Home with Vinyl Siding

How To Fix Sagging Vinyl Siding (Step-by-Step)

In Construction by Giovanni ValleLeave a Comment

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Vinyl siding does more than just making your home’s exterior look good. It keeps your house watertight and keeps pests, fungi, mold, and mildew at bay. Because of that, when your vinyl siding loosens or sags, it’s best to fix it immediately so you don’t forego its benefits.

To fix sagging vinyl siding, first identify the cause and the severity of damage to the wood underneath. After that, remove the siding in the reverse direction of how it was installed. Finally, nail the loose part and snap the bottoms of the upper rows into the tops of the lower rows.

Sagging siding comes with devastating consequences, such as termite damage, peeling interior paint, and higher electricity bills. Therefore, it’s advisable to inspect your vinyl siding frequently and repair it whenever necessary. Keep reading for the causes of sagging, its effects, and how you can fix it in 4 simple steps.

What Causes Vinyl Siding To Sag?

My two cents is that solving a problem requires one to know its cause(s). Most notably, it becomes easier to prevent it from recurring. Therefore, before we dive into the steps you need to follow to repair sagging vinyl sides, let’s examine some of its common causes.

Poor Installation

Poorly installing your vinyl siding is a sure-fire way to invite most of the problems homeowners encounter, such as bulging and cracking. As a rule of thumb, you should comfortably move any siding by about ¼ to ½ in. (6.4 to 12.7 cm) horizontally. If you can’t, either the nails aren’t properly placed, or they’re too tight.

As a result, the siding may buckle, warp, or sag.

Poor Quality Material

Most people often overlook this, but the truth is poor-quality siding tends to sag faster than superior ones. More expensive, high-quality sidings are made of insulated PVC. They’re thicker and don’t sag, even when temperatures are extremely high.

Conversely, cheaper, low-quality, and thin vinyl siding perform poorly. Even a slight temperature change may force you to replace the entire siding.

Nearby Heat Sources

Suppose you love grilling during summer and use your garage as your grill’s storage. In that case, there’s a pretty high chance you’ll discover the vinyl siding melting, causing sagging. Heat from nearby objects, like grills, can easily cause your siding to loosen. Therefore, it’s best to let your grill cool down before storing it anywhere near the sidings.

Also, UV reflection from a neighbor’s windows can produce enough heat to cause vinyl siding to sag. Chat with your neighbor to come up with solutions to diffuse the UV rays, such as installing screens, to make it less intense by the time it reaches your siding.


Moisture is one of the primary causes of siding sagging and other problems, such as mold and mildew. If your home’s exterior doesn’t have sufficient water protection, water may penetrate the siding, causing warping. To mitigate this, you could install a plastic house wrap designed to keep your home’s structure waterproof.

If you find mold or mildew, hire a professional to power wash and it blast away from your siding.

Building Movement

As buildings age and settle, their structures tend to shift. These changes may cause the siding to sag. In some cases, loose panels and siding may be tell-tale signs of more critical structural problems in your house’s construction.

Reach out to a relevant engineer if you suspect your building’s structure needs to be repaired.

How To Fix Sagging Vinyl Siding (Step-by-Step)

Fixing loose or sagging siding isn’t as complicated as many people think. Assuming the damage isn’t that much, a hammer and a few nails will do the trick. However, if you notice any structural damage, it’s best to call an expert, such as an engineer.

To fix your sagging siding, follow these steps:

1. Identify the Cause of the Sagging

Check for potential causes of sagging (as discussed above) to determine the best step to take before fixing the siding. If you notice major problems, like wood rot or termite damage, you may need more than a hammer and nails to repair your vinyl siding. It’s best first to remove the siding covering the affected area and replace the damaged wood.

2. Remove the Siding

Remove your vinyl siding in the opposite direction of how it was installed. Under normal circumstances, siding is installed from the bottom up. The panels usually have rows of slotted holes at the top.

Use a hammer to pull the top row of nails. After that, unsnap the siding’s top row. Working your way down to the sagging part, remove all newly exposed nails.

