20 X 40 X 4 Square J Channel Louvered Custom Vent

https://onyxxteriors.com/info/explore/20-X-40-X-4-Square-J-Channel-Louvered-Custom-Exhaust-Vent.php

Working with a common 4 inch deep vent gives a choice of where the flange will be located.

This J channel was not set on the face or the back.

There is a full 3 1/2" of vent wall to work with.

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Square louvered custom exhaust vents

At 20 x 40 inches on the vent face, the louvers are set at 2 inches apart.

This gives almost no air restriction.

The face of the vent is trimmed neatly with an inch border.

Then the J channel is added and recessed adding another inch of trim.

The J channel trim face will cover the siding edges.