Start with the space you can actually use.

1. Define the treatment rectangle

Enter the actual width and height of the area the decorative treatment will occupy. This may be smaller than the entire wall. Decide whether existing baseboards, crown molding, or another feature sits outside that rectangle before taking measurements.

Measure width at the top, middle, and bottom, and height at several points. Walls and existing trim may not be square. Use dimensions that fit the intended treatment area, and check the drawing against the real wall before committing to a layout.

All margins and spacing are measured within this rectangle. A frame margin does not automatically account for a baseboard or other trim outside it.

2. Use actual sizes and consistent units

Use the measured face width of the trim, not a nominal lumber size. Keep every measurement in the selected unit: inches or centimeters. One inch is exactly 2.54 centimeters.

To enter a fraction as a decimal, divide its numerator by its denominator: ¼ inch is 0.25, ½ inch is 0.5, and ¾ inch is 0.75. A measurement of 3½ inches is 3.5 inches.

Displayed measurements may be rounded for readability. Check the precision you need for your material, joints, and tools rather than treating the screen's rounded labels as cutting marks.

3. Locate one keep-clear area from the top left

The planner checks one rectangular keep-clear area at a time. Measure its left edge from the treatment rectangle's left edge and its top edge down from the rectangle's top edge. These are its X and Y coordinates. Then enter its width and height, including any casing, cover plate, or clearance you want to preserve. The full rectangle must fit inside the treatment area.

For example, X = 24 and Y = 18 places the obstacle's top-left corner 24 units to the right and 18 units down. It does not place the obstacle's center at that point.

An overlap highlight is a geometry check. It does not move the layout, shorten the cut list, assess installation requirements, or tell you whether a location is safe to work on. If there are multiple obstacles, check them individually and verify the complete layout on the real wall.

Picture frames: outside size versus inside opening

A frame's outside width and height describe its external edges. With 45-degree mitered corners, the horizontal pieces use the outside width measured between their long points, and the vertical pieces use the outside height measured between their long points.

The clear inside opening is smaller. For a frame 36 inches wide with trim 2 inches wide on each side, the inside width is 36 − 2 − 2 = 32 inches. Do not use that inside width as the outside long-point cut length.

These relationships assume consistent trim width, square rectangular frames, and 45-degree miters. Stock purchasing also needs to account for saw kerf, end trimming, defects, and your chosen cutting sequence.

Battens and wainscoting: decorative layout geometry

The batten layout represents decorative rails and vertical stiles applied over an existing surface. It is not a design for exterior board-and-batten siding, a wall assembly, or structural framing.

Rails run horizontally; stiles run vertically. In the board-and-batten layout, the top and bottom rails span the full treatment width, and the vertical battens fit between them. Their length is the treatment height minus the two rail widths.

In the wainscoting layout, the vertical stiles run the full treatment height, and horizontal rails fit between them at each panel boundary. These two layouts use different joint arrangements; use the cut list for the treatment you selected.

A wainscot treatment rectangle covers only the decorative area you choose. The planner distributes the rails, stiles, or frames inside that area. It does not determine required wall height, assess the underlying surface, or provide building-code or electrical guidance.

Check the plan at full size

Mark the proposed outlines on the wall with a suitable removable method. Compare margins, openings, corners, and obstacles with the drawing. Check each final length against the actual installation location before cutting.

The diagram is a planning reference, not a full-scale cutting template. Measure the wall directly rather than taking measurements from a printed or resized image.