You’ve opted for a roof replacement. After obtaining multiple estimates, several roofing companies recommend the removal of your existing roofing material and the installation of plywood as a replacement. If you’re curious about why it’s not feasible for your roofers to just add new shingles and roofing components on top of your current roof deck, one of the primary explanations is that your roof deck is constructed using shiplap.
Back in the 1950s and 1980s, before plywood became a common feature in new constructions, shiplap roof decking was widely utilized. Many homes built over thirty years ago still have shiplap beneath their roofs, as it was originally designed to support asphalt shingles during its early manufacturing days.
Today, shiplap is considered a challenge to asphalt shingles. Most roofing shingle manufacturers do not provide warranties for roofs that are installed directly on top of shiplap.
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Shiplap Roof Decking: An Overview
Shiplap can be discovered beneath the roofs of numerous homes that are approximately thirty years old, and it was originally tailored for the use of asphalt shingles during its early manufacturing phase. In present times, asphalt shingles are generally not compatible with shiplap. In fact, most shingle manufacturers do not extend their warranties to roofs that are directly installed on shiplap decking.
The challenge of directly installing shingles on this substandard roof decking primarily arises from the expansion and contraction of the shiplap. Each shiplap board expands and contracts during the winter and summer seasons. As a consequence of this movement, roofing nails or staples may gradually work themselves out of the roof deck over time.
Why Do You Need To Repair Or Replace The Shiplap Roofing?
One of the primary challenges in directly applying shingles onto this substandard roof decking is the inherent movement and shifting of shiplap.
As the seasons change, all shiplap boards undergo expansion and contraction, with varying degrees of movement. Consequently, shingles can shift unexpectedly, leading to roofing nails or staples gradually loosening from the roof deck over time.
In some instances, we’ve observed roofing nails piercing through the surface of asphalt shingles, and in more severe cases, the entire roof decks can suffer damage, resulting in numerous leaks and water-related issues. Over time, the shiplap fir wood resin diminishes, causing the boards to shrink, develop splits, form knot holes, and become exceedingly brittle.
This process creates gaps between the once snugly fitted shiplap planks. When roofing underlayment is directly placed on top of the shiplap, it can sag and eventually lead to leaks.
A Few Reflections Before Revamping The Shiplap Roofing
The presence of shiplap on your roof is a strong indicator that the roof deck is at least half a century old. Over this extended period, the wood has significantly dried out, making it extremely brittle.
The presence of gaps produced between shiplap boards is the potential source of water intrusion and leakage. These boards are responsible for development of knot holes and cracks, which accumulates the further risk of cracks and ultimately leakage.
In cases where additional shingles were added to the original roof, a new under layer may have been used to conceal the aging shiplap, which tends to deteriorate over time.
Each new layer of roofing introduces fresh nail holes into the underlying layers. Henceforth, responsible for leakage that arises from these fractures, holes etc.
The nails used to protect the roof during the construction of new roof on the existing shiplap do not goes beyond through the shiplap.
The vulnerability of damage and leakage is due to non-adherence of proper anchoring to roof .
Steps To Repair The Shiplap Roofing
During the installation of new asphalt composition shingles, electro-galvanized roofing nails penetrate the shiplap, often causing the boards to crack or split and hindering the creation of an effective seal.
As the newly installed tiles expand and contract, these nails tend to protrude upward.
The leakage tends to responsible for infiltration of water is due to elevated nails heads,
Inadequate attachment may also make your shingles vulnerable to being blown off the roof during gusty winds.
Collect Needed Tools And Supplies
- Solid shiplap roof Sheathing
- Shiplap underlayer
- Shingles
- Screws
- Power drill
- Nails
- A nail gun
- Vapor barrier
- Exterior-grade plywood
Go For The Solid Sheathing
Why risk installing a roof with a 50-year warranty, only to potentially encounter leaks within a few years? Your best course of action is to ensure a robust sheathing layer is placed over the existing shiplap, providing a secure foundation for your roofing system.
It is advisable to opt for exterior-grade OSB boards or genuine CDX plywood for this purpose.
Apply An Underlayer Over The Shiplap
An alternative and widely adopted approach is to introduce an underlayer over the shiplap, a material susceptible to degradation as it ages, especially if additional layers of shingles were previously added to the original roof. Older roofs often exhibit multiple layers of shingles, each layer punctuating the layers beneath with nail holes. With each new opening, crack, or void, the risk of roof leakage is amplified.
Another issue associated with constructing a new roof over shiplap is that the nails securing the new roof do not embed themselves into the shiplap, leaving the new shingles inadequately fastened to the roof.
The new shingles will damage and is responsible for leakage to develop due to acquiescence of rain and wind penetration
Install New Substrate
Addressing these challenges, one option is to undertake a complete roof replacement, starting anew with a fresh substrate, a vapor barrier, and new shingles.
Henceforth, the removal of shiplap is quite laborious job along with cost associated to do this job is also quite high.
A more efficient and cost-effective alternative is to directly re-sheet over the existing shiplap using exterior-grade plywood.
The approach used here is well established by the roofing manufacturers and in accordance with the codes of building construction. Anyone who opt this methodology, will have a robust surface comprising of new shingles and endurances of leakage free for many years and safe as well.
It is worth mentioning that your living should be secure and safe from leakage and is one of most prestigious assets in your life.
