Exposure is wood trim's worst enemy. Moisture, changing temperatures, UV light and insects attack exterior trim and cut short its useful life. But KOMA Trimboards are another story. New technology has created a polyvinyl chloride (PVC) material that won't swell, rot, split, delaminate, cup or craze under harsh conditions. Yet it's as workable as wood. You can nail, glue, drill, rout and cut KOMA Trimboards using the same tools you would use with wood.