Rounded Window and Door Bucks

October 24, 2003

by Kris Garrison

"Round Cornered Bucks" 10 minute instructional DVD, VHS or Mpeg Video-- $9.95
NEW! Rounded Window and Door Bucks video ONLINE!

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The Monolithic crew and engineers have improved the augmentation process by developing a simple and easy to assemble rounded corner buck. Rounded bucks, when done properly, produce a "near-wrinkle-free" augmentation.

A typical buck will be 7 1/2" feet tall. A 2x8 or 2x10 or even a 2x12 could be used. Any wood being left in the dome must be pressure treated. Remaining wood, if not pressure treated will rot against the concrete.

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First, measure the vertical part of the curve. Measurement will vary according to engineering per opening.

Cutting the Curve

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Cut out wood sections at the curve. The object in doing this is to get the board to bend. In general, the wood can bend when saw cuts are done on the curve. However, it may be necessary to soak or steam the wood (get and use the greenest boards available). We select heavy wet boards -- usually from the bottom and center of the pile.

Measure for 1/2" inch cuts on the vertical at the curve - cutting vertically into the wood approximately 1 1/4" leaving 3/16" to 1/4".

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Cut on 1/2" spacing first, then widen the top half of the cut by 50% by a second cut. This process allows more wood to be extracted from the inside of the curve making it easier for the wood to bend.

Build a Mandrel

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The mandrel is 1/4th of the circle. The buck is bent around the mandrel to form the 90 degree (1/4 circle) curve. Use 1/2 inch plywood. Mark the curve with a compass. With a saw, cut the round corner. The inside radius for the buck as shown is 4 1/2". The mandrel stays in place until the buck is sprayed in place. It serves as a brace and holds everything in place until glue is set. The mandrel does not require pressure treated wood.

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Spread woodworkers glue into the cutaway. This helps to replace strength from the cut out.

Screw into place a 2x4 on both sides of mandrel to hold straight while bending the buck. Secure to buck and mandrel before bend is made.

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The bottom brace may be removed when building is solid. If it is removed, it does not need to be pressure treated.

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Corner gussets will need to be used as bracing for openings such as Airlock openings.

Putting the Buck Together

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Since each side of the buck is made separately, leave space at the top between each side so that horizontal measurement can be exact. Screw blocks of wood in place to hold the two halves together. Placing a center brace very important.

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Put the top of the buck in place first and then the bottom. Airforms stretch so the buck will fit tight. Then from the outside of the dome, screw 1x2's into place into the fabric to fasten the buck. Attach angle brace or fabric tighteners from the outside of the dome.

Pressure on the Airform may need to be released to allow the buck to be raised up.

Don't forget to buy the instructional video.

Sample Drawings. Click any to enlarge.

Rounded Window and Door Bucks

Cutting the Curve

Build a Mandrel

Putting the Buck Together

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