Standards / Wood Floor Framing Floor System

Wood Floor Framing Floor System


 

Coverage 1st Year Only

Workmanship and Materials

Floor Systems

3-1-1

Observation: Springiness, bounce, shaking, or visible sag is present in the floor system.

Performance Guideline: All beams, joists, headers, and other structural members shall be sized and fasteners spaced, according to the National Forest Products Association span tables or local building codes.

Corrective Measure: The Bolster Contractor will reinforce or modify, as necessary, any floor, wall, ceiling, or roof not meeting the performance guideline.

Discussion: Deflection may indicate insufficient stiffness in the lumber, or may reflect an aesthetic consideration independent of the strength and safety requirements of the lumber. Joists and rafters are required to meet standards for both stiffness and strength. The span tables allow, under full design loadings, a maximum deflection equal to 1/360 of the span for floor and ceiling joists (3/8 inch in 12 feet), 1/240 for rafters up to 3/12 in pitch (1/2 inch in 12 feet), and 1/180 for rafters over 3/12 in pitch (3/4 inch in 12 feet). Structural members are required to meet standards for both stiffness and strength. When an owner's preference is made known before construction, The Bolster Contractor and the owner may agree upon a higher standard.

 

Beams, Columns, and Posts

3-2-1

Observation: An exposed wood column or post is split.

Performance Guideline: Sawn wood columns or posts shall meet the grading standard for the species used. Splits that exceed 3/8-inch in width and more than 4 inches in length at time of installation or that develop during the warranty period are considered unacceptable.

Corrective Measure: The Bolster Contractor will repair or replace any beam or post that does not meet the guideline. Filling splits is acceptable to have structural members meet the guideline.

Discussion: Some characteristics of drying wood are beyond the control of The Bolster Contractor and cannot be prevented. Compensation is made in span tables for the probable reduction in strength resulting from splitting caused by drying.

Therefore, splitting is primarily an aesthetic concern rather than a structural problem. Checks and splits, which occur during the drying of lumber have the effect of reducing the area in the plane of shear resistance. Consequently, laboratory data developed for shear parallel to grain are reduced substantially for design purposes in order to accommodate the probability of the occurrence of checks and splits after drying.

 

3-2-2

Observation: An exposed wood beam is split.

Performance Guideline: Sawn wood beams shall meet the grading standard for the species used. Splits that exceed 3/8-inch in width and 4 inches in length at time of installation or that develop during the warranty period are considered unacceptable.

Corrective Measure: The Bolster Contractor will repair or replace any sawn wood beam that does not meet the guideline. Filling splits is acceptable to have structural members meet the guideline.

Discussion: Some characteristics of drying wood are beyond the control of The Bolster Contractor and cannot be prevented. Compensation is made in span tables for the probable reduction in strength resulting from splitting caused by drying.  Therefore, splitting is primarily an aesthetic concern rather than a structural problem. Checks and splits, which occur during the drying of lumber, have the effect of reducing the area in the plane of shear resistance. Consequently, laboratory data developed for shear parallel to grain are reduced substantially for design purposes in order to accommodate the probability of the occurrence of checks and splits after drying.

 

3-2-3

Observation: An exposed wood beam or post is twisted or bowed.

Performance Guideline: Exposed wood posts and beams shall meet the grading standard for the species used. Posts and beams with bows and twists exceeding 3/4-inch in an 8- foot section shall not be installed, and those that develop bows and twists exceeding 3/4- inch in an 8-foot section are considered unacceptable.

Corrective Measure: The Bolster Contractor will repair, sister, or replace any beam or post with a defect that exceeds the guideline.

Discussion: Beams and posts, especially those 3 1/2 inches or greater in thickness (which normally are not kiln dried) will sometimes twist or bow as they dry after milling or installation. Twisting or bowing is usually not a structural concern if posts and beams have been sized according to manufacturers' specifications or local building codes.

 

3-2-4

Observation: An exposed wood beam or post is cupped.

Performance Guideline: Cups exceeding 1/4-inch in 5-1/2 inches are considered unacceptable.

Corrective Measure: The Bolster Contractor will repair, sister, or replace any beam or post with a defect that does not meet the guideline.

Discussion: Cupped lumber is lumber that has warped or cupped across the grain in a concave or convex shape. Beams and posts, especially those 3-1/2 inches or greater in thickness (which normally are not kiln dried), will sometimes cup as they dry after milling or installation.

 

Subfloor and Joists 

3-3-1

Observation: Floor squeaks or the sub floor appears loose.

Performance Guideline: Squeaks caused by a loose sub floor are unacceptable, but totally squeak-proof floors cannot be guaranteed.

Corrective Measure: The Bolster Contractor will refasten any loose sub floor or take other corrective action to eliminate squeaking to the extent possible within reasonable repair capability without removing floor and ceiling finishes.

Discussion: Floor squeaks may occur when a sub floor that has come loose from the joists is deflected by the weight of a person and rubs against the nails that hold it in place. The sub floor or joists may be bowed, and the nails also may be expelled from the wood during drying. Movement may occur between the joist and bridging or other floor members when one joist is deflected while the other members remain stationary. Gluing the sub floor is an acceptable method of code compliance in certain jurisdictions. Renailing floor joists with ring-shank nails will also substantially reduce severe floor squeaks. Because the performance guideline requires The Bolster Contractor to make a reasonable attempt to eliminate squeaks without requiring removal of floor and ceiling finishes, nailing loose sub flooring with casing nails into the carpet surface and countersinking the head is an acceptable practice.

