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Historic Preservation - Technical Procedures

Spectitle:

Epoxy Repair For Deterioration And Decay In Wooden Members

Procedure code:

0630001R

Source:

Hspg Prepared For Nps - Sero

Division:

Wood And Plastics

Section:

Wood Treatment

Last Modified:

02/24/2012

Details:

Epoxy Repair For Deterioration And Decay In Wooden Members



EPOXY REPAIR FOR DETERIORATION AND DECAY IN WOODEN MEMBERS


PART 1---GENERAL

1.01 SUMMARY

    A.   This procedure includes guidance on stabilizing decayed
         wood members with epoxy consolidant and filler.

    B.   Deterioration and decay in wood results from moisture
         infiltration, accompanying fungal growth and insect
         infestation.  Paint, caulk and sealant failures are also
         a major cause of wood deterioration.

    C.   Some sources of moisture may include the original
         moisture in green wood, rainwater, condensation, ground
         water, piped water, and water released by water-
         conducting fungus through the process of decay itself.

    D.   Epoxy repair may be appropriate if:
             
         1.   the piece to be repaired is historically
              significant.  Epoxy repair makes it possible to
              retain most of an original component by selectively
              repairing only the damaged area.

         2.   if the piece is decorative and replacement would be
              too expensive or impossible.

    E.   Epoxy repair may NOT be appropriate if:

         1.   the piece is a structural member.  Epoxy has
              adequate compression strength, but is not the best
              choice to repair a member in tension.  In this
              case, replacement is usually a better option.

         2.   the wood to be repaired is to remain unpainted, as
              the epoxy is quite different in appearance than
              wood.  In this case, the wood should be selectively
              replaced.

         3.   if the area to be repaired is large, as epoxy
              repair can be expensive.

    F.   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 MANUFACTURERS  

    A.   Conservation Services
         8 Lakeside Trail
         Kinnelon, NJ 07405
         201/838-6412

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

    C.   Roux Laboratories
         5344 Overmyer Dr.
         Jacksonville, FL  32205
         904/693-1200

2.02 MATERIALS

    A.   Epoxy consolidant and epoxy filler, both are multiple
         part compounds.  Purchase by the gallon unless a large
         amount of epoxying needs to be done.  Use one of the
         following, or approved equal:

         1.   "Con Serv (T) Flexible Consolidant 100"
              (Conservation Services):  Cures slowly with a 5 to
              7 hour application time to allow deep penetration.
              Complete hardness is achieved in 3 to 6 days.

         2.   "Con Serv (T) Flexible Patch 200" (Conservation
              Services):  A four part putty-like filler; Is not
              easy to mix in small amounts; Consistency and
              hardness are easily controlled with this material.

         NOTE:  The products of Conservation Services are
         recommended for treatment of thicker wood such as window
         sills.  Because of its slower curing time, it allows for
         deeper penetration into members.

         3.   "Liquidwood-1" Consolidant (Abatron):  Solidifies
              in a short period of time.

         4.   "Woodepox-2" Adhesive Paste (Abatron):  A two-part
              paste mix; final hardness is determined by varying
              the ratio of the two parts.  The LiquidWood can be
              used as a thinner, but this reduces the flexibility
              of the filler.

         NOTE:  These Abatron products are recommended for use on
         smaller members such as window sashes where deep
         penetration of consolidant is not required.  The quick
         drying feature is an advantage for small, but repetitive,
         jobs.  Abatron carries twenty different types of wood
         consolidants with varying degrees of penetration.

    B.   Oil clay that can be purchased from a hobby store -- used
         to keep consolidant from leaking through cracks.

    C.   Nitril Rubber Gloves (Abatron)

    D.   Disposable vinyl gloves:  Available from drug store or
         pharmaceutical supply distributor in 50 count or larger
         boxes.

2.03 EQUIPMENT

    A.   Plastic bottles, like those used for hair dye, to apply
         the consolidant; having many on hand is recommended.
         Cleaning of the bottles for reuse is possible.

    B.   Applicator bottles:  Available from drug store and sold
         for hair dye application usually in 8 fl. oz. size;  Also
         available in bulk from Roux Laboratories.  Roux Color
         Applicators lend themselves more easily to cleaning and
         reuse.

    C.   Rags of different sizes to wipe up spills before epoxy
         has a chance to harden, small rags are recommended for
         quick one time uses such as wiping off spouts and caps.

