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Understanding Your Roofing Deck Material and Shingle Installation Near Des Moines
When it comes to replacing or installing new shingles on your home in the Des Moines area, the underlying roofing deck material plays a far more significant role than many homeowners realize. This unseen foundation dictates not only the longevity and performance of your new shingle roof but also the specific installation methods and materials that must be employed by your roofing contractor. Failing to consider the deck’s composition can lead to costly errors, premature roof failure, and invalidated warranties. This article will delve into how different roofing deck materials, commonly found in Des Moines homes, influence the installation process for new shingles, ensuring a durable and effective outcome.
The Crucial Role of the Roofing Deck
The roofing deck, often referred to as sheathing or underlayment, forms the structural base for your shingles. It provides a stable platform for fasteners and plays a vital role in distributing roof loads. Its condition and material directly impact the ability of shingles to be properly secured and to withstand the elements. In Des Moines, with its varying weather patterns, from intense summer sun to heavy winter snow and ice, a robust and appropriately installed shingle system over a sound deck is paramount.
Common Roofing Deck Materials in Des Moines Homes
Historically, and in many existing homes around Des Moines, you’ll encounter a few primary roofing deck materials. Understanding these will help you communicate effectively with your roofing professional.
Solid Wood Decks
Rough Sawn Lumber: Older homes, particularly those built before the mid-20th century, might feature thick, rough-sawn planks as their original decking. These planks are typically 1 inch or more in thickness and are laid edge-to-edge or with small gaps. The rough surface can offer some grip for shingles, but its unevenness can also present challenges.
Plywood: A more common material for decks constructed from the mid-20th century onwards, plywood consists of thin layers of wood veneer glued together. It’s known for its strength and stability. Standard thickness for roofing is 7/16-inch or 1/2-inch, though thicker grades exist.
Oriented Strand Board (OSB): OSB became popular in the late 20th century and is now a prevalent decking material. It’s made by pressing together large strands of wood with adhesives. OSB is generally more economical than plywood and offers comparable strength and stiffness. It typically comes in 7/16-inch or 1/2-inch thicknesses.
How Deck Material Influences Shingle Installation Methods
The type and condition of your existing roofing deck will dictate several critical aspects of your new shingle installation near Des Moines.
Solid Wood Decks (Rough Sawn Lumber)
When dealing with rough-sawn lumber, the primary consideration is the uniformity of the surface. If the planks are heavily warped, uneven, or have significant gaps, a roofing contractor may recommend installing a new layer of plywood or OSB over the existing planks. This creates a smooth, consistent surface essential for the proper adhesion and sealing of modern asphalt shingles. If the planks are relatively flat and in good condition, shingles can sometimes be installed directly. However, specialized roofing nails designed for thicker materials and wider heads might be necessary to ensure adequate penetration into the wood without excessive pressure that could damage the planks. The gaps between planks, if present, require careful attention, and often a tightly laid felt underlayment or synthetic underlayment is crucial to prevent wind-driven rain and snow from seeping through. The rough surface can also affect the even distribution of heat, potentially leading to localized hot spots that can prematurely age shingles. Therefore, good attic ventilation is even more critical with solid wood decks.
Plywood Decks
Plywood provides a relatively smooth and stable surface for shingle installation. The primary concern with plywood is its condition. If the plywood is soft, delaminated, or shows signs of rot – especially around valleys and eaves where water tends to collect – it must be replaced. A qualified roofer will sound the deck with a hammer to identify soft spots. Standard 6-penny or 8-penny galvanized roofing nails are typically used to fasten shingles to plywood, ensuring sufficient penetration into the underlying rafters. The edges of plywood sheets should align with rafters for optimal support. If the plywood is too thin or has cupped, an additional layer of sheathing might be necessary, though less common than with rough-sawn lumber. Proper spacing between plywood sheets, usually about 1/8 inch, is critical to allow for expansion and contraction with temperature and humidity changes, preventing buckling.
Oriented Strand Board (OSB) Decks
OSB, like plywood, offers a generally uniform surface for shingle installation. The key considerations for OSB are similar: detecting soft spots or delamination, which can occur if the material becomes excessively saturated and then dries out repeatedly. If the OSB is sound, standard roofing practices apply, with appropriate nail length and placement into the rafters. OSB is slightly more susceptible to edge swelling when exposed to moisture compared to plywood, so ensuring proper overlap and sealing of seams is important. Roofers will also check for any delaminated strands or soft areas that would compromise the anchoring of the nails. When installing shingles over OSB, the goal is to ensure every nail penetrates firmly into the solid wood strands and, ideally, into a rafter or solid blocking. The smooth, manufactured surface of OSB allows for excellent shingle adhesion.
