Exterior door casings that are exposed to the elements often rot at the bottom due to the absorption of rainwater through the wood’s end grain.
To prevent rot when replacing outside door casings, such as brick mold, use casing made from plastic composite material. If wood casing is used:
- Apply wood preservative to the end grain of the casing.
- Allow the wood preservative to dry.
- Prime and paint the end grain of the casing before installing the molding to prevent water absorption.
Steps in Replacing Door Casing
To replace door casing, such as brick mold:
- Use a utility knife to cut through the paint and caulk where the casing meets the door jamb, siding, and miter joint.
- Use a flat pry bar to remove the door casing, being careful not to damage adjoining surfaces.
- Use a putty knife or chisel to remove any old caulking or thick layer of paint on the door jamb or siding.
- Measure from the bottom of the casing to the long edge of the miter joint at the top.
- Cut a 45° miter at the top of the casing.
- Cut the casing to length square at the bottom.
- Position the casing on the door frame.
- Nail the casing to the door jamb and wall stud.
- Caulk any nail holes, joints, and edges.
- Prime and paint the new door casing.
Watch this video to find out more.
- How to Repair Rotten Door Jambs and Brick Mold (video)
- Tips for Cutting Moldings (article)
- Tips for Finishing Trim Molding (video)
- Installing Plastic Molding and Trim on Your Home (video)
- How to Replace Worn Weatherstripping Around Doors (video)
Exterior wood moldings are often the victims of water damage. The proper way to correct this problem is to remove the affected piece and replace it.
Begin by cutting any caulk lines adjacent to the piece with a utility knife, then carefully begin prying it loose with a flat pry bar. If it is attached to other undamaged molding, take care not to split the undamaged piece as you remove the rotten one.
Scrape off any remaining caulking from the surrounding area. Use plastic or composite material for the replacement piece, if you can find it to match the existing molding profile.
Simply measure and cut it to fit where the old piece was located and nail it in place with galvanized finish nails. Then complete the job by filling the nail holes with painter’s putty and caulking around the edges of the new molding.