Historic Preservation - Technical Procedures
- Securing An Exterior Wooden Balustrade
- Procedure code:
- Hspg Prepared For Nps - Sero
- Wood And Plastics
- Stairwork & Handrails
- Last Modified:
- Securing An Exterior Wooden Balustrade
- Last Modified:
SECURING AN EXTERIOR WOODEN BALUSTRADE
A. This procedure includes guidance on repairing a wooden
balustrade, including the handrail, the footrail and the
B. An exterior wooden balustrade system is particularly
susceptible to decay for a number of reasons:
1. Individual members are usually ornamentally turned
or carved, exposing a large degree of end grain in
proportion to the size of the member to wear and
2. The handrail takes all the weight from forces
applied to the balustrade. It is usually connected
to a column or post with a butt joint which does
not allow for the transfer of any load to the
column and exposes the end grain to weather;
therefore, making this joint highly prone to
moisture infiltration and the handrail to decay.
3. Decay in a baluster typically occurs at the joints,
particularly at the footrail if the top surface of
the footrail is not sloped to shed water.
4. Decay may also occur in the footrail if the bottom
surface is too close to the ground. If the
footrail is not adequately supported, the entire
balustrade assembly will sag.
A. Balustrade - The components consist of the handrail,
footrail and balusters. The handrail and footrail are
joined at the ends to a column or post. The balusters
are vertical members that connect the rails.
1.03 SYSTEM DESCRIPTION
A. A wooden balustrade in proper condition is rigid and free
from decay. It is designed with sloping surfaces to repel
water and has properly caulked, tight joints.
A. Periodically (late spring and late fall) inspect and
B. Check condition of caulking and replace as necessary.
C. Clean with a mild soap and water and scrub with a soft
bristle brush. Do not allow cleaning solution to remain
on surface for more than 10 minutes.
D. Rinse surface thoroughly with clear water twice. Corners
should be scrubbed with a tapered-end hand brush or hand
held mop strands.
E. Use sponge along with clean water to rinse. Remove
streaks with a damp chamois and water.
F. Remove mildew, moss, fungal growth, and vegetation with
a 50/50 mixture liquid bleach and water. Scrub with a
natural or nylon bristle brush and rinse thoroughly.
A. Wood screws
B. Galvanized finish nails
C. Replacement baluster
D. Wood dowels
E. Mild soap
F. 5% liquid bleach solution
G. Clean, potable water
A. Ice pick (for determining the presence of decay)
B. Waste container
C. Corn broom
D. Dust pan
E. Supply of treated rags
F. Wood glue
J. Chisel for mortising
K. Wood blocking
L. Replacement piece (if needed)
M. Two buckets (for extra solution and rinse)
N. Two sponges (for solution and rinse)
O. Brushes and string mop
P. Supply of dry wiping cloths and chamois
Q. Broom and garden sprayer
A. Regularly inspect for dirt build-up. Cleaning should be
done regularly, see Section 1.04 above for maintenance
1. Inspect for paint that is worn, chipped, peeling,
blistered, or flaking. A proper paint seal is
imperative to the protection of the wood from
decay. If paint is peeling, decay may already be
2. Probe the wood with an ice pick to determine the
existence of rot.
3. Inspect for the signs of biological attack and
insect infestation such as mold, fungus, bore
holes, and sawdust piles.
1. Mask or cover adjacent surfaces and permanent
equipment during repair and maintenance. Coverings
must be adhered without adhesive tape or nails.
Impervious sheeting that produces condensation
shall not be used.
2. Protect landscape work adjacent to or within work
area. Protect tree trunks with plank barriers. Tie
up spreading shrubs. Protective covering must allow
plants to breathe and be removed at end of the work
day. Scaffolding legs must be placed away from
plants. Plants cannot be pruned without prior
approval of historic architect or horticulturist.
3. Scaffolding, ladders, and working platforms shall
not be attached in any way to building. If ladder
must lean against building, legs shall be covered
with fabric so as not to mar surface of building.
3.03 ERECTION, INSTALLATION, APPLICATION
A. Repairing a Handrail - Where the handrail is connected to
the column with a butt joint, it may be re-attached and
secured in a series of different ways:
1. If wood is still relatively sound:
a. Drill pilot holes to avoid splitting the wood
b. Toenail the handrail back in place. Use
galvanized finish nails because they are more
weather resistant and grip the wood better.
NOTE: THIS IS THE LEAST EFFECTIVE METHOD OF
2. If enough wood is present to accept a screw,
toescrew the handrail back in place. Use a
galvanized, bronze, or stainless steel screw.
Countersink it and plug the hole before painting.
NOTE: THIS METHOD OF REATTACHMENT IS BETTER THAN
TOENAILING. THE SCREW HAS THE ABILITY TO DRAW THE
MEMBERS TOGETHER AND HOLD THEM THERE.
3. Install a kneelplate to secure the handrail in
a. Cut a kneelplate from extruded angle metal or
barstock or purchase as a prefabricated corner
b. Mortise it into the end of the rail.
c. Position it and screw it in place on the post.
d. Lower the handrail down over the kneelplate
and adhere the kneelplate to the bottom of the
rail with a screw.
B. Repairing a Loose Baluster:
NOTE: BALUSTERS ARE USUALLY SECURED BY TOENAILING.
1. Remove nail and secure with a screw. Countersink
screw and plug hole. If baluster can be rotated,
it can be secured with a dowel screw (threaded at
2. If top and bottom of baluster are the same and
baluster bottom is decayed while the top is sound,
baluster can be inverted with the appropriate filler to repair the baluster bottom.
3. If baluster is ornately carved, try using epoxy
NOTE: EPOXY CONSOLIDANT SHOULD BE CONSIDERED WHEN
WORKING WITH HISTORIC MATERIALS SINCE EPOXIES
ENABLE ONE TO SAVE AS MUCH OF THE ORIGINAL MATERIAL
4. If baluster has a square cut end, a replacement can
be made for the end only and connected to the
existing baluster with a wood dowel and glue.
5. If baluster must be replaced, use wood of the same
species and age as original if possible. Replicate
original exactly and install as original was
C. Repairing a Footrail:
1. If footrail is sound, but sagging, it is probably
a. Support footrail at least every 4 feet.
NOTE: Verify histoic appearance first. If
railing is on a significant elevation, it may
not be appropriate to add new support
b. Add properly treated blocking as required.
Consult historic architect for appropriate
blocking type and size.
2. If footrail must be replaced, mill new piece with a
sloped surface to shed water.
NOTE: MAKE SURE THAT A CLEARANCE OF 3" TO NOT MORE THAN 4"
EXISTS BETWEEN FOOTRAIL AND FLOOR.
D. If pieces are completely taken apart, backprime all end
grain surfaces before reinstallation.
E. After all reassembly has been completed and all surfaces
have been sanded ready for repainting, caulk all joints
with a paintable caulk, i.e., where handrail meets
support post, top and bottom of balusters at their
connection with handrail and footrail, and where support
block of footrail meets the floor.
END OF SECTION