    D.   Thin wooden sticks, approximately 8" long for scooping
         out paste and mixing consolidant.

    E.   Goggles and a respirator for protection from fumes.

    F.   Putty knives for application of filler

    G.   Channel lock pliers for opening stuck caps

    H.   Allen wrench to clean out cap holes

    I.   Needle nose pliers to pull out hardened epoxy

    J.   1/8"x8"x12" Masonite boards for mixing paste filler

    K.   Carbon dioxide fire extinguisher:  Curing epoxy creates
         heat that may cause fire

    L.   Rotary saw

    M.   Air compressor

    N.   Drill

    O.   Stiff bristle brushes


PART 3---EXECUTION

3.01 EXAMINATION

    A.   Detect rot using the "Pick Test":

         1.   Insert an ice pick into the wood at a slight angle.

         2.   Lift the pick out.  If the wood splinters in long
              pieces, the wood is ok.  If the wood snaps where
              the pick is being lifted, the wood is decayed.

    B.   When rot is discovered:

         1.   Determine the source of moisture infiltration and
              eliminate it.  

              a.   If rot is only present on the surface, drying
                   is all that is necessary to stop the spread of
                   decay and kill off any growth.

         2.   If source of moisture is unknown, treat the wood
              with a preservative.  

              a.   Preservatives are caustic chemicals and should
                   be handled with care.

              b.   A particularly dangerous wood preserving
                   chemical is pentachlorophenol (a.k.a. penta).
                   CAUTION:  THIS CHEMICAL IS CARCINOGENIC AND
                   ITS USE IS BANNED IN MANY STATES.

         3.   Preservatives will eliminate fungal growth, but
              generally do not restored strength to the
              deteriorated wood material.  

3.02 PREPARATION

    A.   Surface Preparation:

         1.   Dry affected wood member completely to arrest
              further decay.  Dry in place if possible -or-
              remove the member and keep in a cool dry place
              until dry.

              CAUTION:  IF THIS PRECAUTION IS NOT TAKEN, THE
              EPOXY CAN ACTUALLY TRAP MOISTURE IN WOOD FIBERS AND
              ACCELERATE THE DECAY PROCESS.

         2.   Have all materials at hand before the mixing
              process begins.

         3.   Label all caps and lids so that a cap or lid is not
              placed on the wrong container or it may remain
              there permanently.

3.03 ERECTION, INSTALLATION, APPLICATION

    CAUTION:  AS EPOXIES CURE, HEAT IS PRODUCED.  FOR THIS REASON,
    EPOXIES SHOULD BE USED IN SMALL QUANTITIES TO DETER EXTENSIVE
    HEAT BUILD-UP.  CARE SHOULD BE TAKEN WHEN USING EPOXY ON A HOT
    DAY.

    A.   Repair decayed wood using epoxy wood consolidant:

         1.   Drill 1/4" or 3/16" holes in affected wood to
              receive epoxy consolidant:

              a.   Drill holes at an angle and spaced
                   approximately 2" on center in staggered rows.
                   The top of one hole should line up with the
                   bottom of the next hole.  

                   CAUTION:  BE SURE NOT TO DRILL THROUGH THE
                   ENTIRE SURFACE FOR CONSOLIDANT WILL LEAK OUT
                   FROM BEHIND.

              b.   Dam any surface cracks with oil clay so that
                   epoxy will not leak.

         2.   Remove sawdust and dirt from drilled holes using
              compressed air or stiff bristle brushes.

         3.   Following manufacturer's instructions, mix a small
              amount of the consolidant components (resin and
              hardener) together in an applicator bottle.  Stir
              the mixture thoroughly by hand with a thin stick
              for 4 minutes or with a bent coat hanger chucked
              into a drill for 2 minutes.

         4.   Using a large plastic syringe or squeeze bottle and
              tube spout, carefully squirt the consolidant into
              the pre-drilled holes.  Completely saturate the
              wood, moving from hole to hole refilling until the
              wood can hold no more.  More than one application
              may be needed.

         5.   Wipe off any excess consolidant or spills and cover
              the treated area to protect until cured as directed
              by epoxy manufacturer.

         6.   If severed pieces need to be re-attached, glue them
              in place with a mixture of consolidant and filler.

    B.   When the consolidant has cured, fill the voids in the
         surface with epoxy filler (wood-epoxy putty):

         1.   Mix the two part epoxy filler following the same
              procedures for mixing consolidant in Section 3.03
              A.3. above.  Mix filler to achieve the consistency
              of a glazing compound that can be worked with a
              putty knife.

         2.   Apply the filler to the surface:

              a.   For large voids, apply filler in 1" thick
                   layers.  This reduces the possibility of
                   problems associated with heat build-up.

              b.   Build up filler layers slightly above the wood
                   surface to allow for planing and sanding
                   smooth after it has cured.

         3.   When the filler has cured, sand or plane the
              surface smooth.  

         4.   Apply a wood preservative to surrounding wood
              surfaces and prime and paint the entire surface.

                         END OF SECTION