Can You Put New Shingles On Top of Old Ones?

When the time comes to replace an asphalt shingle roof, you have to decide whether to remove the old shingles or install the new materials over the old ones. According to Texas roofing codes, a roof re-cover is permitted if the existing roof doesn’t already have two or more layers of covering. Therefore, if your structure has one layer of shingles, you can choose to install new shingles over the old ones. 

Why Do I New Roof Shingles?

Roofing over existing shingles may seem attractive because it eliminates the cost of tearing down and disposing of the old roofing materials. However, it can cause problems for your new structure and lower its life expectancy. Below are three potential issues that may arise if you apply new asphalt shingles over the old ones.

Can You Put New Shingles On Top of Old Ones?

Hidden Rot and Moisture Damage

One of the primary causes of asphalt roof failure is moisture damage. Missing or broken shingles leave gaps on the surface, allowing moisture to infiltrate the roof’s underside. If the structure has no underlay, moisture will damage the decking and joists. Moisture damage causes rot and mold growth on a roof frame, which compromises its structural integrity.

Roofing over existing shingles prevents your roofer from examining the condition of the roof and unearthing hidden damage. Consequently, rot, moisture, and mold destroy the roof from the underside, leading to failure and costly repairs. Therefore, remove the old asphalt shingles to reveal hidden damage that may affect the new roof’s performance. Replace worn structural elements before installing new asphalt shingles. 

Poor Performance Due to Inadequate Preparation

Before installing new roof shingles over the old ones, you must ensure that the old layer is intact. The vents, ridge caps, and flashing should remain in place to hold down the old shingles. This prevents you from adequately preparing the roof surface for the new installation. Inadequate preparation can cause the new roof to fail before the end of its usable life. 

A complete removal allows you to prepare the structure before installing the new residential roof shingles. You can remove old vents, ridges, and sealants, replace worn insulation, and even install a new underlay. Consequently, the new asphalt roof will last longer and provide optimal performance even in inclement weather. 

Roof Leaks and Diminished Aesthetics 

Curled or warped shingles can prevent the new roof from lying flat on the deck. This leaves small gaps between the layers, causing the new roof to appear rough and uneven. The small gaps between the shingles allow moisture to leak into the roof’s underside. An uneven surface can also make the roof look unappealing and poorly constructed. 

Removing all the old and worn shingles leaves a clean, flat surface for the new roof. The new materials follow the natural slope of the roof, which improves the structure’s water-shedding capabilities and boosts curb appeal.

Roofing over existing shingles isn’t wrong, but it can undermine the performance and durability of your new roof. A complete tear-off will guarantee longevity and optimal performance. Contact us today at Starr Roofing & Exteriors for professional roof replacement services.

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