Replacing Wood Treads And Risers

Procedure code:
643002S
Source:
Hspg Prepared For Nps - Sero
Division:
Wood and Plastics
Section:
Stairwork & Handrails
Last Modified:
07/18/2017

PART 1---GENERAL

1.01 SUMMARY

  1. This procedure includes guidance on removing and replacing damaged wood treads and/or risers.
  2. Wood stair treads and risers are very susceptible to damage because they are constantly exposed to wear.
  3. Exterior stairs are even more susceptible to damage because of exposure to the weather. Open joints and cupping of treads and risers may result from inadequate ventilation, preventing the sufficient evaporation of moisture.
  4. 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. Stair/Ramp Covering - Composed of the treads, risers, cove molding, nosing (molded or attached), and nosing return. The treads and risers can be connected by a butt joint, a rabbet joint, or a tongue-and groove joint.

1.03 SYSTEM DESCRIPTION

  1.  A wood stair covering in proper condition is free from decay and is structurally sound.
    1. The treads and newel must be rigid, the connections between all parts must be tight and sound, and all trim pieces must be present, undamaged, and adhered properly.
    2. The treads should have a slight descending pitch to ensure drainage.
    3.  The treads should have an integral front nosing.
    4. The underside of treads should have a routed drip so that water cannot enter the connection between tread and riser.
    5. The construction should have proper ventilation underneath to prevent cupping.

PART 2---PRODUCTS

2.01 MATERIALS

  1. Lumber for replacement risers and treads - treated with wood preservative
  2. Hardwood for wedges
  3. Wood scrap, same as tread (for assistance in placing wedge)
  4. Nails
  5. Caulk
  6. Paint
  7. Wood glue

2.02 EQUIPMENT

  1. Hack saw
  2. Pry bar and putty knives for trim removal
  3. Utility saw
  4. Pencil, square, and straight edge for marking
  5.  Hammer and block
  6.  Chisel
  7. Rooter
  8. Saw (for wood cuts)
  9. Drill
  10. Keyhole saw
  11. Screwdriver
  12. Knife to cut wedge excess

PART 3---EXECUTION

3.01 EXAMINATION

  1. Inspect for paint that is worn, chipped, peeling, blistered, or flaking.
    1. A proper paint seal is imperative to the protection of the wood from decay. If paint is peeling, decay may already be underway.
    2. Probe the wood with an ice pick to determine the existence of rot.
  2.  Inspect for wear in the surface such as chips or gouges. If the wear is minimal, holes can be filled and the surface restored.
  3. Inspect for the signs of insect infestation such as mold, fungus, bore holes, and sawdust piles.

3.02 PREPARATION

  1. Surface Preparation:
    1. Waterproof or treat wood with preservative and back prime all pieces before installation paying particular attention to the end grain. See procedure 06310-01-P for guidance on applying a water-repellant preservative.
    2. To replace damaged wood treads and risers, match existing depth.
    3. Reproduce the joint technique of the original; butt joints are easier to repair but dadoed joints are stronger and resist movement.

3.03 ERECTION, INSTALLATION, APPLICATION

  1.  If underside of tread is salvageable:
    1. Carefully remove tread and use underside as new top surface.
      1. If tread and riser are butt jointed:
        1. Pry off nosing return and cove molding return.
        2.  Remove balusters by sliding them out of slot in tread and pull down from hole in handrail.
        3. Pry off cove molding from under front of tread and carefully begin prying tread from riser below. Pry only enough to insert utility saw blade.
        4. Pry tread from riser below and cut nails with saw. Pull tread free from above starting at outside edge.
      2. If tread and riser are dadoed:
        NOTE: THE RISER MUST BE SACRIFICED.
        1. Drill holes at base of riser above tread and cut along joint with saw blade.
        2.  Pull tread free from above by starting at outside edge.
        3. Cut and properly fit new riser. Glue in new wedge below riser position at inside stringer. Replace riser and toenail into inside stringer from behind.
    2. Turn tread over and mark 45 degree miter for nosing return on outside corner. Measure old baluster position and mark inside new miter line. Cut out miter and baluster positions.
    3. Make angled cut at inner corner at new outside edge to accommodate angle of stringer.
    4. Fit scrap, same width and thickness as tread, into inside stringer. Fit new wedge underneath accordingly and remove scrap.
    5. . With hammer and block, knock tread with glued inner edge into position and nail tread to top of outer stringer.
    6. Replace balusters, nosing return, and cove molding. When replacing nosing return, glue only miter and adjacent surface to allow for expansion between pieces.
  2. If underside of tread is NOT salvageable:
    1. Remove nosing return, cove molding, and balusters as above.
    2. Drill starting holes through tread to cut it into thirds. Saw across tread in two places; nick risers, but, do not damage surface of risers.
    3. Remove center portion of tread by driving chisel into tread over riser to break off nosing of tread. Do not damage possible riser tongue. With chisel turned sideways, remove remaining tread section. Remove protruding nails.
    4.  On new tread, measure old baluster position and mark inside new miter line. Cut out miter and baluster positions.
    5. Make angled cut at inner corner at new outside edge to accommodate angle of stringer.
    6.  Fit scrap, same width and thickness as tread, into inside stringer. Fit new wedge underneath accordingly and remove scrap.
    7. With hammer and block, knock tread with glued inner edge into position and nail tread to top of outer stringer.
    8. Replace balusters, nosing return, and cove molding. When replacing nosing return, glue only miter and adjacent surface to allow for expansion between pieces.
  3. If underside of stair is accessible:
    1. Remove wedges from tread/stringer and riser/stringer connections.
    2. Remove screws or nails that connect tread to riser.
    3. With chisel, force riser down from tread. With hammer and block, tap tread back from front.
    4. Cut and fit new tread or riser to match original in size and thickness. Hold tread and riser together temporarily with nail.
    5.  Drive vertical wedge in behind riser at stringer. Cut off wedge excess flush with bottom of tread. Remove nail. Drive glue-soaked horizontal wedge in below tread. Chisel off excess wedge flush with stringer.
    6. At 6" from each end, drill pilot holes and drive screws through riser above center of tread.
  4. Additional Instructions for Exterior Stairs:
    1. Rout a rounded drip edge into the bottom of the tread so that water will not enter the joint between the tread and the riser below.
    2. Make the tread nosing integral with the tread.
    3. Prime all bare wood, using primer compatible with top coat. For redwood or cedar, use a latex primer containing a dye reactant. Prime edges, ends and both sides.
      NOTE: Treated lumber containing creosote, pentachlorophenol or other oily preservative solutions cannot be painted. Lumber treated with waterborne salts can be painted or stained.
    4.  Caulk all joints to seal out moisture.
    5. Apply top coats of paint compatible with prime coat.

3.04 ADJUSTING/CLEANING

  1. Shrinking may occur within a year. Repair may involve minor filling and repainting.

END OF SECTION

Last Reviewed 2017-07-18