(316) 927-2233Your roof is only as strong as what’s beneath it. Compromised decking puts every shingle above it at risk, and roof decking replacement is a significant repair. If done incorrectly, it can lead to leaks, sagging, or even structural failure.
That’s why we strongly recommend consulting with professional roofers before attempting any decking replacement. However, if you’re an experienced DIYer or curious how roofers replace decking, this guide will walk you through the process, from identifying damaged decking to installing replacement decking.
How to Prevent Decking Damage
The best roofing problems are the ones you never have. Considering the nuances while designing a roof allows those nuances to save you time and money in the future.
Adequate attic ventilation
Maintaining proper attic ventilation is a code-mandated nuance that prevents moisture buildup beneath the roof deck.
Like the Ridley Scott movie Alien, the real threat to decking is what’s on the inside. An inadequately ventilated attic reduces roof life by 24 percent. This doesn’t account for side-effects like ice damming, which commonly presents rotted decking at the eaves and rakes. The closer your attic is to the ambient temperature, which is the temperature of the surrounding air, the less likely ice dams and other damages are to appear. Pairing up-to-code attic ventilation with ice and water shield protects your roof’s perimeter, decreasing the likelihood your decking will need repairs in the future.
Moisture Damage at Eaves
Moisture Damage at Eaves
Moisture Damage to OSB
Ice and Water Shield at the Eaves
Address leaks immediately.
The quicker leaks are addressed, the less likely water is to permeate the underlayment and saturate your decking.
Roof damage starts the countdown for decking damage. The longer damage remains unaddressed, the higher the likelihood that decking damage is to occur. Underlayment and, depending on the area of the roof experiencing damage, ice and water shield, will protect your substrate temporarily. Address damage quickly so that your underlayment remains a redundancy, not your primary defense against water.
The countdown applies to most types of damage. The best practice is to schedule routine inspections or roof tune-ups to preempt more extensive damage to decking.
If you’ve read a workmanship warranty for home exterior products or services, there’s always an exclusion for damage caused by your home’s foundation. That’s because foundation damage manifests everywhere.
To put it another way, think of it like time: you can’t see or feel time, but you know it exists because you experience its symptoms. Decking damage is the same. It produces symptoms in your shingles, flashing, fascia, rafters, ceiling – everything is affected by decking damage, even if you can’t see it. It’s your roof’s foundation, which is why timely repairs are critical.
When to Consider Full Deck Replacement
If at least 30 percent of your discovered decking show signs of deterioration, or if you notice widespread sagging across multiple structural beams, you should expose more decking to determine the extent of damages.
Even when only 5 percent of your decking is damaged, it still requires replacement. The 30-percent rule is used as a threshold to inform roofers when further inspection of the decking is needed. If 30 percent of your decking is damaged, it’s less likely to be isolated damage.
A benefit of hiring a professional to perform decking repairs is simply not being on the hook for more extensive repairs than you expected. During a re-roof, our crews are prepared to handle decking repairs they discover. Discovering more extensive damage during a DIY repair can leave the roof exposed while additional repairs are coordinated.
Step 1: Inspect the Roof for Signs of Damaged Decking
Decking damage is nearly impossible to confirm without unobstructed visual confirmation. However, some symptoms are highly suggestive of decking damage. These are clues, cues that tell you to confirm the damage visually.
Severely Buckled Decking at the Eaves under Shingles
Inconsistent Substrate Visible Under Shingles
Severely Buckled Decking at the Eaves
Buckled Plywood Decking
H-clips are often inserted between deck boards to provide a 1/8-inch gap. This is the same principle as ring sizes being slightly larger than finger diameter: it prevents temperature fluctuations from causing critical failures. For a ring, it can get stuck on your finger. For boards of wood decking, they can buckle, bursting up or down at the seams due to temperature-caused tension. Usually H-clips will be enough to prevent buckling. Swelling from absorbed water or extreme temperature fluctuations, even for Kansas, push the limits of that 1/8-inch gap.
Lack of underfoot rigidity: Your roof should feel as solid as the ground below it while you’re walking on it. In some instances, walking on your roof can reveal decking that’s been saturated with water. A soft spot beneath your feet is likely to be caused by rotted decking. If possible, always confirm decking damage from the attic.
Discoloration: Sun bleaching is normal, but bleaching doesn’t darken shingles like excessive trapped moisture can. When water infiltrates the decking, its presence and eventual evaporation can work its way back up into the underlayment and eventually the fiberglass matting of the shingles.
The only way to know with certainty that you’ve identified the extent of the damage is to remove the roofing materials on top of the decking. This is a critical consideration that makes DIY decking repairs difficult.
Once suspected damaged decking has been identified from the roof’s surface and the attic when possible, it might be helpful to outline the area with chalk. While you’ll remove the roofing material in the next step, an outline to define the damaged area can prevent the unnecessary removal of roofing material.
During your attic inspection, note the location of your structural beams. This will be important when you begin cutting out the damaged decking.
Step 2: Remove Roofing Materials to Expose the Deck
Carefully remove all shingles, underlayment – any roofing material that obstructs the damaged decking. Take your time removing the material. The shingles, underlayment, and any healthy decking will be reused, so they should be preserved during removal.
