What you can seal yourself, and what materials cost the least
You can seal most cracks and gaps in your home with materials that cost under $50 total. Caulk, weatherstripping, and spray foam are the three tools that handle the majority of air leaks — around windows, doors, baseboards, and where pipes enter walls. The difference between a $3 tube of caulk and a $12 one is usually brand name, not performance; basic silicone or acrylic latex caulk stops drafts just as well. Weatherstripping (foam tape or rubber strips) costs $5 to $15 per roll and covers 50 to 100 linear feet.
The gaps that matter most are the ones you can feel air moving through. Run your hand around window frames, door frames, and the base of exterior walls on a windy day. That's where to start. Interior gaps — between baseboards and walls, around light switches — matter less for heating and cooling but still reduce drafts. Gaps larger than a quarter-inch wide need caulk or foam; smaller ones can often be left alone.
Key Takeaways
- Silicone caulk and acrylic latex caulk both work for most gaps; the cheapest versions perform as well as expensive brands.
- Weatherstripping foam tape is the fastest and cheapest way to seal around doors and movable windows.
- Spray foam works for large gaps but expands as it dries, so use it sparingly or you'll waste money on excess material.
- Clean out old caulk and debris before applying new material, or the new seal will fail within months.
- The gaps that matter most are around exterior doors and windows; interior gaps are lower priority.
Caulk: when to use it and how to apply it cheaply
Caulk works best for gaps that don't move — around window frames, where walls meet baseboards, and where trim meets siding. Silicone caulk lasts longer (10 to 20 years) than acrylic latex (5 to 10 years), but acrylic latex is cheaper and easier to clean up with water. For a budget project, acrylic latex is the right choice unless the gap is in a wet area like a bathroom or kitchen, where silicone holds up better.
A single tube of caulk costs $2 to $8 and covers about 30 linear feet, depending on gap width. Before you caulk, scrape out old caulk with a putty knife — this is the step most people skip and why their new caulk fails. Wipe the gap clean with a damp cloth and let it dry. Load a caulk gun, cut the tube tip at a 45-degree angle, and run a steady bead along the gap. Smooth it with a wet finger or a caulk tool. You don't need to be perfect; the goal is to fill the gap, not to make it look professional.
Buy a caulk gun if you don't have one ($3 to $8); it pays for itself on the first project. Acrylic latex caulk cleans up with water while it's wet, so have a damp rag nearby. Silicone requires mineral spirits or a silicone caulk remover, which costs more and smells worse.
Weatherstripping: the fastest seal for doors and windows
Weatherstripping is foam or rubber tape that sticks to the frame around a door or window. It compresses when the door or window closes, creating an air seal. A roll costs $5 to $15 and typically covers 50 to 100 linear feet. This is the cheapest way to seal a door or window that opens and closes, because caulk would crack the first time you opened it.
Measure the perimeter of the door or window frame before you buy. Most doors need about 20 feet of weatherstripping (two sides plus top); windows vary. Clean the frame with a dry cloth — weatherstripping won't stick to dust or dirt. Peel the backing and press the tape firmly into place, working from one end to the other. Don't stretch it; let it lay flat. If you apply it crooked, peel it off and try again while the adhesive is still fresh.
Foam tape is the cheapest option ($5 to $8 per roll) and works for most doors and windows. Rubber or silicone strips cost more ($10 to $15) but last longer and compress better. For a budget project, foam tape is fine; you can replace it in a few years if it degrades. Check the thickness — thicker tape (1/2 inch or more) seals better than thin tape, especially if your frame is uneven.
Spray foam: use it sparingly to avoid waste
Spray foam fills large gaps (more than 1 inch wide) that caulk can't handle. A single can costs $4 to $10 and expands as it dries, so a little goes a long way. The problem is that it's easy to use too much and waste money on material you'll have to trim away and throw out.
Spray foam works best around pipes, where they enter walls, and where new construction meets old framing. Shake the can, insert the straw, and spray in short bursts. The foam expands for several hours after application, so stop before the gap looks full. Once it dries (usually 8 to 24 hours, depending on the product), trim the excess with a utility knife. Wear gloves and eye protection; dried foam is hard to remove from skin and eyes.
One can of basic spray foam covers roughly 30 to 50 linear feet of a 1-inch gap, though this varies by brand and how much you let it expand. Read the label before you buy. Avoid the "great stuff" premium brands for a budget project; the basic versions work just as well. Spray foam doesn't work well on moving parts like doors and windows — use weatherstripping instead.
