A tile roof adds beauty, protection, and value to your property. What’s the best tile underlayment for California? Tile roofs are perfect for residential roofing because they withstand heat, sunlight, and the occasional summer storm.
A roof’s purpose is not only defined by choice of material on the roof but also by the underlying roof materials. Climate can damage tile roof underlayment (the layer of material between the roof deck and tile).
You can evaluate if a tile roof is ideal for you based on the underlayment’s longevity and replacement cost. A properly installed tile roof in California will provide protection from the elements and increase the value of your home.
What is Tile Roof Underlayment?
If you want to keep your roof and home safe, you need to think about what’s below the tile you choose. Roofing underlayment for tiles is found in a few distinct varieties.
- 30-pound felt paper is a favorite choice among many roofers because it is reasonably priced and effective for most jobs.
- Some roofers choose to use non-bitumen synthetic underlayment due to its robustness.
- When it comes to waterproofing, rubberized asphalt underlayment may be more expensive, but it may also be worth it.
Homeowners can achieve a genuine Southwestern style with clay and slate tiles. On the other hand, concrete tile that mimics clay or slate is a more cost-effective option. The tiles are the primary protection against water damage to the roof and interior, but the underlayment is as crucial. Tile underlayment is the roofing material that is fastened to the deck of the roof and that ultimately keeps your roof dry; it is the most critical component of a tile roof.
The State of California has laws regarding underlayment that you need to consider apart from the type of underlayment. For roof slopes between 21/2 units vertical in 12 units horizontal (21-percent slope) and four units vertical in 12 units horizontal (33-percent slope, you are required to install two layers of underlayment.
Underlayment for roofs with a slope of four vertical in twelve horizontal (a 33-percent slope) or greater must consist of at least one layer of underlayment felt applied in a shingle-like fashion. This is done beginning at the eaves and overlapping by at least two inches (51 mm), and fastened only where absolutely necessary.
For areas with high wind speeds (Greater than 110mph or 49m/s) , you are required to secure the underlayment with corrosion-resistant fasteners as per the manufacturer’s specifications. There should be no more than a 36-inch (914-mm) gap between fasteners installed along the overlap.
How Long Does Tile Roof Underlayment Last?
Roofing systems are vulnerable to water damage and eventual collapse if the underlayment fails. If a professional service installs the tile roof underlayment properly, it should survive for many years.
Having a tile roof practically ensures that you will need to replace the underlayment at some point. This is because of the underlayment’s substantially shorter lifespan compared to the tiles. It can be shortened by several things, such as exposure to high or low temperatures, pests, or physical harm from debris.
We can expect at least two decades of use from conventional felt paper and perhaps even longer from some synthetic alternatives. Synthetic fabrics have the highest tear resistance and can withstand severe weather and the weight of roofing tiles.
A tile roof’s underlayment might have a short or long lifespan. This depends on the material it’s manufactured from and the weather it’s subjected to. A lot of them include warranties that might make homeowners feel secure.
Traditional asphalt felt underlayment has a lifespan of 15–25 years. While asphalt-saturated felt, modern synthetic and rubberized underlayments are far more long-lasting and waterproof. These second “type” of underlayments will usually last 25 to 35 years.
With regular maintenance, these underlayments have a 25-year lifespan or longer. Every three to five years, or if damage is suspected, the underlayment should be inspected.
Reasons for Underlayment
Knowing the underlayment’s intended purpose, capabilities, and limitations will help you choose the right kind for your project. Although the underlayment is water-resistant, it does not self-seal, thus water can seep into any nail hole.
If a tile breaks or nail holes are exposed by severe winds, the underlayment prevents water damage by stopping the water from entering the house below. Tiles, over time, become brittle and break that is why tile maintenance is important.
Some other functions are:
- Provisional shelter protection in case of storm damage
- Containment of vapors
- It can withstand some moisture, but it’s not completely waterproof. (Note: some modern underlayments are entirely waterproof)
Many homeowners may be surprised to hear that the underlayment, not the roof tiles, keeps the water from getting into the house. As such, this selection is critical to the future performance of your roof.
There are many tile underlayment options. What’s the best?
Not every roof needs or can afford the most expensive underlayment material. Which underlayment, then, will serve your purposes most effectively? According to the International Association of Certified Home Inspectors, roof underlayment must be eco-friendly (NACHI). Our opinion is, the correct type of tile underlayment should meet your budget and also function well!
Climates in the United States can be broadly classified into four categories (you must match the right type of underlayment to the environment):
- cold and dry
- hot and dry
- cold and humid
- hot and humid
For budget-constrained choices, we would recommend an ASTM 30-pound asphalt-impregnated felt. A trusted brand is Tamko. This is an excellent option for people in California that need the lowest-cost material for their roof.
