Stabilizing A Sagging Wood Stair

PART 1–GENERAL

1.01 SUMMARY

1. 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.
   
2. A stair may noticeable sag as a result of building settlement, poor original construction, or shrinking and warpage in wood.
3. 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

1. A Stair is composed of stringers, either open, housed, or skirted; carriage; kick plate (a.k.a. scantling block); newel base; and the cleats.
2. 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

1. Replacement 1x6 stock for cleats
2. Nails
3. Materials for removing and replacing plaster (see 09210-03-R)

2.02 EQUIPMENT

1. Equipment for removing and replacing plaster (see 09210-03-R)
2. Claw hammer

PART 3–EXECUTION

3.01 EXAMINATION

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

3.02 ERECTION, INSTALLATION, APPLICATION

1. 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.
2. 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?
3. Reattach any loose cleats and replace missing or damaged cleats with new stock. Attach tight with underside of tread and back of riser.
4. If cleats are nailed to only one side of carriage, remove every other one and attach to other side of carriage to distribute load.
5. Replace ceiling surface below as required. See 09210-03-R for guidance on replastering.