# How to Determine the Gauge of Your Roofing Nails

To determine the gauge of your roofing nails, it is important to understand how different techniques of measuring and determining any nail work. There is the English ‘penny’ system and then there’s the extensive nail gauge system for roofing nails.

#### The Penny System

In the penny system, nails are labeled as 2d, 3d and so on, going up to 80d. There is debate on how the‘d’ came to represent penny which should have been represented using a ‘p’ concludes that d is used as it represents the first letter of the Roman coin denarius. It is not totally clear how the penny system came into being though with some guessing that the cost of 100 nails of that specific length was then designated a penny rating.

Moving on, the penny system is simple. Against every penny label like 2d, is a length in inches where 2d = 1 inches, 6d = 2 inches, 10d = 3 inches, 20d = 4 inches, 40d = 5 inches, 60d = 6 inches, 70d = 7 inches and 80d = 8 inches. For nails that are used for wood-to-wood works, the measurement used is the penny. For non-wood works nails, the inch measurement is used.

#### Roofing Nails

Roofing nails are non-wood-works nails, are short, diamond pointed with a wide flat head and are measured in inches too. The only addition is that they come with a gauge. The gauge of a roofing nail is not only based on its measured length but also on its head diameter, in inches. To determine the gauge of your roofing nails then becomes a kind of fun project like the ones we had in science labs in school. The point is to measure the length of the nail using a ruler and then the diameter using vernier calipers; the next step is to find the corresponding gauge in the simple chart below.

Length, inches          Gauge              Head diameter, inches

¾                              12                    0.375

11                    0.375

11                    0.438

10                    0.469

9½                   0.484

9                      0.500

8                      0.500

7/8                           12                    0.375

11                    0.375

11                    0.438

11                    0.500

10                    0.469

9½                   0.484

9                      0.500

8                      0.500

1                              12                    0.281

12                    0.375

11                    0.375

11                    0.438

11                    0.500

10                    0.469

9½                   0.484

9                      0.500

8                      0.500

1 1/8                        12                    0.375

11                    0.438

10                    0.469

9½                   0.484

9                      0.500

8                      0.500

1¼                            12                    0.375

11                    0.312

11                    0.375

11                    0.438

11                    0.500

10                    0.469

9½                   0.484

9                      0.500

8                      0.500

1½                           12                    0.375

11                    0.375

11                    0.438

11                    0.500

10                    0.469

9½                   0.484

9                      0.500

8                      0.500

1¾                           12                    0.375

11                    0.375

11                    0.438

11                    0.500

10                    0.469

9½                   0.484

9                      0.500

8                      0.500

It is imperative that you understand the relation between nail lengths and nail gauge using this chart. There are specific gauge nails required for different roofing jobs. Using a gauge or length longer than required can result in the nails sticking out or damaging the roof and using nails with a gauge or length smaller than required can result in the roof collapsing.