Repairing A Wobbly Or Broken Exterior Cast Iron Newel Post

REFERENCES:

Margot Gayle, David Look, John Waite. Metals in America’s Historic Buildings. Washington,DC: National Park Service, 1995.

L. William Zahner. Architectural Metals. New York: John Wiley & Sons, 1995.

PART 1–GENERAL

1.01 SUMMARY

1. This procedure includes guidance on repairing a wobbly or broken exterior cast iron newel post. THIS TYPE OF REPAIR SHOULD BE PERFORMED BY A PROFESSIONAL IRONWORKER.
2. A wobbly newel post may be caused by water from the setting concrete or stone, improper setting, and/or joints not caulked.

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).

4. For additional information on the characteristics, uses and problems associated with cast iron, see 05010-04-S; for guidance on inspecting cast iron failures, see 05010-01-S.

1.02 DELIVERY, STORAGE, AND HANDLING

1. Storage and Protection:
   1. Cast iron railing or balustrade should be stored as to protect from surface damage at all times, carefully packed and should remain so from the time of delivery until set. Keep uninstalled and unpainted metal materials in a dry, rust-free storage facility; surfaces to be welded are generally not primed.
   2. Salvaged historic material shall be carefully packed and stored under cover and in the building away from working or traffic areas. Mark salvaged material with the year of removal.

PART 2–PRODUCTS

2.01 MATERIALS

1. Molten lead or lead wool
2. Screws and bolts
3. Wiping cloths

2.02 EQUIPMENT

1. Wire brush - removes rust and flaking metal as well as loosened paint
2. Eye and skin protection
3. Heavy gloves and protective gear
4. Screwdriver
5. Welding equipment
6. Electric drill
7. Electric grinder

PART 3–EXECUTION

3.01 EXAMINATION

1. Before proceeding with steps to repair cast-iron newel post, it is important to first determine the cause and extent of the problem. Determine the age of the railing/balustrade and examine the condition of the entire surface. Inspect for:
   1. Joints - which are open or misaligned, thus allowing water into the railing or newel.
   2. Parts - which have failed or which are unsecured, broken, cracked, missing, distorted, or loose (check screws and bolts).
   3. Paint - coating failures such as chips, losses, peeling, checks, bubbling, and wear.
   4. Rust corrosion - caused by moisture including, sea water and sea air, deicing salts, acids and some soils.
   5. Galvanic corrosion - corrosion caused when iron is in direct contact with a dissimilar metal and is wetted by rain, fog, condensation, etc.
   6. Determine the source of the moisture which causes the deterioration.
   7. Determine if the railing/balustrade can be salvaged.
   8. Measure the dimensions of the various metal parts needing replacement.

3.02 ERECTION, INSTALLATION, APPLICATION

1. Repairing A Wobbly Newel Post: This can usually be repaired on site by a professional or in the shop by an ironworker.

   1. Reset the center rod in the base and weld small supports at the base of the newel.
   2. Drill holes in the masonry step or walk to correspond with the supports.
   3. Pour molten lead into the holes before setting the newel.
   4. Caulk all the joints and prime and paint the entire assembly. See 05010-13-S and 09900-07-S for guidance on painting cast iron.

   NOTE: IRON THAT IS SET IN CONCRETE OR STONE SHOULD BE PACKED IN LEAD TO PREVENT THE IRON FROM RUSTING. LEAD IS SOFT ENOUGH TO STILL ALLOW THE IRON TO MOVE.

2. Repairing Posts That Are Broken in Half: The posts must first be internally reinforced with steel pipes.
   1. Before attaching the elements, clean the surface of any traces of dirt, oil/grease stains, peeling paint, or rust. See 05010-05-R for guidance on cleaning cast iron.

   2. Weld the original elements of the posts back together, using a professional welder. Grind down any visible beads of welding material.

      NOTE: SUCCESSFUL WELDING OF CAST IRON CAN BE A RELATIVELY EXPENSIVE OPERATION.

      NOTE: WELDING OF CAST IRON IS VERY DIFFICULT TO DO IN THE FIELD. IT SHOULD BE EXECUTED ONLY BY A SKILLED WELDER UNDER CAREFUL SUPERVISION.

      CAUTION: DURING WELDING THE METAL BECOMES VERY HOT AND CAN UNDERGO TREMENDOUS THERMAL SHOCK. IT MAY RECRYSTALLIZE IF EXCESSIVE HEAT IS APPLIED.

      1. For large sections, welding should take place off site. The piece must be removed and transported to a workshop where it can be preheated before welding and postheated after welding to ensure a gradual temperature change within the metal.
         1. Advantages of welding:
            1. Arc welding produces a strong, durable connection and, if properly executed, is at least as strong as the surrounding metal.
            2. It is faster and less expensive than threaded connections, which require drilling a pilot and then tapping to accommodate screws or bolts.
            3. Welding is the most preferred for the attachment of the decorative castings and for other non-structural repairs for economic reasons and because it allows to preserve the original damaged elements, which otherwise would have to be replaced.
         2. Disadvantages of welding:
            1. In cases where the original attachments are bolted, the use of this method may result in internal stresses (welds cannot move with seasonal expansion/ contraction cycles) which may in turn lead to further breaks.
            2. Welding may leave a ‘bead’ along the surface of the connection which may be unacceptable in some restoration projects, even though much of the weld may later be ground down, depending on the location and the welding material.
            3. Metallic bond (gas) welding is more reliable than fusion (arc) welding in repairing large sections of cast iron, because a lower temperature is used and heat is applied and removed at a slower rate.