- Column Plinths
How to install a column using aluminum plinths
Attaching Composition Plaster Capitals
Installing the Column
Split for Reassembly
Fiberglass plinths, aluminum plinths, or lead pads must be used to provide ventilation and act as a barrier against concrete or masonry
Drop a plumb line from the center of the beam to the deck to determine the position of the center point of the plinth so that the column capital will align properly with the beam.
Set two non-corrosive setting pins in the deck on diagonally opposing corners so when installed, they will be flush against the inner wall of the plinth. Allow them to protrude 3o4" from deck to prevent the plinth from shifting. Aluminum plinths are manufactured with pins at each corner. Drill holes in the deck for these pins. Setting pins can be cut 1/4" - 3/8" aluminum, brass etc. rods which can be purchased at a building supply, hardware center or welding shop.
Set the plinth over the pins and check for levelness. Scribe the plinth and use a fine tooth hand saw or hack saw, hack saw or grinder to trim if needed. it is very important that you maintain the same ventilation area originally provided by the plinth.
Reset assembly over dowels and re-check level.
For columns without plinths, follow the same procedure to level the shaft. Reseal the trimmed area with a high-quality oil base paint. Attach lead pads with non-corrosive fasteners before erecting shaft. Maintain space between pads for ventilation.
To prepare the shaft for installation, neatly trim the raw ends from the shaft up to the molding or on the kerf marks. The number 105, 110, 115, 135, 140 and 150 designs all have moldings on both ends of the shaft. The 125 and 130 designs have a molding on the top only, with a kerf mark at the bottom. The number 100 design has a kerf mark on both ends. After trimming paint all raw ends with a high quality oil base paint.
If shaft needs to be trimmed for exact height and is one of our designs that can be trimmed or has been ordered for trimming, measure the distance from the finished beam to the finished floor at the center of where the column will stand to determine the overall height of the column. Measure each column location for variations. Include the height s of the plug when measuring columns with ornamental capitals. The shaft length should be trimmed so the height of the capital (w/plug for ornamental capitals) base and plinth plus the new shaft length will equal the overall height. Always trim from the bottom of the shaft. Measure 4 or 5 places around the circumference of the column shaft to obtain an accurate bottom trim line. Use a length of steel banding or something similar to wrap around and scribe a cutting line. After trimming, coat exposed end grain with two coats of oil base paint for exterior and appropriate sealer for interior columns immediately after cutting.
Apply a high quality caulking to the base where the shaft will rest. Position the base on the shaft and pre-drill for fasteners through the base and into the shaft. Secure the base to the shaft using non-corrosive fasteners.
If attaching wood base with aluminum or fiberglass plinth, pre-drill for non-corrosive fasteners through the plinth into the base, apply caulking where the base will rest on the plinth and attach plinth.
(Illustrations show smaller column assembled in horizontal position, larger column assembled in vertical position.)
When attaching capitals, make sure base squares and capital squares are lined up. Apply caulking to capital where it will rest on the column. Pre-drill for fasteners through capital shaft or up through shaft at a diagonal into capital. Secure with non-corrosive fasteners.
Step 9 - Attaching Composition Plaster Capitals
Attaching composition plaster capitals. Composition plaster caps need a load bearing plug inside so no load rests on the capital. plugs are enclosed with orders that include composition caps with the exception of those split for re-assembly. Columns with a neck diameter of 5" or greater will have a double ring on one end of the plug. This end will insert into the top of the shaft and be secured by nailing before the column is raised into a vertical position. The plug will be 1/8" to 3/8" taller than the capital. Coat all inner and outer surfaces of the capital with a high quality oil base primer and finish paint.
When dry, position the capital over the plug and apply a bead of caulk to the bottom of the cap where it will rest on the shaft. Pre-drill through the capital into the plug and secure with non-corrosive fasteners. Holes in the capital should be countersunk so repairs can be made with patching plaster. Place flashing over capital that is exposed to weather and turn down the edges top form a drip edge. Maintain required opening for ventilation at the top. Please keep in mind unfinished composition capitals cannot get wet before, during or after installation or they will not hold paint and will deteriorate rapidly.
Step 10 - Installing the Column
Place flashing over the capital where it will be exposed to weather and bend the edges down to form a drip edge. Raise the beam so the base, shaft and capital can be placed on the deck. Caulk the beam where it will rest on the flashing and lift the column into position. Lower the beam onto the column and attach it to the capital (or plug ). Use shims to lock the capital in place if the beam cannot be raised. For columns that are assembled in the vertical position, you will position the base as described before sliding shaft into position. Place the cap on top, caulking and flashing same as described above.
Step 11 - Nailing
Use non-corrosive fasteners; either nails or screws. Stainless steel, aluminum alloy or galvanized are acceptable. Do not install wood blocking or any other obstruction to the interior of the column.
Step 12 - Finishing Instructions
Caulk all fastener holes and repair any dents or nicks which occurred during installation with a high quality wood filler. Use patching plaster to repair any nicks or scratches in ornamental composition capitals. Fiberglass components can be repaired with auto body repair kits.
Apply at minimum of two coats of a high quality appropriate paint to all exterior surfaces immediately after installation. See paint manufacturers recommendations for proper paint application.
The Same procedures would apply for interior applications. All surfaces inside, outside and ends should be sealed simultaneously with the same sealer.