Calculating A Minimum Radius

The radius is half the diameter of a circle. It is important that you do not try to bend our flexible mouldings tighter than their minimum radius as this may damage the product, and pull it out of shape. You will, therefore, need to know your wall’s radius before ordering. The following formulas show you how to calculate your wall’s radius if you do not know it. If you need any help, please call us.

A Concave Wall

You will need a tape measure and a calculator. This formula assumes that you have a consistent curve.

1. Measure the distance in a straight line between the two end points of your curve, and note the measurement. This is your ‘length’.

2. From the midpoint of this straight line, at 90 degrees measure the distance to the wall, and note it. This is your ‘depth’.

3. Calculate as follows:
Step 1: Divide the depth by 2.
Step 2: Square your length.
Step 3: Multiply the depth by 8.
Step 4: Divide the result from step 2 by the result from step 3.
Step 5: Add the number from step 1 to the number from step 4. This is your radius.

So, for example, if you have a length of 10m and a depth of 4m:
Step 1: 4 ÷ 2 = 2
Step 2: 10 x 10 = 100
Step 3: 4 x 8 = 32
Step 4: 100 ÷ 32 = 3.125
Step 5: 2 + 3.125 = 5.125 Radius = 5.125m

A Convex Wall

You will need a tape measure and a calculator. This formula assumes that you have a consistent curve.

1. Measure the distance in a straight line between the two end points of your curve, and note the measurement. This is your ‘length’. With a convex wall, to do this you will need to extend out at 90 degrees from each end of the curve until you can measure in a straight line between each point with the central point just touching the centre of the curve.

2. Measure the distance back to your wall from both ends (it should be the same at both ends). This is your ‘depth’.

3. Then calculate using the formula from point 3 above.

For An Archway

You will need a tape measure and a calculator. This formula assumes that you have a consistent curve.

1. Measure the distance in a straight line between the two end points of your curve, and note the measurement. This is your ‘length’.

2. From the midpoint of this straight line, at 90 degrees measure the distance to the wall, and note it. This is your ‘depth’.

3. Calculate as follows:
STEP 1: Divide the depth by 2.
STEP 2: Square your length.
STEP 3: Multiply the depth by 8.
STEP 4: Divide the result from step 2 by the result from step 3.
STEP 5: Add the number from step 1 to the number from step 4. This is your radius.

So, for example, if you have a length of 10m and a depth of 4m:
STEP 1: 4 ÷ 2 = 2
STEP 2: 10 x 10 = 100
STEP 3: 4 x 8 = 32
STEP 4: 100 ÷ 32 = 3.125
STEP 5: 2 + 3.125 = 5.125 Radius = 5.125m

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