What causes roof decking to warp?

Common causes include: Uneven Rafter Levels: If a roofer installs a roof deck without ensuring the rafters are even, warping often occurs. … Water Damage: Plywood in a roof deck creates a warped effect when holes in the exterior allow water inside your home. Poor installation may also create movement in the plywood.

What causes ripples in a roof?

Lack of adequate ventilation could lead to moisture being trapped in the roofing system. The sheath absorbs this moisture causing it to ripple. … Moisture from the house will get in between the panels and absorbed by the felt. The felt with then expand and wrinkle pushing the shingles up causing the rippling effect.

How do I know if my roof deck needs replacing?

These common signs of damaged roof decking include:

  1. Visible holes in your roof.
  2. Signs of mold or mildew in your attic.
  3. Missing shingles.
  4. Roof sagging that’s visible from the exterior or interior.
  5. Curling and/or buckling shingles.
  6. Shingles that are wearing in a granular pattern.
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How do you fix a buckled roof?


  1. Allow moisture to escape the roofing system. …
  2. Remove the shingles that are affected, and if the felt is wrinkled repair the felt wrinkles by cutting and re-nailing the felt so that it’s flat and replace the shingles.
  3. Ensure that the attic is properly vented.

What does a wavy roof indicate?

What Makes a Roof Go All Wavy? A wavy roof is rather alarming, and unfortunately there are actually quite a few potential causes. However that pronounced wave will nearly always signify one big thing: your roof is buckling or bulging somewhere, or the materials simply aren’t lying flat.

Is it OK to shingle over wet felt?

Do not shingle over wet or damp roof sheathing or damp felt paper. The trapped moisture cannot evaporate when the sun heats the shingle. … Stripping away the old shingles will cost more, but the new roof covering will last longer if it is a single layer.

Why does my new roof look wavy?

When heated by the sun, the strip will cause the shingles to lay down and bond together. It is not uncommon for a new roof to look a bit wavy until this permanent seal is created. This is normally not a problem unless you experience windy conditions that can catch the shingles.

How much does it cost to replace roof decking?

Across the US, homeowners report spending around $750-3,000 on deck replacement cost, depending on project size and materials. In fact, the price range is so spread out, because the quality of deck materials ranges from very low to top notch.

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How long does it take to replace roof decking?

Small homes that are less than 1200 square feet are usually done in a single day. However, for larger homes that have more ridges and valleys the time can go up. Although, barring any other problem, most home less than 4,000 square feet can be done in three days or less.

What is best for roof decking?

Oriented strand board (OSB) – OSB is the most common type of material used for roof decking. It’s durable and readily available, and has relatively low costs. OSB is made of interwoven strands of wood bonded with adhesive. … This type of decking is used on roofs that do not have a ceiling.

Can you roof over wet plywood?

A: It is never a good idea to install a roof over wet plywood or any type of roof sheathing. Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the steam finally escapes.

What does a buckled roof look like?

Buckling shingles look like something is underneath the shingles pushing them upward. You also may have curling shingles, where the center of the shingle looks concave and the edges turn up. Both issues are noticeable from ground level and require the attention of a qualified contractor.

How much does it cost to fix sagging roof?

Sagging Roof Repair Cost

Repairs for a sagging roof average $750 to $2,000. This can be one of the most expensive roof issues to fix. A sagging roof is usually caused by a buildup of water or snow on the roof, putting pressure on it and damaging the shingles and boards lower down.

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Should roof shingles lay flat?

Shingles should be butted snugly side-by-side in each horizontal row. Lapping the shingles can prevent the shingles from sealing. Before hiring a roofing contractor, ask for references to ensure the contractor is reputable.

Why does my roof have bumps?

What causes bumps on your roof? … These long raised up sections are from improperly nailed roof decking. If your home has plywood decking below your shingles and the plywood was not nailed properly. In time the decking will start to warp and curl on the ends causing these raised sections.

Why does my metal roof look wavy?

One issue that occurs with metal roofs is oil canning or stress wrinkling — that wavy appearance you see in the roof panel on the left side of the above photo.

Roofs and roofing