Cedar Shingle Exposures (Course Heights)

Mosaic Shingle Company Shingle Exposure And Course Height Guide

The height of cedar shingle exposures can have a huge impact on the way your shingle siding looks and performs. Shingle exposure is the area of a shingle that is visible and uncovered, and it can vary in height dramatically from building to building. The following is a guide to selecting the best shingle exposure for your house:

Typical Cedar Shingle Exposures
The exposure height, sometimes referred to as course height, that is right for your project will depend on a number of factors, including the size of the wall you are covering and the placement of windows and doors. The typical exposure for siding is about 5″ and it should not be less than 4″. The same exposure height is repeated for every course of shingles across the entire building, or as close to it as possible between windows and doors.

Determining Your House’s Existing Exposure Height
If you are re-installing existing siding or just patching your current shingles, you will need to calculate the exact exposure of your existing shingles. Exposure is measured vertically from the bottom of a shingle to the point at which the shingle above overlaps it. On very old siding, shingles may have been installed unevenly or become warped with age, so irregular exposure heights are possible. To get the correct value, measure the exposure of several courses and then calculate the average.

Calculating Exposures on New Siding
To calculate the best course height for new siding, begin by measuring the height of the wall you are working on. Start your measurement from the top of the house foundations and then add an additional 1″ (the amount the lowest shingle should overlap the foundations by). To calculate the number of courses, divide the wall height by your chosen exposure (e.g. 5″) and round your answer to the nearest whole value. To get the exact exposure height, you must then work back by dividing the original wall height by the number of courses.

Adjusting Course Heights
Wherever possible, shingles should align with the top and bottom edge of any windows. To assess whether height adjustments are necessary, start by marking a long wooden pole (such as a furring strip) at 5″ intervals (or whatever your chosen exposure height is). Hold this up against the wall to see whether windows align with the courses. If they do not line up exactly, then exposure should be at least 4″, and if exposures are too short, then course height should be altered and recalculated in order to lengthen them using the same previously stated division technique for determining exposure.

Installing Siding with Accurate Cedar Shingle Exposures
Using the marked wooden pole as a guide throughout the installation process is the best way to achieve straight and even course heights. For additional guidance, you may wish to draw a chalk line or use a furring strip tacked horizontally to mark the bottom edge of where shingles should be.