How to Repair Vinyl Siding

by on August 26, 2012Karie Fay

Vinyl siding is kind of like an old, faithful car or your favorite pair of well-worn slippers: Chances are, it’s nothing fancy and it probably blends into the background, lacking the flash and dazzle of other, more unusual choices. It’s comfortable, however. Water won’t rot vinyl siding, and bugs can’t destroy it. It won’t peel and need repainting. There’s no warping, twisting, cracking and chipping caused by seasonal weather changes. And it lasts – often for 50 years or more. Coupled with many color options and an affordable price tag, it’s little wonder that vinyl siding is one of the most popular siding choice in America today. In fact, according to This Old House magazine, more than a third of new and existing homes feature vinyl siding.

how to repair vinyl sidingSo what’s the drawback? Vinyl siding may warp when subjected to intense heat, such as from a grill placed too close. Even more commonly, flying debris from lawn mowers, baseballs hitting the house or hail pelting the exterior will leave marks. Repairing dents is a matter of choice as it typically causes merely cosmetic damage. Cracks, holes and damage that leaves gaps in the siding offers you only one choice: You must repair it.

Underneath any properly installed vinyl siding is a layer of plastic sheeting or another form of house wrap. (In fact, if you find exposed plywood wall sheathing during siding repair, stop and brace yourself for a complete siding removal and replacement.) House wrap creates a moisture barrier that keeps wind-driven rain and other sources of moisture from invading your walls and, ultimately, rotting your home. But house wrap is thin and vulnerable to insects, the elements and other damage. Your vinyl siding thus not only makes your house look finished, but serves as the initial barrier or skin of your home.

Vinyl siding interlocks at top and bottom. The installation starts at the bottom of the wall and finishes at the top. For damage resulting in a small hole, you don’t have to worry about removing any siding. However, some damage requires replacement of the damaged piece. Use a zip tool to “unhook” the damaged piece before installing a new one.

Repairing Small Punctures and Holes

1. Clean the siding surrounding a small puncture or hole. Wipe over the damaged area with a wet, soft cloth or sponge to remove surface dirt and debris that will interfere with patch bonding. If the siding is fairly dirty, however, the clean area will stick out like an eyesore. Scrub the entire wall instead. Fill a 5-gallon bucket with warm water. Add two-thirds cup TSP (trisodium phosphate) and about one-half cup powdered laundry detergent per gallon of water for a general purpose cleanser. Mix a solution of two-thirds water and one-third white vinegar or one-quarter bleach and three-quarters water to clean and treat stains or mold, alternatively. Spray the grass and any greenery below the wall until thoroughly drenched to prevent the grass from absorbing chemicals. Covering them with plastic sheeting also helps.

Spray the wall with a wide, gentle flow of water from a garden hose – the force behind a pressure washer can easily get behind vinyl siding, especially in damaged areas – always aim the stream directly at the siding as much as possible, rather than at an angle. Spray from the top of the wall down. Scrub the wall gently with the cleansing solution, working from the bottom to the top. Use a long-handled car brush or similar tool to reach high areas. Rinse again, from the top down, and allow the siding to dry completely.

2. Load a caulk gun with color-matched caulk or sealant. Trim the tip to an angle, using a utility knife, and insert the tube into a caulk gun. Squeeze the trigger until the caulk emerges. Wipe away the first squirt. Clear silicone caulk will also work, but colored products blend in better. Look for color-matched caulks, designed to blend with many shades of vinyl siding, at siding wholesalers or specialty stores. Home improvement centers may also have a selection. If possible, take a sample of your siding with you to obtain the best match, or record the manufacturer and color name and inquire about specialty matches.

3. Fill the hole with caulk. Hold the gun so the tip is against the hole and squirt the caulk into the hole like you’re filling a doughnut with jelly. As the caulk fills the space between the siding and sheathing, draw the gun away to leave a slight mound over the surface. Avoid spreading or smearing the caulk over the surrounding siding. The messier the caulk job, the more obvious the repair will appear.

4. Trim away excess caulk. Cure the caulk – allow the chemicals to react and the formula to dry completely – for several days, or as specified on the product. Use a utility knife to carefully shave across the top of the repair, leaving it flush with the surrounding siding. The hole is now waterproof and weather resistant.

Installing a Vinyl Patch

1. Cut a vinyl siding patch. Measure the width of the damaged area and add at least 2 inches. The shorter the patch is, the more visible, since the closely spaced seams draw the eye. Use longer lengths to spread apart the seams and blend in the piece. Cut the siding with either a table saw with the blade reversed, to create a smooth cut, or a utility knife. Score the siding face with the knife, then snap to create a clean break.

2. Trim the top and bottom siding edges. Cut away the very top portion, called the nail hem, as well as the curved portion of the bottom edge, known as the buttlock. Use a saw or utility knife again and cut carefully to avoid damaging the piece.

3. Secure the vinyl patch. Slip the top of the vinyl siding patch into the gap formed under the siding above the repair. Snap the body in place, over the existing siding, to create a nearly invisible repair that fits snugly. For extra strength, you can also squirt a little caulk on the back of the vinyl siding patch before fitting in place. Since the top lip is beneath the upper layer, water finds it difficult to enter the patch while the bottom edge is hidden in the recess between pieces. The siding’s design itself encourages the patch to stay in place, like building blocks fit together.

