Spike's Calculators

# Height Above Plate (HAP) with Heel Cut Depth

You will need to know the height above plate (HAP) measurement to calculate the height of the ridge above the plate. Subtracting the ridge beam's depth from the ridge height will give you the height of the post.

You make the height above plate measurement from the wall's top plate to the top of the rafter along the plumb line.

HAP height depends on rafter depth, the heel cut, and the roof's pitch.

As the pitch of the roof increases, so will HAP. We are looking at it without a birdsmouth cut here;

If your rafter has an exact depth of 12 inches or lays flat (0/12 pitch), the height above the plate is 12 inches. At a 5 /12 pitch, HAP is increased to 13 inches. At a 12 /12 pitch, the height above the plate becomes 17 inches.

Adding a birdsmouth;
```If your heel cut is one inch at a 5/12 pitch, HAP = 12 inches.
If your heel cut is one inch at a 12/12 pitch, HAP = 16 inches.```

## Height Above Plate (HAP)-Heel Calculator

Roof Pitch : 12
Rafter Depth in n
d
Heel Cut in n
d

#### Results:

 Seat Cut in HAP in

#### Calculation

1. the pitch of the roof, amount of rise in inches over a 12-inch run
2. the actual depth of your rafter in inches
3. the length of your heel cut in inches

#### Results

1. the length of the seat cut
2. height above plate (HAP) in inches

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