The builder's representative, who is supposed to look after any complaints, indicated that this should not pose any problem for the replacement floor. After all, he argued, the floor installer is not an engineer. There was obvious resistance to even acknowledging that there was anything structurally wrong. We are very concerned about the seriousness of a beam that is bowed, and joists that are not level. He advised us to work at straightening the floor with telepost adjustment. This does not address the concern about the joists, however.
What is the tolerance level for the sub-floor hills and valleys? In my check of a four foot stretch, there were discrepancies of up to 5/16th of an inch in various areas of the floor. I am in the process of lowering the high points of the beam by adjusting the teleposts, one quarter of a turn every few days, but it has not seemed to improve the floor level. We would appreciate some advice.
-- John Shirley Bestvater, e-mail
Answer -- Uneven or defective floor coverings in new homes is a common complaint, one that seems to be increasing due to the expanding selection of materials available. Hardwood has always been a potentially problematic material for this purpose, due to the normal properties of the natural wood. Hardwood will shrink or swell, somewhat, if the amount of moisture in the wood is increased or decreased quickly due to environmental factors. This may or may not be the true cause of the problem in your home, which may be due to different factors.
Ideally, hardwood flooring should be acclimatized in the area inside the building under construction, for a period of several weeks, prior to installation. The reason for this is due to differing environmental factors between the location that the material has been stored and the new home. Particularly of concern is the relative humidity, which can be extremely high in a new building and may be dramatically different from the dry warehouse that it came from. Strip hardwood flooring is normally kiln dried to a specific moisture content, which may even drop slightly during storage. If this dry material is installed in the humid environment of a new home without acclimatizing, it may swell and buckle shortly after installation. Conversely, if the moisture content of the hardwood is too high, it may shrink after installation, leaving gaps between the individual boards.
According to the performance guidelines of Tarion, which is the former Ontario Home Warranty Program, "strip hardwood flooring or parquet flooring shall be installed to provide a surface where adjacent strips have no more than a two mm difference in elevation". They also go further to state that, "applied finished flooring shall be installed without visible ridges or depressions. Where visible ridges or depressions occur, the variation from the specified plane shall not exceed plus or minus six mm. This is less tolerance than you have observed over a short span, which would suggest that there is indeed a problem that needs remediation. While these performance standards are important, I don't believe that what you are experiencing is a problem with the flooring itself. As the second flooring installer has suggested the subfloor or the floor structure is the likely culprit for your uneven floor.
Variation from one floor joist to the next can be quite common if your floor structure is natural wood, especially with the mixture of spruce/pine/fir framing material commonly used today. Unlike the hardwood flooring, this material may have quite high moisture content depending on how freshly it has been milled. It may be only partially air dried and may also absorb considerable more moisture if it is left in the open elements during construction. Melted snow or rain can easily be soaked up by the fresh lumber and may also be unevenly distributed between different layers in the same pile. The outside boards may be soaking wet, after a heavy rain, while the inside pieces remain relatively dry, and vice versa. After installation, this wood will dry out and can shrink considerably across the grain, which will reduce the width of the dimensional lumber. Also, wet wood may warp or twist as it dries, which may cause further variations from one joist to the next. This uneven shrinkage can cause boards to "crown" or bow upwards or downwards. If adjoining floor joists shrink to different degrees or have opposing crowns, one laid upwards and the next one downwards, that can cause the unevenness you are seeing in your home.
While some telepost adjustment may be required after construction, even on a home with poured concrete pier or pile foundations, these should initially be minimal and may not yield a solution to your uneven floor. Consultation with a professional structural engineer to evaluate the floor structure should be your next step before proceeding with any more telepost adjustment or flooring replacement to prevent improper or unnecessary repairs.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the President of the Canadian Association of Home Property Inspectors - Manitoba (www.cahpi.mb.ca). Questions can be e-mailed or sent to: Ask The Inspector, P. O. Box 69021, #110-2025 Corydon Ave., Winnipeg, MB. R3P 2G9. Ari can be reached at (204) 291-5358 or check out his new website at www.trainedeye.ca
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