The inspector should be familiar with the interior framing in a home. Even with solid masonry outer walls, the home has interior wood framing defining walls, ceilings, and floors.
Floors
Most homes have a 2-layer floor, consisting of
a subfloor and a finish floor above it. In balloon framing, the
subfloor goes to the inner edge of the wall stud. In platform framing, the subfloor goes under the sole plate and to the exterior.
The subfloor today is normally
plywood, OSB, or
particle board sheets 5/8” to 3/4” thick, laid either
perpendicular or diagonally to the joists. If the subfloor is laid on the perpendicular, the finish floor is then laid parallel to the joists. If the subfloor is on the diagonal, then the finish floor is laid either perpendicular or parallel to the joists.
Guide Note
Pages 83 to 88 present
information about the interior framing of a home. The inspection and reporting of interior walls, ceilings, and floors is covered in another of our guides — A Practial Guide to Inspecting Interiors,
Insulation, Ventilation. Use these pages to learn about construction techniques.
Joist extended and nailed to stud Sill Stud Wall Finish Finish Flooring Floor Joist Subflooring Balloon Framing Sill Header Subflooring Sole Plate Floor Joist Wall Finish Finish Flooring Stud
Joist butted against header and nailed
Platform Framing
Subflooring Perpendicular, Finish Flooring Parallel
Subflooring Diagonal, Finish Flooring Parallel or Perpendicular Joists
Subflooring Flooring
Joist extended and nailed to stud Sill Stud Wall Finish Finish Flooring Floor Joist Subflooring Balloon Framing Sill Header Subflooring Sole Plate Floor Joist Wall Finish Finish Flooring Stud
Joist butted against header and nailed
Platform Framing
Subflooring Perpendicular, Finish Flooring Parallel
Subflooring Diagonal, Finish Flooring Parallel or Perpendicular Joists Subflooring Flooring Sill Header Subflooring Sole Plate Floor Joist Wall Finish Finish Flooring Stud
Joist butted against header and nailed
The meeting edges of the plywood or particle board sheets are nailed to the joists. A structural adhesive may be applied to the joists to add strength to the connection.
Some subfloors are made with tongue and groove planking. The home inspector can determine whether this is
true by examining the subfloor from the basement. In some cases, you may find that there is no subfloor under a hardwood finish floor. This is common in earlier buildings or in newer buildings where the builder just hasn’t put a subfloor in under a hardwood floor.
The top layer of flooring may be one of the following:
• Hardwood: Tongue and groove strips from 1 3/4” to 2
1/4” wide, usually made of oak. But birch, beech, chestnut, maple, pecan, walnut, or hard pine can be used. Strip flooring is usually nailed. If no subfloor is put in, the strips should be at least 1 1/2” thick.
• Softwood: 1 x 4 tongue and groove strips, usually pine,
although fir and cedar may be used.
• Underlayment: 1/4” plywood or particle board sheets are
often used over the subfloor when the floor is expected to be finished with carpeting or resilient coverings such as linoleum or vinyl.
• Ceramic tile, stone, marble, slate: When these tiles are
used, they are laid in a bed of mortar or adhesive on the subfloor or on a plywood underlayment. If no
underlayment is used, the subflloor should be 3/4” thick to carry the weight of the tiles.
NOTE: Finish flooring may be applied to the concrete floor in slab on grade construction.
The problems we’ve already discussed relating to beams and joists (starting on page 54) can have a detrimental ef fect on the floor itself. Deterioration of girders and joists, cracking, sagging, twisting, rot, improper notches or cuts in these members, and loss of connection and/or support can all contribute to an abnormal condition in the floor. Here is an overview of signs the inspector may encounter in floors that indicate structural problems:
Uneven floors: A floor can have highs and lows in it. A hollow can be caused by the failure of a single joist. When a
hollow is present in the floor along a partition, it may be
Worksheet Answers(page 82)
1. A is Figure #3. B is Figure #2. C is Figure #4. D is Figure #8. E is Figure #5. F is Figure #1. G is Figure #6 H is Figure #7. 2. Bracing (Girt) 3. Flashing 4. Ledger
5. Metal (brick) ties 6. Air space
that the partition is built between the joists. When the hollow appears on either side of a doorway, it’s an indication of poor support for the studs on either side of the opening. Aridgein
an upstairs floor may be caused by a downstairs partition built parallel to a joist. There may be a bulgein the floor over a
support column, indicating that the column is moving up or the house is moving down. Another cause of a bulge can be from an overloaded cantilevered joist, where the joist’s interior end is being forced upward.
• Unlevel floors: Unlike uneven floors, an unlevel floor has
a continuous slope in one direction. This can be caused by foundation settlement pulling the floor lower at the outer edges. The condition can also be caused by shrinkage of wood members, where interior walls will shrink more than the outer wood framing. In this case, floors are likely to tilt inward toward partitions.
• Sagging floors: This is where there is a low area in the
middle of a room. This is largely due to overloading the floor without the proper supports being added to prevent the sag. Waterbeds, refrigerators, pianos, and other heavy objects can cause floor sag. More support is needed.
• Deflecting floors: These floors have upward and
downward movement. Bouncy floorsare usually due to
weakness in the joists or a lack of proper bridging. Softor springy floors can indicate a problem between the
subfloor and joists — poor support of the subfloor by the joists because of poor nailing or loss of connection. Improper spanning are also causes of the above.
• Noisy floors: Squeaksin flooring are caused by a poor
connection between the subfloor and the joists. Weight on the floor pushes the subfloor down to the joist, and the resulting squeak is caused by nails sliding in and out. The home inspector may notice drumming and rattling soundsfrom the floor. These sounds are associated with
the joists, not the subfloor. Low frequency sounds can be caused by weak flexible floor joists. Higher frequencies are the result of stiffness in the joists.
PROBLEM SIGNS • Uneven floors • Unlevel floors • Sagging floors • Deflecting floors • Noisy floors Guide Note
In slab on grade construction, the floor can indicate problems with the slab (see pages 70 and 71 of this guide).