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Project Difficulty:
Easy
Estimated
Project Time: Varies according to size of job
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| Tools and Materials: |
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Putty knife or chisel
Wire brush
Foam or fiberglass filler, as needed
Utility knife
20d nail
Caulking compound cartridges, as needed
Caulking gun
Wooden craft stick or ice cream stick
Water or other recommended solvent
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Of all the home maintenance chores to tackle, caulking air leaks around such places as windows, doors, and pipes is one of the most economical, effective, and easy to do. By sealing these gaps you will be cutting down the flow of air, moisture, and dirt (and insects) that can pass unchecked through these gaps. You'll also be saving yourself money on heating and air conditioning bills.
The easiest way to detect the source of an air leak inside the home is to wait for a cold, windy day and then hold a tissue up to a suspect area and see if the tissue flutters. Smoke from a stick of incense can also work. On the outside of the house, look for obvious cracks around windows and doors, gaps between the siding and foundations, and holes where wires and conduit enter the home. If there is old caulk, decide whether or not it should be replaced. To test the soundness of a caulked joint, press the blade of a putty knife into the caulk. If the caulk is still "gummy," you don't need to replace it. If, however, the caulk cracks and falls out of the joint when you scratch it with the putty knife, you need to remove the old and apply new caulk.
Selecting a Caulk
There are many different types of caulk available today and one of the hardest parts of caulking a gap is picking the most suitable one to use for the job. The best source of information to guide you is the package label. In general, however, the more expensive caulks will perform better, last longer, and in the long run, will save you money and reduce the number of times you will need to redo the job. If sealing gaps on the outside of the house, choose an exterior caulk; if working inside the home, use an interior-grade caulk. It's also important to match the caulk with the type of surfaces being sealed. There are special products for use specifically on masonry or roofing surfaces, but when caulking around windows and doors, select a caulk that will adhere to various types of surfaces. In addition, consider the materials in the caulk, its ease of use, how long it takes to dry and cure, and whether or not it can be painted to match the areas being sealed, and how long it will last. The following general information on some common caulks should help. Be aware, though, that the life span of a caulk will depend on the actual conditions it is subjected to over the years and that there is simply no guarantee that your circumstances will be the same as those tested by the manufacturer.
* Acrylic latex caulk is slightly longer lasting than similar, less expensive vinyl latex. It is easy to apply, but degrades in direct sunlight and adheres poorly to porous surfaces. It dries in about 30 minutes and takes about 1 week to cure, but it will last for 5 to 10 years.
* Butyl, also called butyl rubber, has better adhesion and stretching ability than acrylic, but costs more and takes longer to cure (about 6 months). It's good for sealing masonry joints, and after about 24 hours its outer layer has formed a skin. Although it degrades in sunlight, it can last 5, 10, or even up to 20 years.
* Polyurethane caulks are expensive and more difficult to apply than latex and butyl, but they last longer, can cover a wider gap (up to 3/4 inch), and will stretch farther. It takes about 2 days for the outside to skin over, about 1 month to cure fully, and it can last more than 20 years.
* Silicone caulk--not to be confused with paintable siliconized acrylic--has good stretching ability and can cover a 1-inch gap, but it can't be painted and it adheres poorly to plastic and wood. Its outer skin forms in about 1 hour and it takes about 1 week to cure. Silicone caulk can last over 20 years.
* Oil-based caulk is inexpensive and you can use it almost anywhere. But oil-based caulk tends to "dry out" in cracks and when dry, it falls out, or it shrinks in the cracks when the oil in the caulking disappears. It can be painted, but if you use this product, plan on recaulking within 3 years.
Applying Caulk
Although the illustrations used here are for sealing a gap around a window, the general techniques apply for sealing cracks at other locations. Refer to these instructions while also following the manufacturer's guidelines on the caulking cartridge.
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1.
Prepare the Area
Using a putty knife or chisel, remove all the old caulk and clean the area of any loose dirt, dust, paint, and debris (Fig. 1). Then use a wire brush to clean the area and rough up the surface so that the caulk will stick better.
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2.
Fill Deep Cracks
If the crack is deep, pack it using filler such as foam rope or fiberglass insulation, pushing it deeply into the void (Fig. 2). Don't use newspaper as filler; if it becomes wet, it will rot. Avoid steel wool, too, because if that gets wet, it will rust and the water running from it can streak the paint or finish on the house. Most home centers sell small, inexpensive bags of material to use as filler.
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3.
Prepare the Cartridge
Using a utility knife, cut the tip of the cartridge at about a 45-degree angle, making a tapered point--small at the tip and larger at the base (Fig. 3). The farther down the tip of the cartridge that you cut, the wider the opening will be. Try to cut a point that will produce a bead of caulk to match the size of the joint to be filled. If you're caulking several joints, figure an average for the crack widths and cut the nozzle accordingly. Some caulking manufacturers stamp a graduated scale on the plastic nozzle to help you cut it properly. For example, if you want to fill cracks that average 1/4-inch-wide, cut the nozzle at the "1/4" marking. Look very closely; the markings can be hard to see.
Once the nozzle is cut, puncture the seal within the cartridge by feeding a 20d nail down into the nozzle. You need to break this seal so that the caulk will come out.
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4.
Load the Cartridge into the Gun
Pull back the plunger of the cartridge gun and insert the cartridge into the gun. To operate the caulking gun, turn the plunger in back of the cartridge to engage the trigger mechanism, and then squeeze the trigger to release the caulk.
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5.
Apply the Caulk
Hold the caulking gun at about a 45-degree angle to the joint being filled, and then pull the gun toward you, sliding the tip along the crack you're filling and pressing the trigger at the same time to release a steady flow of caulk (Fig. 4). The bead of caulk should fill the gap and be wide enough to span both surfaces. When you're nearing the end of the run, release the pressure on the trigger. As you work, you'll get the hang of the speed at which you need to move the caulking gun in relation to the amount of caulk coming out of the nozzle. If you pull the gun too slowly down the crack, too much caulk will enter the joint. If you move too quickly, the bead of caulk will be too thin to completely fill the joint.
When you're at a stopping point in the job, turn the plunger at the back of the caulking gun. This releases the pressure so that the caulk won't ooze out of the nozzle and make a mess.
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6.
Smooth the Surface
If the surface of the caulk comes out rough and uneven, it's a simple step to smooth things out. You can use your finger or, if you prefer, a rounded, wooden craft stick (or the stick from an ice cream bar). Moisten either of these tools--your finger or the stick--with water; then lightly run it along the surface of the caulk. The goal here is to create a concave joint--something that will fill the crack, look attractive, but not be so concave as to trap excessive moisture, which would hasten the decay of the caulk (Fig. 5). Use a cloth to wipe the excess caulk off your finger and rewet your finger or stick, as needed. Use plenty of water and work slowly. Clean up any mess or drips using the solvent recommended by the manufacturer of the caulk.
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7.
Store the Leftover Caulk
If there is any caulk left in the cartridge after you have finished the project (you'll know by how far the plunger has gone down into the cartridge), plug the tip of the nozzle using a 20d nail or golf tee to keep the caulk fresh for the next project. (Fig. 6)
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8.
Allow the Caulk to Dry and Cure
If the caulk is paintable, give it enough time to dry enough to form a seal or light "skin" on the surface. This is usually noted on the package directions. When the caulk is fully cured, it means that it has become stable and will no longer shrink.
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