Installing a Vinyl Siding Replacement Piece

1. Unlock the damaged vinyl siding piece. Use a vinyl siding removal tool, called a zip tool, to snap the top of the piece free where it locks with the bottom of the piece above. The zip tool looks like a curved, miniature pry bar with a metal hook at top. Wedge the tip, with the curved portion pointing back toward you, under the edge of the siding piece above the damaged section. Typically, each piece of siding features small gaps or indentations under the bottom edge on either end. Start at one of these spots to make getting under the lip easier.

2. “Unzip” the top edge. Pull down with the tool to pry the top edge of the damaged siding free from the piece above. Slide the tool sideways as you pull to free the entire top lip. Think of the process as similar to opening a can of vegetables.

3. Free the bottom edge.  Repeat the process to unlock the bottom of the damaged siding from the row of siding beneath it. At this point, the only thing securing the siding is the nails at the top of the piece.

4. Remove the nails. Use a pry bar to remove the nails securing the damaged siding to the house at the top of the siding piece. Pull the piece down and away to remove. Work carefully; you want to avoid tearing holes in the house wrap beneath the siding. If you find small holes once the siding is removed, tape over them with vinyl tape to maintain the moisture barrier’s integrity. For extensive damage, hang new house wrap. While this requires removing several rows of siding for a small patch, or even removing the entire wall of siding and starting from scratch, the alternative – allowing moisture into your walls and rotting the entire structure – will cost even more in time and expense.

5. Cut the replacement vinyl siding to fit. Add 2 to 3 inches to the length needed to allow an overlap at the edges. Measure at the top and bottom of the replacement piece, connect the lines with a square or straight edge, and mark a cut guide. Use a saw, again with the blade reversed for a smoother cut, or utility knife to trim the piece to fit.

6. Fit the vinyl siding to the wall. Align the siding so it’s centered in the space with overhang on both sides. Push the piece up to encourage the bottom lip to hook around the edge of the piece below. Use the zip tool as necessary to hook the bottom edge in place.

7. Nail down the replacement strip. Use 1-inch nails to avoid penetrating the wall deeply. Drive the nails through the nail hem at the top of the siding, using the same holes the previous panel used to prevent excess holes. Don’t sink the nail head flush with the surface. Leave about a 1/32-inch gap to allow the siding to expand and contract without buckling or warping the surface. If you can’t slide your fingernail underneath the nail’s head, it’s too tight.

8. Zip the siding in place. Hook the zip tool under the bottom edge of the siding above the replacement piece. Pull the edge down and out to make it slip over and lock to the top of the replacement siding. Hit it with the palm of your hand, directly over the joint, to encourage the pieces to lock as necessary.

Tips:

Cold weather can make vinyl siding brittle. For best results, install replacement pieces during mild, dry times of the year. Use duct tape to temporarily cover large areas of damage to keep the wall dry and secure until you can repair it.

If your siding is sun-faded with age, a perfect color match is nearly impossible. Consider removing a piece of siding from an undamaged area that isn’t as noticeable. Use this piece as a replacement and place a new, unfaded piece in the vacancy left by the replacement piece.

To repair vinyl corner trim, use the same procedures as the vinyl siding patch. Cut the edges off the trim to allow it to slide over the top of the existing trim. Spread caulk on the back of the trim and snap in place.

{ 4 comments… read them below or add one }

jim gilson February 13, 2013 at 1:49 pm

I have an old garage that has faded a little and is just dirty looking. I would like to restore the finish for my father. If you have any suggestions as to what type of cleaners or maybe some kind of chemicals to make the job go well and restore the finish I would really appreciate it. Thank You Jim

Reply

Karie Fay March 3, 2013 at 12:44 am

Hi Jim,

How thoughtful of you to do that for your father!

When you say you want to restore the finish, what exactly do you mean? You won’t be able to brighten sun-faded materials, but if it’s a matter of it looks dingy and dirty, you can do that.

For ordinary dirt and cleaning, I would mix water with a good dish soap like Dawn or a laundry detergent like Tide. If you must, add oxygenated bleach like OxiClean (1 cup per gallon) but avoid chlorine bleach if you are concerned about grass and plants. Stains respond to products such as Fantastik, Murphy’s Oil Soap, Lysol or Soft Scrub. (Whenever using a new product, test it in an inconspicuous area).

Most importantly, choose your tools carefully. A power washer may have too much force — I would probably use a hose with a decent sprayer instead. Use either a soft-bristled brush or a rag and wash the house much like a car. In areas with stubborn stains, let the cleaner sit a few minutes before scrubbing.

Oh, and make sure to spray straight-on or slightly downward. If you spray up, you can easily force water behind the siding.

Hope that helps!
Karie

Reply

Carl Weaver December 18, 2012 at 10:41 am

Ms. Fay,

Enjoyed the article and have a more complex repair question. It involves replacing a vinyl siding corner piece.

Might you have a recommendation of someone who may be able to provide guidance?

Thanks for any time you invest,

Carl

Reply

Karie Fay December 18, 2012 at 11:17 pm

Hi Mr. Weaver,

What is the problem with the vinyl siding corner piece? If you can give me a little about the details, that will help. I will give it a shot and see if we can’t come up with a solution.

Thanks,
Karie Fay

Reply

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