How to Check and Repair Caulking

Caulk isn’t glamorous, but it’s working every day to keep water out of your walls and air inside your home. When it fails, water finds a way in. And water always wins eventually. A little maintenance goes a long way.

Why This Matters

Caulk seals the gaps where different materials meet—where your tub meets the tile, where windows meet siding, where countertops meet walls. When it fails:

• Water seeps in – Behind tile, under tubs, into walls
• Rot starts – Wood stays wet and decomposes
• Mold grows – In dark, damp spaces
• Drafts increase – Heated and cooled air escapes
• Energy bills climb – Your HVAC works harder
• Pests enter – Tiny gaps are doorways for insects

A $5 tube of caulk can prevent thousands in water damage.

Where to Check

Walk through your home and inspect these areas:

Bathrooms

• Around bathtubs and shower bases
• Where tile meets tub or shower pan
• Around sink countertops and backsplashes
• Where toilet meets floor (some use caulk, some don’t)

Kitchen

• Around sink countertops
• Where backsplash meets counter
• Around window frames above sink

Windows and Doors

• Interior trim where it meets drywall
• Exterior where frame meets siding
• Bottom of exterior door frames

Other Areas

• Where siding meets corners or trim
• Around outdoor faucets and vents
• Where dryer vent exits the house
• Any gap between different materials

Signs It’s Time to Replace

Look for:

• Cracks or splits – Caulk has lost flexibility
• Gaps pulling away – From either surface
• Discoloration – Yellowing or darkening
• Mold or mildew – Black spots that won’t clean off
• Soft or mushy texture – Water has gotten behind it
• Missing sections – Pieces have fallen out

If you can see the problem, water can find it.

Choose the Right Caulk

Not all caulk is the same. Using the wrong type means doing it again sooner.

Area	Best Caulk Type
Bathtub/Shower	100% silicone (waterproof, flexible)
Kitchen/Countertops	Silicone or silicone-acrylic hybrid
Windows/Doors (interior)	Paintable acrylic latex
Windows/Doors (exterior)	Elastomeric or silicone-acrylic
Siding gaps	Polyurethane or elastomeric
Gaps > ¼ inch	Fill with backer rod first, then caulk

Read the label. Some caulks say “siliconized” but aren’t 100% silicone. For wet areas, get the real thing.

Step-by-Step Repair

1. Remove the Old Caulk

Don’t caulk over old caulk. It won’t bond properly.

• Use a utility knife or caulk removal tool to cut along both edges
• Peel or scrape out the old material
• For stubborn silicone, there are adhesive removers that help
• Clean the area thoroughly with rubbing alcohol or mineral spirits
• Let it dry completely—caulk won’t stick to wet surfaces

2. Prep the Gap

• Remove any loose debris
• For gaps wider than ¼ inch, push in foam backer rod first
• This gives the caulk something to sit on and uses less product

3. Apply Masking Tape (Optional)

For a neater line, apply painter’s tape on both sides of the gap, leaving just the gap exposed. Remove while caulk is still wet.

4. Apply New Caulk

• Cut the tip at a 45° angle, hole size matching the gap
• Puncture the inner seal if there is one
• Apply steady pressure on the trigger
• Move at a consistent speed
• Fill the gap completely in one pass if possible

5. Smooth the Bead

• Wet your finger (use water for latex, rubbing alcohol for silicone)
• Run your finger along the bead to press it into the gap
• Wipe excess on a damp rag
• Work quickly—some caulks skin over fast

6. Let It Cure

• Acrylic latex: 24 hours before painting
• Silicone: 24-48 hours before water exposure
• Check the tube for specific cure times

Warning Signs of Hidden Damage

If you remove old caulk and find:

• Soft or crumbly drywall behind it
• Dark staining (mold)
• Soft wood or visible rot
• Gaps into wall cavities

You’ve got more than a caulk problem. Water has been getting in for a while.

DIY vs. Call a Pro

DIY: Tub surrounds, sinks, windows, doors, visible gaps. Straightforward with a little practice.

Call a pro: Extensive water damage, rotted wood, large exterior projects, areas requiring scaffolding or ladders, or if you just want it done right the first time. Find a handyman →

How Often to Check

• Quick visual: Every 6 months
• Full inspection: Once a year
• Bathrooms: More often due to moisture exposure

The Bottom Line

Caulk fails slowly, then all at once. Check it once a year, replace what looks tired, and use the right product for the job. It’s the cheapest insurance against water damage you’ll ever buy.