Skip to main content

Historic Preservation - Technical Procedures

Spectitle:

Replacing A Damaged Subfloor Under Tongue And Groove Wood Flooring

Procedure code:

0955003R

Source:

Hspg Prepared For Nps - Sero

Division:

Finishes

Section:

Wood Flooring

Last Modified:

02/24/2012

Details:

Replacing A Damaged Subfloor Under Tongue And Groove Wood Flooring



REPLACING A DAMAGED SUBFLOOR UNDER TONGUE AND GROOVE WOOD
FLOORING


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedures includes guidance on replacing a damaged
         subfloor under tongue & groove flooring.

    B.   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).


PART 2---PRODUCTS

2.01 MATERIALS

    A.   Replacement subfloor board

    B.   Nails

    C.   Wood blocking for board support at joist

    D.   Hardwood shims (if required)

    E.   Construction grade plywood for complete subfloor
         replacement (thickness to match existing condition)

2.02 EQUIPMENT

    A.   Prybar

    B.   Wide blade putty knives

    C.   Carpenter's nippers to remove nail heads

    D.   Hammer for baseboard and finished floor removal

    E.   Saw to cut damaged subfloor board

    F.   Drill to make pilot hole for saw

    G.   Tools for accurate measurement


PART 3---EXECUTION

3.01 EXAMINATION

    A.   Check for problems caused by decay:  Signs of a decayed
         subfloor include buckling or discoloration of the
         finished floor, a spongy texture underfoot, water stains
         on the subfloor as seen from the underside, and general
         dampness.

    B.   Probe the wood with an ice pick to determine the
         existence of rot.

    C.   Inspect for signs of insect infestation such as mold,
         fungus, bore holes, and sawdust piles.

    D.   Documentation:  Photograph existing condition of flooring
         including pattern, etc. for ease of reinstallation.

3.02 PREPARATION

    A.   Protection:  Adjacent surfaces and permanent equipment
         must be masked or covered during repair and maintenance.
         Coverings must be adhered without adhesive tape or nails.
         Impervious sheeting that produces condensation shall not
         be used.

    B.   Surface Preparation:

         NOTE:  THE COMPLETE REMOVAL OF THE FINISH FLOOR MATERIAL
         IS ONLY REQUIRED WITH INTERLOCKING FLOOR ASSEMBLIES SUCH
         AS TONGUE & GROOVE.

         1.   Before replacing the subfloor, carefully remove the
              baseboard and the finished floor, label and set
              aside for reinstallation.

              a.   As each piece is removed, mark it as to its
                   original location; during storage, organize by
                   location to ease reinstallation.

              b.   Remove shoe molding of baseboard first, using
                   gentle pressure on a pry bar at nail
                   locations.  Hold gaps open with blocking as
                   work progresses along the length of each trim
                   piece.

              c.   Next, remove baseboard, beginning with top
                   moldings which are often separate from the
                   broad, flat sections.  Remove it like the shoe
                   molding, applying pressure only at nail
                   locations until all nails are exposed and the
                   trim pieces can be removed.

              d.   To remove nails, pull them out from the back
                   of the board; cut nail heads first, if
                   required.

         2.   When removing the floorboards, find the last board
              laid.  Remove it and work in reverse of the manner
              in which the floor was installed.

3.03 ERECTION, INSTALLATION, APPLICATION

    A.   Partial subfloor replacement:  Cut damaged subfloor board
         off at nearest joist.  Nail block to joist for new board
         support.

         1.   Carefully measure the new board and do a trial
              fitting.  Shim or rip as required to level the new
              board with the surrounding ones.

         2.   Facenail the new subfloor board to the joist or the
              attached support block.

         3.   When repair is complete, reinstall finished floor
              and baseboards to match historic condition.

    B.   Full subfloor replacement:  If the subfloor warrants
         complete replacement, consider 1" construction grade
         plywood.  It provides a strong and dimensionally stable
         subfloor with no squeaks.

                             END OF SECTION