3. Nail the Loose Portion

Once you’ve reached the sagging portion of the siding, check for any signs of rotting. If the wood is still in good condition, nail this portion. Ensure the space between nails is 16 to 18 inches.

Leave the nails sticking out by about ⅛ in. (3.2 mm) from the wall. This gives room for the siding to contract or expand due to temperature change without causing problems.

4. Replace the Upper Sections

Once you’ve reattached the loose section, replace the section above it. You can do that by snapping the bottom of the upper part into the top of the lower row. Ensure there’s about ¼ inch space at the end of each row to allow the panels to slide back and forth freely.

Nail the upper row, ensuring the nails aren’t too tight. For the best results, drive the nails into fresh material.

Pro Tip: Ensure the upper rows are firmly snapped into the lower rows. Also, the rows should be straight before nailing, and the ends should overlap properly.

Risks of Sagging Vinyl Siding

To illustrate why you need to fix your siding urgently, let’s discuss the risks that come with leaving it loose or sagging.

Water Damage

Sagging vinyl siding is highly susceptible to water damage. It leaves gaps that water can flow through freely, reaching your home’s walls. Besides damaging your interior walls, the water may cause irreversible damage to your siding panels.

Always check for bubbles in the siding. The presence of bubbles indicates water is trapped beneath, and you may need to replace the siding.

Peeling Paint

Although it may not be obvious at first, peeling paint and loose wallpaper are signs of faulty vinyl siding. If water seeps through the siding, it may leak into the wallboard and damage your home’s interior. Also, sagging siding may force you to paint the exterior more frequently, often within six years.

High Electricity Bills

Faulty siding can increase your energy bills. When it sags, it leaves spaces for the circulation of warm and cold air between the interior and exterior of your home. As a result, your home’s insulation reduces, pushing your HVAC system to do more work.

The result? A dramatic increase in your heating and cooling expenses.

Experts advise that you regularly inspect the siding, including where it connects with your roof, to check for leaks.

Vermin Infestation

If you leave the vinyl siding sagging, it may form gaps, allowing vermin to access your home’s structure easily. Pests like termites can cause severe structural damage to your home. To check for termite, take a screwdriver and push its tip against the siding.

If you can push the screwdriver tip into the siding effortlessly, there’s a high chance that termites have damaged it.

Mold and Mildew

As I mentioned earlier, the sagging vinyl siding makes your wallboard susceptible to water penetration. When water penetrates the siding, it creates the perfect condition for fungus, mold, and mildew growth.

The fungus, mold, and mildew pose a health hazard to you and your loved ones. They can cause coughing, wheezing, allergic reactions, and a running nose.

To rid your siding of these unwanted guests, I recommend that you use the Wet and Forget Stain Remover from Amazon. This cleaner doesn’t require scrubbing, power washing, or rinsing to work. Simply spray it on the affected surface and wait for the results. It’s also non-acidic, biodegradable, and bleach-free.

Your Home Loses Its Aesthetic Appeal

If you don’t fix or replace siding, your home may lose its visual appeal. Your home’s degraded appearance may become an eyesore to you and your family. Also, you may find it difficult to sell your home.

Safety Hazard

If you keep procrastinating instead of addressing the problem, so much water may leak into your siding that it may start to rot and decay. When that happens, the siding can easily rot, decay, and become loose.

Such damage can cause your vinyl siding to fly off during storms or high winds. It may hurt you, your neighbors, or damage their property, posing liability issues.


Properly installed siding prevents water leakage into your home’s structure. If you leave your siding sagging, you could eventually experience rot, mold, mildew, or structural damage. Additionally, it can easily become a hiding place for destructive vermin.

Besides, by not fixing vinyl siding problems at the right time, you risk getting it blown away by strong winds – this poses the risks of bodily injury and property damage. As a result, it’s essential to follow the steps I’ve highlighted in this article to ensure your siding is installed properly. However, if you spot other serious issues, contact an expert immediately.


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