor tedious.

Stains are very difficult to remove from any type of wood flooring, whether it is site finished or refinished at the factory. Sanding can remove some of the stains, but deep, oil-penetrating stains are almost impossible to totally remove.  Pet stains (e.g. urine) may sand off if minor and superficial, but if serious stains, replacement of the affected areas may be necessary.

Pine Floors
Most pine wood flooring is yellow pine and generally found in older construction. In homes built roughly 70 to 100 years ago, it will typically be found on the third and second floors over a sub-floor, as well as in attic areas. Homes built 100+ years ago are more likely to have square edge pine board flooring. In many cases, there will be no sub-floor. When present, attic flooring is usually a flat grain, usually only found in the attic spaces of older homes.

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Vinyl tile products are dependable, as long as the installation is performed properly. There is a wide range in quality. Loose tiles are often a sign of moisture or workmanship concerns, particularly in the kitchen and basement areas.

Vinyl-asbestos tile is also dependable and durable, and was the tile of choice for decades until it was discontinued for residential applications in 1973.  Manufacturers had until 1978 to deplete their stock and cease distribution. The concern is related to the asbestos components within the tile. Asbestos has been used for over a century as a binder in tile. This asbestos application is not considered a health hazard because it is not friable or airborne.

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Common Defects

Not all floors have an equal lifespan, especially given the variety of traffic, exposure and whether or not the floors themselves are maintained properly. Be sure to take close account of your floors from time to time using the following defects as a guide.

  • Not level
  • Ridges or sags
  • Squeaks
  • Vibrations
  • Loose nails
  • Rot or insect damage
  • Inadequate live load strength
  • Detached from joist or sub-floor
  • Stained
  • Broken tile
  • Loose grout
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