Additional Considerations for Des Moines Roofing
Beyond the type of deck material, several other factors influenced by local conditions and best practices are crucial for shingle installation near Des Moines:
Underlayment
Regardless of the deck material, an appropriate underlayment is vital. In Des Moines, with its potential for ice dams in winter, a self-adhering ice and water shield is often required along eaves, in valleys, and around penetrations. This provides an extra layer of protection against water infiltration. A high-quality synthetic underlayment or traditional felt paper is then installed over the entire deck to provide a secondary water barrier and a clean surface for shingle installation.
Ventilation
Proper attic ventilation is crucial in Des Moines’s climate. It helps regulate attic temperatures, reducing heat buildup in summer and moisture condensation in winter. This directly impacts the longevity of your shingles, as excessive heat can cause them to deteriorate more rapidly. The deck material itself can influence how effectively heat dissipates.
Nail Placement and Length
The most critical element of shingle installation is secure fastening. The choice of deck material influences the required nail length to ensure that nails penetrate through the shingle, the underlayment, and into the deck, ideally reaching the rafters for maximum holding power. A professional roofer will use a nail gun calibrated correctly for the deck material and shingle thickness, ensuring consistent and appropriate depth. Overdriving or underdriving nails can compromise the integrity of the entire roof system.
Deck Repair or Replacement
A reputable roofing contractor will always begin a shingle replacement project with a thorough inspection of the existing deck. Any areas of rot, soft spots, delamination, or structural weakness must be repaired or replaced before new shingles are installed. Attempting to re-shingle over a damaged deck is a recipe for disaster and will likely void your new shingle warranty. The cost of deck repair or replacement is an essential part of the overall roofing project budget and should not be overlooked.
Conclusion
The choice of roofing deck material is a foundational element in the successful installation of new shingles in Des Moines. Whether your home features older rough-sawn lumber, durable plywood, or modern OSB, understanding its characteristics is key. It dictates the preparation of the surface, the choice of underlayment, the type and length of fasteners, and the overall installation method employed by your chosen roofing contractor. By prioritizing a thorough deck inspection and addressing any necessary repairs or replacements, you ensure that your new shingle roof will provide reliable protection and aesthetic appeal for years to come, weathering the unique meteorological challenges of the Des Moines region.
Frequently Asked Questions
What is the most common roofing deck material in Des Moines homes?
The most common roofing deck materials found in Des Moines homes are plywood and Oriented Strand Board (OSB), with older homes potentially having rough-sawn lumber.
Can shingles be installed directly over old, uneven wood planks?
Possibly, but it’s often not recommended. If the planks are warped or uneven, a new layer of plywood or OSB is usually installed on top to create a smooth, stable surface for the shingles. This ensures proper adhesion and prevents premature wear.
How do I know if my roofing deck needs to be replaced?
A professional roofer will inspect the deck for soft spots, rot, delamination, or sagging. You can also sometimes detect issues by walking on the roof (carefully!) and noticing flexibility or sponginess. Water stains on ceilings or attic moisture can also be indicators.
Does the deck material affect the type of nails used for shingles?
Yes, the thickness and density of the deck material can influence the required nail length to ensure proper penetration into underlying rafters. Professional roofers use calibrated nail guns to achieve the correct depth.
What is the lifespan of different roofing deck materials?
When properly installed and maintained, plywood and OSB can last for the lifetime of several shingle roofs, often 20-30 years or more. Rough-sawn lumber can also be durable but is more susceptible to moisture-related damage if not properly sealed and ventilated.
Is underlayment always required, regardless of the deck material?
Yes, an underlayment is always a crucial component of a shingle roof system. It acts as a secondary water barrier and protects the deck from moisture. In Des Moines, installing self-adhering ice and water shield is also highly recommended for critical areas.
What happens if new shingles are installed over a damaged deck?
Installing shingles over a damaged deck can lead to premature roof failure, leaks, compromised structural integrity, and will almost certainly void your new shingle warranty. The fasteners won’t have adequate holding power.
Should I factor in potential deck repairs when budgeting for a new roof?
Absolutely. A thorough deck inspection is standard practice. It’s wise to budget for potential repairs or replacement, as identifying and addressing deck issues proactively will save you significant costs and headaches in the long run.
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