If you’re replacing decking at your eaves or valleys, it’s likely to have ice and water shield. Ice and water shield is a self-adhering waterproofing membrane that is applied directly to the roof deck. Once removed, it won’t reattach properly, so re-application of the same material will be ineffective. Instead, purchase a new roll and install a fresh layer before adding underlayment at step 6.
Decking repairs at the eaves will usually require the removal and reapplication of the starter course and drip edge, too.
- A starter course comprises shingles applied to the perimeter of a roof beneath the first row of shingles to optimize alignment and wind resistance.
- Drip edge is corrosion-resistant metal flashing that protects fascia and the substrate by directing water away and blocking wind-driven rain.
Step 3: Cut and Remove Damaged Decking
While the damaged decking is clearly visible now that it’s exposed, it’s useful to chalk the area that you will be cutting out. It’s much easier to color in the lines when those lines are clearly defined. This will also make the installation of replacement decking much easier by maintaining sharp cut lines.
Prior to cutting, ensure that your circular saw is set to the correct depth. Most decking for asphalt shingle homes is 7/16-inch thick, but this should be verified prior to cutting. This can be done by removing a stray nail and measuring the hole’s depth or by boring one yourself. Once you’ve identified the decking’s thickness, set your circular saw’s depth accordingly. With excessive depth, you risk cutting into your roof’s structural members.
Using a circular saw, cut along the chalk lines. Follow the natural seams between boards when possible to simplify both removal and the installation of new decking. Carefully avoid hitting embedded nails in the decking.
Make note of any fasteners that pull out.
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- Decking fasteners in healthy decking: When you’re removing the damaged decking, adjacent healthy decking might have fasteners pull out from the rafters. Before replacing the damaged decking, these need to be hammered back in to level the substrate.
- Fasteners from roofing materials: When shingles and underlayment are stripped, their original fasteners typically 1) remain embedded in the decking, or 2) get pulled out. These fasteners are not reused. New fasteners are always used when reinstalling roofing materials.
Step 4: Inspect the Substrate and Structural Members
Now that the damaged decking is removed, inspect the rafters and adjacent decking for damage or loose fasteners. If you notice damaged rafters or trusses, contact a professional immediately. We’re not structural engineers, but the most common fixes for damaged rafters are cited below.
- Sistering: This supports the rotted rafter with a new piece of wood. This is the most common solution for rafters with localized damage.
- Replacement: This option is as undesirable and involved as it sounds. Ideally “replacement” refers to a portion of your rafter. Otherwise, if the length of your rafter requires replacement, contact a professional immediately.
- Reinforcement: While sistering refers to adding an additional rafter to the existing rafter’s damaged area, reinforcement refers to bracing areas with limited damage with metal straps or plates. If the damage is localized, this can offer adequate support for your damaged rafter.
Any visibly damaged decking will need to be replaced. Rotted or delaminated decking is called “unnailable” for a reason: fasteners can’t reliably secure to damaged substrate. This presents vulnerabilities to water infiltration and wind uplift. Material warranties also require solid, nailable decking.
Step 5: Cut and Install Replacement Decking
Replacement decking should match the thickness of your existing decking. The overwhelming majority of asphalt shingle roofs utilize either 7/16-inch OSB or 15/32-inch plywood. Refer to your existing decking’s thickness from step 3 to be certain that your replacement decking’s thickness matches your existing decking.
Unnailable Decking Removed
Replacement OSB Placed
Fastener placement for decking is like taping a poster to a wall. You apply more tape around the edges so it stays taut without curling, while the middle can be secured with less tape. Decking requires double the fasteners along supported edges for the same reason: it prevents uplift and movement.
Nails should be hammered flush against the surface, but not excessively driven. Aggressively hammering in nails presents the risk of damaging the sheathing. No different than drywall, don’t excessively drive the nails.
Step 6: Reinstall Underlayment and Shingles
Once the new decking is secured and level, reinstall the underlayment and shingles.
Decking repairs performed at the eaves or valleys of a house will require ice and water shield, as described in step 2. This will be applied before reinstalling underlayment.
For decking repairs at your roof’s perimeter, the starter course is installed after the underlayment but before the first row of shingles. Drip edge is installed over the underlayment at rakes and beneath the underlayment at eaves.
After reinstalling the roofing material to manufacturer’s specifications, check for gaps and secure any exposed fasteners with sealant.
Key Takeaways
- Apparently minor problems often signal deeper issues. What looks like surface damage—soft spots, shingle buckling, or staining—can originate from compromised decking or even structural elements beneath.
- Prevention is cheaper and easier than repair. Proper attic ventilation, routine roof tune-ups, and prompt leak fixes can extend the life of your roof by years and help you avoid unexpected decking repairs altogether.
- Precision is prudent. Nuances like material thickness, fastener spacing, and even saw depth are important considerations that ensure a stable surface. Errors during repairs can ripple upward into each successive roof layer.
- DIY doesn’t mean that you’re on your own. Knowing when to consult a professional can protect your work and guarantee long-term performance.
Decking repairs are demanding. As the foundation of your roof, they require proper fastener placement, precise measurements, and soft eyes that can spot deficiencies in structural members or nearby decking throughout the process. This is why professional roofers undergo extensive training: the details matter.
Your roof deck is the foundation of your roof. When it performs well, it’s invisible. When it fails, its symptoms can be hard to miss.
This article is part of our ‘How To’ Series. Learn more about:
Installation of Roof Components
Building Science & Roofing Systems
Home Insurance
Inspection & Hazards
