Scorching heat, strong winds, snow loads and driving rain can all cause significant damage to your roofing shingles. But the problems don’t end there. The structural component located right under your shingles called the roof decking is also susceptible to damage. A bit of damage to the decking might not seem like a pressing matter to some people, but it can lead to a series of structural issues and expensive repairs if left unchecked.
What Is Roof Decking?
Like the shingles, the roof deck – also known as sheathing – is a critical element to the structural integrity of the roofing system. It refers to the layer of materials located above the rafters and below the underlayment, which is installed directly beneath the shingles. In residential applications, roof decking is typically made from plywood or oriented strand board (OSB). In some older residences, the roof deck is built with wooden boards that are connected using either the tongue-and-groove or butt-joint method.
The roof deck is what ties all the roofing components together. That said, it must be sturdy enough to support the weight of the shingles while being flexible enough to bear the harsh changes of the seasons. It also helps regulate the moisture levels inside the home by allowing excess moisture to escape through the attic and keeping rain and snow out. Overall, it assists the underlayment in ventilation and moisture protection.
What Are the Different Types of Roof Decking?
In most cases, roof decking is made from plywood or a plywood composite called OSB. OSB consists of interlocking wood strands compressed together by a waterproof resin. Because there are no internal gaps, the panels are water-resistant. OSB decking can also be manufactured to match desired strength, thickness, rigidity and panel size. It is the more popular option due to its low price point. When it comes to moisture protection, however, plywood holds a clear advantage. It dries out more quickly than OSB, so swelling is not likely to affect the finished roof. It is also approximately two pounds lighter per sheet than OSB, meaning the subflooring panels do not need to be as thick.
How Can Roof Decking Get Damaged?
Since roof decks are made from wood and wood composite materials, they are particularly vulnerable to rotting and other forms of water-related damage. Old shingles, overflowing gutters, torn flashing and ice damming can all allow water to seep into your roof. Damage can also occur in areas where shingles are cracked, curling or missing as a result of ultraviolet deterioration, powerful winds or old age.
Excess moisture in the attic due to insufficient ventilation can also lead to a damaged roof deck. A hot and humid attic can cause the wooden boards of the decking to warp and decay over time. Another common cause of damage to roof decks is the improper installation of solar panels on the roof. A solar power system is a great way to cut down energy costs while minimizing your carbon footprint, but roof-mounted solar panels can be pretty heavy. All that extra weight – around 40 pounds – can cause the decking to split or bow. But as long as your installer is licensed and qualified, installing solar panels will not result in roof damage.
Most residential roofing systems like asphalt shingles are designed to last around 20 years, although the actual service life depends on many factors, including quality of materials and installation, preventive maintenance and the local climate.
What Are the Signs of Damaged Roof Decking?
A roof leak is one of the most common signs of a damaged roof deck, and it can lead to a host of other problems, such as stains or discoloration on ceilings and walls, cracked or bubbling paint, peeling wallpaper and wet floorboards. With a brief inspection of the attic, you might also uncover water stains on the rafters and in the insulation or daylight passing through gaps in the roofing structure. If left untreated, a damaged roof deck can let mold and mildew grow and fester, affecting walls, ceilings, insulation and stored items in the attic. A sagging roof is also an indication that there is a major problem with the roof deck. Other easy-to-spot signs you need to watch out for include missing shingles, severe granule loss, and deterioration around vents, chimneys, skylights and other fixtures on the roof.
Because your roof is your primary defense against year-round elements, the National Roofing Contractors Association (NRCA) recommends inspecting your roof at least twice a year – once in the fall when the heat has subsided and once in the spring when snow and ice have melted away – to make sure everything is in tip-top condition. It is also advisable to conduct inspections after serious weather events, such as a hailstorm, so you can catch small issues before they spiral out of control.
Should Roof Decking Be Repaired or Replaced?
For some homeowners and building owners, it is quite tempting to install a new roof covering over their old roof decking instead of getting a complete roof tear-off because it saves time and money. If your roof deck is affected by rot, a repair or re-roof is simply not an option. Instead, it must be fully replaced. The longer you go without replacing a damaged roof deck, the more problems it can create, resulting in even costlier repairs down the road.
Of course, it is important to spend within your means when it comes to home maintenance. However, you also need to consider that deferring urgent replacements, such as tearing off a rotted roof deck, can ultimately affect the rest of your home. Most of the time, a roof deck replacement is localized, which means only areas of damaged wood are replaced and not necessarily the entire decking.
How Do You Protect Your Roof?
You can avoid all the headaches that come with a damaged roof deck by maintaining your roofing system. Here are some tips:
- Keep the gutters clean. Many people overlook their gutter system when it comes to roof maintenance, but it is an important facet of the roofing structure. When gutters are clogged with leaves, twigs, birds’ nests and other debris, the runoff from the roof is not able to successfully drain away from the home. Instead, it spills to the sides of the gutters, destroying the landscape around the home, or backs up to the roof and seeps underneath the shingles, affecting the decking and creating leaks. Experts recommend having your gutters cleaned in early spring and early fall.
- Keep tree branches trimmed. Overgrown trees can scrape the protective granules off your shingles, diminishing their ability to combat ultraviolet (UV) rays. Overhanging branches are also a means for squirrels or rodents to access your roof. As a general rule, make sure to keep a 10-foot distance between your roof and the surrounding tree branches.
- Prevent ice damming. When a snowstorm hits your area, do not let snow build up on top of your roof to prevent ice damming, water infiltration or even roof collapse. If ice has already formed, do not carelessly pry it off using a roof rake. Instead, contact a roofer to deal with it properly. Keeping your attic adequately insulated is also crucial when preventing ice dams.