(Or: You mean they’re not all the same?)
Choosing the right caulking to seal the bathtub or fill a gap in your crown molding can get confusing. Especially when the caulking descriptions can be both specific and vague. Here’s how to figure out which caulk goes with which room inside and outside your house – what’s paintable, what’s waterproof, and which one to avoid.
Especially if it was built a few decades ago. A newer single-story house on a concrete slab may have its disadvantages, but your multi-story, wood-frame, crawlspace or basement house is gonna move – a lot.
New floors settle. Old framing shifts. Seasons expand and shrink everything twice a year. And suddenly you’ve got seams opening up where there weren’t seams before.
That’s not failure.
That’s physics.
The fix is usually simple:
Caulk.
But choosing the wrong caulk can leave you with cracks, peeling, mold, or a mess that never really cures.
Let’s pick the right one the first time.
First: Not All Caulk Is the Same
If you walk down the aisle and grab the first tube that says “All Purpose,” you’re gambling.
Caulk is designed for very specific jobs.
Here are the main types you’ll actually use:
1. Acrylic Latex Caulk (Painter’s Caulk)
Best for:
- Baseboards
- Trim
- Interior seams
- Small gaps before painting
This is your everyday, indoor caulk.
It:
- Cleans up with water
- Is paintable
- Is easy to apply
- Is forgiving
If you’re sealing trim to a wall where new floors have opened a seam — this is usually the right choice.
Look for “paintable” on the tube.
2. Siliconized Acrylic Caulk
This is acrylic caulk with a little silicone blended in.
Best for:
- Areas that need a little more flexibility
- Kitchens
- Light moisture areas
It stretches better than plain acrylic and resists cracking longer.
For older homes that move seasonally?
This is often the sweet spot.
3. 100% Silicone Caulk
Best for:
- Showers
- Sinks
- Exterior windows
- High-moisture areas
Silicone is:
- Extremely flexible
- Waterproof
- Long-lasting
But…
- It is not paintable
- It’s harder to work with
- It’s messy if you’re inexperienced
If you’re sealing a bathroom or exterior joint, use silicone.
If you’re sealing baseboards and plan to paint, do not use 100% silicone.
4. Polyurethane Caulk
Best for:
- Exterior gaps
- Concrete
- High-movement joints
It sticks like crazy.
It’s durable.
It’s harder to tool.
Overkill for interior trim. Perfect for exterior cracks.
What Should You Use for Floor Seams and Trim?
In an older house with settling floors?
Use:
High-quality paintable acrylic latex or siliconized acrylic caulk.
You want:
- Flexibility
- Paintability
- Easy application
- Easy cleanup
You do not want:
- Pure silicone (won’t take paint)
- Construction adhesive (wrong product entirely)
How Big of a Gap Is Too Big?
Caulk is not gap filler.
If the gap is:
- Less than 1/4″ → Caulk is fine.
- Larger than 1/4″ → Consider backer rod first.
Backer rod is foam you press into the gap so you’re not filling a canyon with $6 worth of caulk.
Should You Use Your Finger?
Short answer: Yes.
Long answer: Yes, but clean.
After running a bead:
- Lightly wet your finger.
- Smooth the bead with steady pressure.
- Wipe excess on a rag immediately.
There are fancy tools, but a steady finger works just fine.
Pro tip:
Don’t overwork it. One smooth pass.
Common Caulking Mistakes
- ❌ Cutting too large a hole in the nozzle
- ❌ Skipping painter’s tape when you should have used it
- ❌ Using silicone where you need paint
- ❌ Filling large structural gaps
- ❌ Applying on dusty surfaces
Caulk sticks to clean, dry surfaces. Always wipe the seam first.
How Long Does Caulk Last?
Interior acrylic caulk:
5–10 years, depending on movement.
Silicone:
10–20 years in wet areas.
If it cracks, separates, or shrinks noticeably — replace it.
Product Recommendations
A basic homeowner setup:
- 3 tubes of quality paintable acrylic caulk
- 1 tube of kitchen/bath silicone
- Dripless caulk gun
- Backer rod (for wider gaps)
- Disposable gloves
- Small rag
That’s a $40 investment that saves you repainting trim later.
The Bottom Line
Your house moves.
Caulk is how you make peace with that movement.
Choose:
- Acrylic for paintable interior trim
- Siliconized acrylic for paintable flexibility
- Silicone for wet areas
- Polyurethane for exterior toughness
Don’t overthink it.
Just match the product to the problem.
And remember:
If the seam showed up once, it may show up again.
That’s normal.
SEO Title Variations
- What Type of Caulk Should I Use?
- Best Caulk for Trim, Floors, and Bathrooms
- Acrylic vs Silicone Caulk: What’s the Difference?
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