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Architectural Detail Experts | A Blog by Worthington Millwork

How To Install Fiberglass Columns

Posted by Holli McRae on 6/5/13 1:59 PM

Installing fiberglass columns can sometime be confusing or a hassle. We have broken down our installation instructions so that it is easy to install and also fast. This is simple enough that a homeowner can do it! As always if you have any questions on your installation feel free to give us a call!


1. Determine the position of the plinth by dropping a plumb line from the center of the soffit  beam to the floor. Mark this point on the floor with an “X”. This mark is where you will center the plinth so that the top of the shaft will align with the soffit. (Figure 1)Figure 1

2. Measure the overall height. Raise the soffit or porch slightly with brace for easy installation of the column. (Figure 2)Figure 2

3. Trim column shaft on the bottom end only. Trim with an abrasive saw. (Be sure to use personal protective wear.) Finish both the top and bottom of shaft with a rasp or sander to ensure an even load distribution around the entire circumference. (Figure 3)Figure 3

4. Slide cap over top of column shaft. Let cap slide down to rest on the neck mold temporarily until shaft is correctly positioned. (If installing a square column, slide neck mold over top of shaft to desired location. Fasten neck mold to shaft. Caulk between neck mold and shaft.) (Figure 4)

5. Slide base/plinth onto column shaft from bottom. (Figure 5)Figure 4/5

6. Place column in a vertical position with load centered over column shaft with even distribution around bearing surfaces. (Figure 6)Figure 6

7. If installation requires that column be secured in place prior to bearing load, use small L brackets. Be careful to ensure L brackets do not interfere with seating of cap and base/plinth. (Figure 7)Figure 7

8. Remove brace to allow load to bear on column shaft. (Figure 8)Figure 89. POLYURETHANE Cap and Base/Plinth: Slide cap up to soffit and attach to soffit using corrosion resistant screws. Attach to floor using appropriate fasteners. (Figure 9)Figure 9

SYNTHETIC INJECTION MOLDED (SIM) Cap and Base/Plinth: Attach using corrosion resistant screws in the holes pre molded in the cap and base/plinth. Fill holes with exterior caulk or filler.

10. Caulk between cap and soffit, the cap and shaft, and the base and the shaft for a finished appearance.  (Figure 10)Figure 10


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