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Historic Preservation - Technical Procedures

Spectitle:

Repairing Small Holes And Cracks In Wood Floors

Procedure code:

0956002R

Source:

Hspg Prepared For Nps - Sero

Division:

Finishes

Section:

Wood Strip Flooring

Last Modified:

02/24/2012

Details:

Repairing Small Holes And Cracks In Wood Floors



REPAIRING SMALL HOLES AND CRACKS IN WOOD FLOORS


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on filling small holes
         and surface cracks in wood floor boards and filling
         cracks between wood floor boards.

    B.   Cracks the thickness of a dime between floor boards is
         not uncommon.  In fact, plank boards may expand and
         contract 2-1/2 times that distance.

    C.   Cracks can develop between boards from what is known as
         compression shrinkage or compression set.  As the wood
         absorbs moisture, the floor boards swell.  For those
         boards that swell beyond their allowable range, the
         boards compress against one another and, sometimes,
         become damaged.  As the moisture level drops, the boards
         shrink and a gap develops between the boards.

    D.   See 01100-07-S for general project guidelines to be
         reviewed along with this procedure.  These guidelines
         cover the following sections:

         1.   Safety Precautions

         2.   Historic Structures Precautions

         3.   Submittals

         4.   Quality Assurance

         5.   Delivery, Storage and Handling

         6.   Project/Site Conditions

         7.   Sequencing and Scheduling

         8.   General Protection (Surface and Surrounding)

         These guidelines should be reviewed prior to performing
         this procedure and should be followed, when applicable,
         along with recommendations from the Regional Historic
         Preservation Officer (RHPO).

1.02 DEFINITIONS

    A.   A wooden floor surface can be either a series of
         connected planks or parquet (small wood pieces arranged
         in decorative patterns). The wood used is either plain
         sawn or quarter sawn. Plank flooring, the more common
         type, is assembled by joining: butt joint, tongue and
         groove, shiplap, doweled, spline. Wood floors are usually
         secured to the under structure by countersinking nails,
         blind-nailing, or screwing and plugging.


PART 2---PRODUCTS

2.01 MANUFACTURERS

    A.   Abatron, Inc.
         5501 95th Ave.
         Kenosha, WI  53144
         800/445-1754 or 414/653-2000

2.02 MATERIALS

    A.   Commercial wood putty, colors-in-oil or oil stain pigment
         to color putty to match (Abatron, Inc., Allied Resin
         Corp., or approved equal) - available in wood tones

    B.   Wood glue to reattach splinters

    C.   Sandpaper

    D.   Sawdust

    E.   Varnish

    F.   Shellac

    G.   White wood glue

    H.   Tissue paper

    I.   Calcined magnesia

    J.   Strips of cloth, grey felt weatherstripping or varnished
         hemp, marine caulking compound

    K.   Linseed oil

    L.   Wood for shims (do not use shingles, they lack
         compressive strength)

    M.   Strips of wood for nailing to underside of floorboards or
         for filling cracks between boards

2.03 EQUIPMENT
   
    A.   Small putty knife

    B.   Brush or sponge to spread pigment

    C.   Hammer

    D.   Nails

    E.   Screwdriver

    F.   Stiff bristle brush

    G.   Vacuum


PART 3---EXECUTION

3.01 EXAMINATION

    A.   Inspect for the signs of decay or insect infestation such
         as mold, fungus, bore holes, and sawdust piles.

3.02 ERECTION, INSTALLATION, APPLICATION

    A.   For Small Holes and Surface Cracks:

         1.   Fill with commercial wood putty:

              a.   Stain the putty to match the floor by using
                   either colors-in-oils or the settled pigment
                   from the bottom of the stain can.

              b.   When staining putty to match wood, it is
                   better to go darker than the wood rather than
                   lighter.

              c.   When filling a hole or crack, add filler in
                   layers and allow drying time between layers.

         2.   If a floorboard is splintered, glue the splinter
              down and fill the crack.

         3.   If damage is such that it cannot be successfully
              filled and the board is relatively easy to remove,
              turn the board over rather than replacing it.  The
              new surface should be sanded to match surrounding
              boards and may need to be shimmed to make it level
              with the existing surface.

              NOTE:  THE FEASIBILITY OF THIS METHOD OF REPAIR
              WILL DEPEND UPON THE ORIGINAL INSTALLATION SYSTEM
              AND THE APPEARANCE OF THE UNDERSIDE OF THE WOOD
              FLOORING.

    B.   For Cracks Between Floorboards:  In general, it is best
         to leave cracks between boards alone.  Gaps often
         diminish as the boards expand in more humid seasons.
         However, there are several methods for filling cracks
         between floor boards:

         1.   If small, they can be covered with a new floor
              finish.  If the underside of the floorboards are
              exposed, nail strips of wood to the underside of
              the crack.

         2.   Fill with a paste filler (made by user):

              a.   Mix sawdust with varnish, shellac or white
                   glue, or

              b.   Mix tissue paper, glue size, and calcined
                   magnesia to a mass like putty.

              c.   Press mixture into crack using putty knife and
                   finish smooth so it is level with the floor
                   surface.

         3.   Fill with a fibrous filler (made by user):

              a.   Soak cloth strips in linseed oil or glue, or
                   use strands of hemp rope (grey felt
                   weatherstripping may also be used, but is not
                   as stainable as hemp rope).

              b.   Pack cloth strips or strands of rope (in
                   layers, if necessary) into the crack using a
                   screwdriver or putty knife.

              c.   If desired, stain the filler material to match
                   the floor.

         4.   Fill with caulking compound:

              a.   If the floor is to be painted, use marine
                   caulking compound to fill the crack. It will
                   expand and contract with the wood and the
                   paint will hide the color difference.

              b.   Carefully mask the area before caulking.

              c.   Fill crack using a caulking gun or similar
                   injection device.  It is best to fill the
                   crack at mid-cycle (in Spring or Fall).

              d.   Finish the surface level with the floor.

         5.   Fill with a thin strip of wood:

              NOTE:  This option is not ideal because it
              reintroduces the potential for compression problems
              resulting from wood expansion and contraction.
              However for large cracks that are hazardous:
         
              a.   Thoroughly clean the opening of dirt and
                   debris using a stiff bristle brush and vacuum.

              b.   Slip a thin strip of wood into the crack.
                   Match the depth of the surrounding floor and
                   stain to match.

              c.   Nail or glue the strip to only one side of the
                   crack to allow for expansion and contraction.

    C.   In extreme cases, the floorboards will have to be taken
         up and reinstalled (see 09560-01-R, "Replacing Damaged
         Floorboards" for guidance).

                             END OF SECTION