Weatherizing 5 - Caulking to Reduce Energy Loss Weatherizing 5 - Caulking to Reduce Energy Loss

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Caulk is a material that forms a flexible seal to stop air and moisture infiltration. Some of the better types of caulk will last up to 20 years. Although these are more expensive, they will save you the time and expense of recaulking frequently.


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Caulk is used on window and door frames, siding, corner joints, foundations, and almost any area in which you find a seam or crack.

Take another look at the weatherization audit section. Most of the items checked off in the "not so obvious" category are prime targets for caulking.

There are many types of caulk for various uses, so check with your home center to find out what type will work best for your particular needs. Generally, you will apply caulk from a tube with a caulking gun or from a pressurized can. A standard cartridge of caulk will give you approximately 25 feet of 1/4" bead. You can also purchase rope caulk which comes in a coil and is simply unwound and stuffed into cracks and crevices.

The trick to a good caulking job is learning to draw a good, even bead. This may take a little practice but it will work easier if you hold it at a consistent angle and draw the bead continuously rather than in a stop-and-start fashion. A trick here is to release the trigger before pulling the gun away to avoid excess caulk oozing out. Cut the nozzle with a sharp razor blade or utility knife to about a 45-degree angle. Then pierce the seal on the cartridge to allow the caulk to flow evenly.

Since caulking is a major element of weatherization, access to an air compressor would come in very handy. Fitted with a caulking gun attachment the air compressor allows a smoother, almost effortless application in all areas needing caulk.

Be sure the seam or crack you are filling is free from any built-up paint or old, deteriorated caulking. Use a putty knife or a large screwdriver to scrape the opening clean. There should be no moisture in the crack before applying the caulking, or it will be trapped inside once the caulk sets up.

If you are trying to cover both sides of a crack of seam with a single wide bead of caulk, make sure it adheres to both sides. The bead of caulk needs to be on the inside of the crack, so if the bead that you draw is on the surface of the material, use a putty knife to force it into the crack or seam and smooth it out. A little practice will give you the proper angle at which to hold the can or gun so that the caulk will be forced immediately into the crack as it comes out of the tube.

There are no practical alternatives to caulking. If you weatherstrip and caulk in addition to insulating your home, you will reduce your energy bill considerably.

The joint between the door frame and the exterior and interior walls can be as much as an eighth of an inch gap. This must be carefully and completely caulked to seal it against energy loss.

In many of the older homes, there is a space between the windows that contains the weights for the older double-hung windows. This area is usually not insulated and can leak. Just like the doors, there is that fractional gap between the frame and the walls of the house. Caulking the outside of the window frame where it joins the overall structure of the house will halt this flow of air.

Note: Never caulk the little openings in storm windows. They have a very specific purpose; that is, allowing moisture to escape and not condense on the glass.

Cracks in the foundation or basement walls can be terrific energy losers. You'll want to be certain the crack is very clean. Remove any loose mortar, dim and moisture. You may even want to go over it with a primer if the material is porous.

Smaller cracks can be sealed off with just a liberal bead of caulk forced smoothly into the crack. Extra deep cracks should be stuffed with polyethylene foam, fiberglass, or oakum to within 1/2" of the top surface. Then caulk over this to provide a seal.

If dissimilar materials meet - at sidewall and foundation, sidewalls and roof, chimney and house, or a porch and the house - a seal of caulk will reward you with lower energy bills.

Where utility pipes, vent pipes, exterior plumbing, and electrical or phone connections enter the house, caulk the separation. If any of these penetrate the ceiling below an unheated attic or the wall to a garage, caulk them as well.

On roofs or siding, repair areas around flashing with caulk or a sealant recommended for exterior metal. Seal flashing around roof stacks and vents, between roof valley flashing and shingles, and around roof additions and skylights. There are also types of adhesive caulking that will mend split or loose roofing shingles as well as splits or cracks in siding. (These are available in a variety of colors.) Exposed roofing nails should also get an application.

Keep all gutters, downspouts, soffits, and eaves clean and in good repair.

Caulk them to prevent rot decay, basement flooding, mildew, and dampness problems.

Tip: If you are not using your fireplace, plug up the flue with insulating fireplace baffle (damper) to prevent warm air from doffing up and out of your home.



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