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Historic Preservation - Technical Procedures

Spectitle:

Stabilizing A Sagging Wood Stair

Procedure code:

0643005R

Source:

Hspg Prepared For Nps - Sero

Division:

Wood And Plastics

Section:

Stairwork & Handrails

Last Modified:

02/24/2012

Details:

Stabilizing A Sagging Wood Stair



STABILIZING A SAGGING WOOD STAIR


PART 1---GENERAL

1.01 SUMMARY
   
    A.   This procedure includes guidance making minor repairs to
         a sagging stair by repairing and/or replacing cleats -
         typically 1x6 wood boards that support the center of the
         treads.

         NOTE:  CLEAT REPLACEMENT MAY BE PERFORMED BY A NON-
         PROFESSIONAL; HOWEVER, THIS PROCEDURE REQUIRES THE
         REMOVAL OF THE CEILING SURFACE BELOW THE STAIR IN
         QUESTION.  THEREFORE, THIS WORK SHOULD BE EXECUTED BY AN
         EXPERIENCED CONTRACTOR.

         NOTE:  ALMOST ALL STRUCTURAL STAIR REPAIR INVOLVES THE
         REMOVAL OF THE CEILING SURFACE UNDER THE STAIR.  MAJOR
         STRUCTURAL REPAIRS MAY REQUIRE BRACING AND DISASSEMBLY OF
         STAIR AND SHOULD BE LEFT TO PROFESSIONALS.

    B.   A stair may noticeable sag as a result of building
         settlement, poor original construction, or shrinking and
         warpage in wood.  

    C.   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 Stair is composed of stringers, either open, housed, or
         skirted; carriage; kick plate (a.k.a. scantling block);
         newel base; and the cleats.  

    B.   Cleats - Cleats are used to stabilize the stair when the
         carriage is not notched to receive treads and risers.  
         Cleats are usually 1x6s nailed to the carriage and rise
         to support the center of treads.


PART 2---PRODUCTS

2.01 MATERIALS

    A.   Replacement 1x6 stock for cleats

    B.   Nails

    C.   Materials for removing and replacing plaster (see 09210-03-R)

2.02 EQUIPMENT

    A.   Equipment for removing and replacing plaster (see 09210-03-R)

    B.   Claw hammer


PART  3---EXECUTION

3.01 EXAMINATION

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

3.02 ERECTION, INSTALLATION, APPLICATION

    A.   Carefully remove ceiling surface under the stair in
         question.  This usually entails removal of all plaster
         and lath.  See 09210-03-R for guidance in removing
         plaster.

    B.   After exposing structure from below, check condition of
         possible cleats.  

         1.   Are any cleats missing?  

         2.   Are any pulled away or loose?  

         3.   Are cleats all nailed to the same side of carriage?

    C.   Reattach any loose cleats and replace missing or damaged
         cleats with new stock.  Attach tight with underside of
         tread and back of riser.

    D.   If cleats are nailed to only one side of carriage, remove
         every other one and attach to other side of carriage to
         distribute load.

    E.   Replace ceiling surface below as required.  See 09210-03-R
         for guidance on replastering.

                         END OF SECTION