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Building a Lighthouse


mgbinspect
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Have you ever wondered how masons built those towering lighthouses and smoke stacks?

Once the location of the structure was established, the masons would work off of a center point. The masons would then measure off of the center point to establish the first course of masonry in a perfect circle.

The masons laid the brick "overhand", meaning they leaned over their work with the finished outer brick facing away from them. The reason for this installation method was practicality. Masons worked from scaffolding within the circumference of the structure, which minimized the amount of scaffolding and number of materials stations needed at any given time during the construction.

As the work went up and the structure radius became progressively smaller, scaffolding became impractical and unnecessary. It was eliminated by using the structure itself for support. Large beams were laid into the masonry which supported stout walk-boards from which the masons continued to lay the masonry "overhand" with their materials staged behind them. Due to the structure being the support system for the workers and the materials, the amount of work that could be installed in a day was limited by the installed material's ability to bear weight. Installed work had to set for a predetermined period of time before it could bear the weight of the scaffolding, workers and materials. Each time the staging was raised, the beams were left in place, but the walk boards were raised with the work.

The dead center of the structure had to be kept clear "line of sight" from the bottom to the top, because all materials were brought up through the center of the structure by rope and pulley. Also, the masons would keep the structure perfectly centered by dropping a plumb bob down through the center of the structure to measure off of their original center-point.

When the structure was complete, the workers would drop the walk-boards to the previous level of beams. They would then remove the beams overhead and close the pocket in which the beams had rested. The beams and walk-boards were let down through the center with the rope and pulley as the materials had been brought up.

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These same techniques are still used today with a couple of exceptions:

They now use a laser instead of a plumb bob and they use elevators for the materials.

My brother, who remained a mason for several years after I moved on worked on an industrial smoke stack in Baltimore Maryland about ten years ago.

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