Install Baseboards and Trim
Add the finishing touches with baseboards and door casings that hide gaps, protect walls, and give your basement a polished, professional appearance.
Why Trim Work Matters
Trim work is the difference between a DIY-looking basement and a professionally finished space. Baseboards cover the gap between walls and flooring where expansion and imperfect cuts are inevitable. Door casings frame openings and hide rough framing. Crown molding adds elegance and can make low ceilings appear taller. Quality trim installation requires precision measuring, accurate cutting, and attention to detail, but transforms your basement into a true living space.
Tools & Materials Needed
Step-by-Step Guide
Measure and Cut Baseboards
Accurate measurements and cuts are critical for professional-looking trim:
- •Start in the least visible corner and work toward the main entrance
- •Measure each wall individually - don't assume opposite walls are the same length
- •For outside corners: Cut both pieces at 45-degree angles to create miter joint
- •For inside corners: Install first piece square, cope the second piece to fit
- •Cut pieces 1/16 inch long - they'll spring into place for tight fit
Pro Tip: Write the wall location and orientation on the back of each piece with pencil to avoid mixing them up.
Install Baseboards
Attach baseboards securely to wall studs:
- •Locate studs with stud finder and mark with light pencil above baseboard height
- •Apply small bead of construction adhesive to back of baseboard (optional but recommended)
- •Position baseboard and nail into studs with 2-inch brad nails every 16 inches
- •Nail along bottom edge into flooring with 1.5-inch nails every 12 inches
- •Angle nails slightly for better holding power
Install Door Casings
Frame door openings with mitered casing:
- Mark a 3/16-inch reveal line around door jamb with combination square
- Cut side casings square at bottom, 45-degree miter at top
- Install side casings first, aligning with reveal line
- Measure between side casings at top, cut head casing with 45-degree miters
- Test fit head casing - miters should close tightly
- Nail casings into jamb and wall studs with 1.5-inch and 2-inch brads
Watch Out: Walls are rarely perfectly square. Test fit all pieces before nailing. Slight adjustments to miter angles are often needed.
Fill Nail Holes and Gaps
Create seamless finish by filling imperfections:
- •Use wood filler for nail holes - press in with finger, overfill slightly
- •Use paintable caulk for gaps between trim and wall/ceiling/floor
- •Run smooth bead of caulk, tool with wet finger for clean line
- •Fill any gaps in miter joints with wood filler or caulk
- •Let filler and caulk dry completely (2-4 hours minimum)
Sand and Paint/Stain
Complete the installation with finishing touches:
- •Lightly sand all filled areas with 150-grit sandpaper until smooth
- •Wipe down with tack cloth to remove dust
- •For raw trim: Prime with high-quality primer, then apply two coats of paint
- •For prefinished trim: Touch up filled areas with matching paint pen or small brush
- •Use semi-gloss or satin finish for trim - easier to clean than flat
Pro Tips
- ✓Buy 10% extra trim to account for mistakes and future repairs
- ✓Let trim acclimate to basement humidity for 24-48 hours before installation
- ✓Caulk AFTER painting for cleanest results and easiest touch-ups
- ✓Keep a piece of scrap baseboard for future patching and repairs
- ✓Use a fine-tooth blade in your miter saw for cleanest cuts on prefinished trim
Frequently Asked Questions
Should I use prefinished or raw trim?▼
Prefinished trim saves significant time and eliminates painting on-site, with factory finish being more durable. However, it costs 20-40% more and touch-ups are harder to match. Raw trim is cheaper and easier to repair but requires priming, painting, and drying time. For DIYers, prefinished is often worth the premium to avoid painting hassles.
What size baseboard should I use in a basement?▼
Standard baseboard heights are 3-5 inches for modern style and 5-7 inches for traditional. In basements with lower ceilings (7 feet), use shorter baseboards (3-4 inches) to avoid making the space feel cramped. With 8+ foot ceilings, taller baseboards (5-7 inches) add visual weight and elegance. Match existing trim in adjacent rooms if possible.
How do I cope inside corners on baseboards?▼
Coping creates tighter inside corners than miters. First, install one baseboard square into the corner. On the adjoining piece, cut a 45-degree inside miter, then use a coping saw to cut along the profile revealed by the miter, cutting at 90 degrees to the back. This creates a piece that fits perfectly against the first board's profile, even if walls aren't perfectly square.
Can I install trim without a nail gun?▼
Yes, but it's much slower and more difficult. You can hand-nail trim with finishing nails and a hammer, but you risk splitting the wood and denting the trim with hammer marks. A manual brad nailer works but requires significant hand strength. An electric or pneumatic brad nailer ($50-150) makes the job faster, easier, and more professional-looking. Consider renting if you don't want to buy.