Where to start: prioritize the gaps that matter most
Exterior doors and windows are your first priority because they're where most air leaks happen. Seal the gaps around your front door, back door, and any exterior windows before you move to interior gaps. A single unsealed exterior door can waste as much heat or cooling as several interior gaps combined.
Start with weatherstripping around doors, because it's fast and cheap. Then caulk the gaps between the door frame and the wall. For windows, weatherstripping works if the window opens and closes; caulk works if it's fixed or rarely opened. Check the sills (the horizontal part at the bottom) — water collects there, so use silicone caulk instead of acrylic latex.
Interior gaps — around baseboards, light switches, and interior doors — matter less for heating and cooling but still reduce drafts. Tackle them after you've sealed the exterior. Gaps around pipes and wires where they enter walls are lower priority unless you feel air moving through them.
Tools and materials checklist for a basic project
You probably already own most of what you need. A putty knife (for scraping old caulk), a caulk gun, a utility knife, and a damp cloth are the essentials. If you don't have them, they cost $15 to $25 total at a hardware store or online.
| Material | Cost per unit | Coverage | Best for |
|---|---|---|---|
| Acrylic latex caulk | $2–$5 per tube | ~30 linear feet | Interior gaps, non-wet areas |
| Silicone caulk | $4–$8 per tube | ~30 linear feet | Wet areas, exterior gaps |
| Foam weatherstripping | $5–$8 per roll | 50–100 linear feet | Doors and windows |
| Rubber weatherstripping | $10–$15 per roll | 50–100 linear feet | Doors and windows (longer-lasting) |
| Spray foam | $4–$10 per can | 30–50 linear feet (1-inch gap) | Large gaps around pipes and framing |
| Caulk gun | $3–$8 (one-time) | N/A | Applying caulk |
Common mistakes that waste money or time
The most common mistake is not removing old caulk before applying new caulk. New caulk won't stick to old caulk, so it fails within weeks or months. Spend 10 minutes scraping out the old material; it's worth it. The second mistake is buying expensive caulk or weatherstripping because the packaging looks professional. A $3 tube of basic acrylic latex caulk seals gaps just as well as a $12 tube. Brand name matters less than application.
Using spray foam on doors and windows is another waste. Spray foam expands and hardens, so it will crack and fail when the door or window moves. Weatherstripping is the right tool for moving parts. Applying weatherstripping to a dirty frame is also common — the tape won't stick, and it peels off within days. Clean the frame first, even if it takes an extra five minutes.
Overshooting with spray foam is expensive because you pay for material you throw away. Use short bursts and let the foam expand. If you need more, you can always spray again; if you use too much, you're trimming and wasting. Read the label to understand how much the foam expands before you start.
Frequently Asked Questions
Do I need to remove weatherstripping before I can open a door or window?
No. Weatherstripping compresses when you open the door or window and springs back when you close it. It's designed to move. If the weatherstripping is so thick that the door won't close, you've applied it too thickly or the frame is uneven — peel it off and try a thinner tape or apply it to a different part of the frame.
Can I caulk over old caulk?
Not reliably. New caulk won't bond to old caulk, so it will peel off within weeks. Scrape out the old caulk first with a putty knife. If the old caulk is stubborn, use a caulk removal tool or a heat gun to soften it. It takes 10 to 15 minutes but saves you from redoing the job.
What's the difference between silicone and acrylic latex caulk?
Silicone lasts longer (10 to 20 years) and handles temperature changes better, but costs more and requires mineral spirits to clean up. Acrylic latex is cheaper, cleans up with water, and lasts 5 to 10 years. For interior gaps and budget projects, acrylic latex is fine. Use silicone in bathrooms, kitchens, and around exterior doors where water exposure is high.
How long does caulk take to dry before I can paint over it?
Acrylic latex caulk usually dries to the touch in 30 minutes to an hour, but wait at least 24 hours before painting. Silicone caulk takes longer — check the label, but plan for 24 to 48 hours. Painting too soon traps moisture and causes the caulk to fail. If you're not painting, you can usually use the sealed area after a few hours.
Will sealing gaps reduce my heating or cooling bill?
It depends on how many gaps you seal and how large they are. Sealing all the gaps around exterior doors and windows can reduce heating and cooling costs by 10 to 15 percent, though results vary by climate and how well your home is already insulated. Interior gaps matter less. The payback is usually worth it because the materials are cheap, but don't expect a dramatic change in your bill.