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You can put new siding over clapboards, but it’s not recommended. Some sidings, like vinyl siding, can go over clapboards with sheathing like a foam layer in between. However, it’s best to remove clapboard siding if you plan on replacing it with new siding. Burying wood clapboards underneath new siding can create risks of rot and mold, or hidden insect damage. It can also create warping issues over time. Removing clapboards allows you to properly install a new sheathing, as well as clean up the exterior wall and look for any signs of damage.

The clapboard exposure, also called the reveal, refers to the amount of clapboard visible in the siding. Clapboards always overlap slightly, but some overlap more than others. The exposure is the vertical measurement of the board that remains visible as the clapboard is installed.

When repairing clapboard siding, it’s important that you match the exposure of your current clapboards. You may want to take a measurement of the specific exposure on your siding for reference in repairs.

The recommended PSI (pounds per square inch) for cleaning vinyl siding can vary, so it's best to consult the manufacturer's guidelines. Generally, vinyl siding can handle high pressure, from 2,500 to 3,500 PSI. For comparison, more delicate materials like wood and aluminum siding should not face more than 1,500 PSI. To safely disperse the pressure on vinyl, use a tip with a wider spray span, such as a green (25-degree) or yellow (15-degree) nozzle. For routine cleaning of light dirt, a garden hose with a spray nozzle may be sufficient. Always exercise caution to avoid using excessive pressure that could damage the siding.

Avoid toxic chemicals that can leach into nearby lawns, as well as household ingredients like vinegar that can ruin paint and sealants. Instead, look for a very light detergent or a dedicated exterior siding cleaner. In a pinch, you can use a basic dish or laundry soap, but we suggest sticking with a dedicated cleaner.

If your siding is struggling with algae or moss, which indicates moisture issues, look for an outdoor cleaner that’s specifically designed to clear moss and algae stains. This is also a sign that you need to seal your clapboard against further problems.