 

3-3-2

Observation: Sub floor is uneven.

Performance Guideline: Floors shall not have more than a ¼-inch ridge or depression within any 32-inch measurement. Allowable floor and ceiling joist deflections are governed by the local approved building codes. Measurements should not be made at imperfections that are characteristic of the code-approved material used. This guideline does not cover transition points between different materials.

Corrective Measure: The Bolster Contractor will correct or repair to meet the performance guideline.

 

3-3-3

Observation: Sub floor is out of square.

Performance Guideline: The diagonal of a triangle with sides of 12 feet and 16 feet along the edges of the floor shall be no more than ½ inch plus or minus 20 feet.

Remodeling Specific: The owner and The Bolster Contractor may agree to build a wood floor out of square in order to match or otherwise compensate for pre-existing conditions.

Corrective Measure: The Bolster Contractor will make the necessary modifications to any floor not complying with the performance guideline for squareness. The modification will produce a satisfactory appearance and may be either structural or cosmetic.

Discussion: Squareness is primarily an aesthetic consideration. Regularly repeated geometric patterns in floor and ceiling coverings show a gradually increasing or decreasing pattern along an out of square wall. The guideline tolerance of plus or minus ½ inch in the diagonal allows a maximum increasing or decreasing portion of about 3/8-inch in a 12-foot wall of a 12 x 16-foot room. However, The Bolster Contractor and client may agree to build an addition out of square in order to keep a new exterior wall on line with an existing wall of an out of square house. The corrective measure emphasizes the primarily aesthetic nature of squareness and makes the criteria for correction “a satisfactory appearance.” This criterion allows The Bolster Contractor to make either a structural change, if the defect is discovered in time, or some cosmetic change to hide the defect, if the construction is in the finishing stages when the defect is discovered.

 

3-3-4

Observation: A floor is out of level.

Performance Guideline: The floor should not slope more than l/2-inch in 20 feet. Crowns and other lumber characteristics that meet the standards of the applicable grading organization for the grade and species used are not defects. Allowable floor joist deflections are governed by the applicable building codes. Deflections due to overloading by the owner are not The Bolster Contractor's responsibility.  

Remodeling Specific: The Bolster Contractor and the owner may agree to build an addition out of level in order to keep the floor of an addition on the same plane, and the roof ridge on the same line, as those of an existing, out-of-level structure, or to compensate for some other pre-existing condition.

Corrective Measure: The Bolster Contractor will make a reasonable and cost-effective effort to modify the floor that does not comply with the performance guideline. Allowances should be allowed for shrinkage, cantilevers, and concentrated loads.

Discussion: Sloped floors have both an aesthetic and functional consideration. Measurements for slope should be made across the room, not in a small area.

 

3-3-5

Observation: Deflection is observed in a floor system constructed of wood joists, floor trusses, or similar products.

Performance Guideline: All wood I-joists and other manufactured structural components in the floor system and its components shall be sized and installed as provided in the manufacturers' instructions and code requirements.

Corrective Measure: The Bolster Contractor will reinforce or modify as necessary any floor component not meeting the performance guideline.

Discussion: Deflection may indicate an aesthetic consideration independent of the strength and safety requirements of the product. When an owner's preference is made known before construction, a higher standard may be agreed upon in writing by The Bolster Contractor and the owner.

 

3-3-6

Observation: Remodeling Specific: Wood flooring is not level at the transition of an existing floor to a room addition floor.

Performance Guideline: Flooring at a transition area shall not slope more than l/8-inch over 6 inches unless a threshold is added. Overall step-down, unless previously agreed upon with the owner, shall not exceed 1-1/8 inches. Variations caused by seasonal or temperature changes are not a defect.

Corrective Measure: The flooring transition shall be corrected to meet the performance guideline. The Bolster Contractor may add threshold or transition material, or pull up the flooring and reduce the high spot, or if possible, shim under new framing to bring floor within guideline.

Discussion: All wood members shrink and expand seasonally, with variations in temperature and humidity, and with aging. After installation, 2x dimensional lumber can shrink up to 1/2-inch. If the flooring, sub floor, or underlayment was not purposely overlapped onto the existing floor, the resulting irregularity is not a defect, but a natural result and characteristic of the wood's aging process. The drier the house becomes, the more shrinkage may be experienced. Either the old or the new floors may slope along the floor joist span. Joists in older homes may have deflected under load. This and other conditions may cause a hump at the juncture of the old to new.

 

3-3-7

Observation: Remodeling Specific: The floor pitches to one side in the door opening between the existing construction and the addition.

Performance Guideline: If the pitch is the result of the floor of the existing dwelling not being level, then in most situations a transition threshold may be the most appropriate and acceptable means of addressing the condition.

Corrective Measure: The Bolster Contractor will make a reasonable and cost-effective effort to meet the performance guidelines.

 

 

This post is intended for informational purposes only and is general in nature as it does not take into account your personal renovation situation. You should really consider whether the information is appropriate to your needs, and where appropriate, seek professional advice from a licensed architect, general contractor or financial / legal adviser. Bolster gratefully acknowledges the National Association of Home Builders (NAHB) in developing their Residential Construction Performance Guidelines for Professional Builders & Remodelers (Third Edition). Bolster's Quality Standards are closely modeled after the NAHB Guidelines but have been adjusted for local purposes.