A middle ranged choice would be a fibreglass mat, SBS (synthetic rubber) at a 40-pound weight. This can increase the lifespan of the underlayment by 50% to 100%. Great brands are TU-43, made by MB Technologies and VulcaSeal G40 Fiberglass (Modified) made by Fontana. This is a great tile underlayment for Californians that are looking for price/quality.
A top premium pick would be Boral Tile Seal (made by Boral). This is the most expensive option but makes up by performance. Boral tile seal leaves no exposed nails because it is self-adhering. Also, it is great for high temperatures and can even be used under metal roofs. This is the best tile underlayment for California’s hot climate!
The Anatomy of a Tile Roof: California
Given the multiple functions a roof must serve, tile roofs have a more complex design. Due to these factors, tile roofs are governed by stricter codes than standard shingle roofs.
A minimum pitch of 2.5:1 is required for clay or concrete tile roofs, whereas a minimum pitch of 4:12 is required for slate roofs, according to the International Residential Code. Some buildings have an ice dam protection membrane installed as an extension of the underlayment to stop icicles from forming on the roof’s edges.
Tile roofs are erected on roof decks (the layer of material that serves as a barrier from outside elements and bears the load of all the other components of the roof). Some varieties of tile roofing have enhanced protection in harsh conditions, such as the southern U.S.
Metal flashing is used to redirect water from roofs, especially when items penetrate the deck. Battens, short strips of material used to support the underlayment and tile fasteners, are set across it.
In the end, the tiles are fastened to these across the roof. Underlayment is laid on top of the roof deck to prevent water damage during and after construction.
For many years and in many climates, a tile roof must support the heavy tiles that make up its surface. Crickets, angled ridges that prevent water from pooling at the chimney’s base, may be necessary on roofs with chimneys.
The Types Tile Underlayments Explained
The roof is inarguably essential, and so are its components. What is the best roof underlayment for tile roofs? When buying underlayment, choose one that will serve you for years, meaning don’t compromise quality due to cost.
Underlayment is the foundation for roofing as it is one of the first protective materials installed. If you want the best for your home, you want to know that every element installed is of the highest quality.
Felt has been a time-proven and even approved option for many residential roofing systems, but does it mean that it is the best for every single case? To answer this question, we must understand the types of options for underlayment and the value provided.
1. Roofing Felt
There are a variety of names for asphalt felt underlayment, such as felt paper, roofing tar paper, felt underlayment, asphalt-soaked felt, and so on. Most roofing projects in the past often employed felt paper since it was readily available, inexpensive, and compatible with different roofs.
Felt underlayment is a universal roofing accessory that begins with a natural (wood cellulose, natural fibers, etc.) or synthetic (polyester or fiberglass) foundation and is subsequently saturated with asphalt to make it waterproof. One major benefit of using felt paper as an underlayment is that it is much more cost-effective than synthetic underlayment.
When water leaks through the roof, asphalt (or bitumen) acts as a barrier, preventing the water from seeping through to the underlayment. However, unlike synthetic underlayment, air and water can more easily move through felt paper due to their higher permeability.
The primary drawback of using felt paper underlayment instead of synthetic underlayment is that it wears out much more quickly. Over time, felt underlayment will deteriorate and become less effective if subjected to extreme heat, direct sunlight, or frequent temperature changes.
Another potential issue with felt underlayment is that it quickly deteriorates in high-temperature settings such as California weather. Since asphalt is an oil-based, semi-solid type of petroleum, it degrades more quickly in high temperatures because the oil in it dries up and cracks.
Felt paper has a very short lifespan compared to other roofing materials. However, most manufacturers guarantee their product for the lifespan of a shingle roof (usually 15 to 20 years). The amount of time spent in direct sunshine should be reduced, as felt underlayment is susceptible to deterioration when subjected to heat and light.
As stated by Construction Pro Tips, some roofing felt can bubble, buckle, and wrinkle in as little as 24 hours of exposure to UV light. You may have to use a slip sheet, a layer of construction paper inserted beneath the roofing material, to further protect the felt underlayment from damage or sticking. This can occur when the felt underlayment comes into touch with metal panels.
The most common weights for felt underlayment are 15 pounds (#15) (for shingle roofs and 30 pounds (#30) for tile and shingle roofs. You may need to buy several rolls of felt paper for a single project, but you can get by with only one roll of synthetic.
Per square foot, these are the estimated weights of the underlayment (100 square feet). Since the weight of one roll of felt underlayment is comparable to that of one roll of a synthetic underlayment, each roll of synthetic underlayment contains at least twice as much material. The contractor will need to transport more felt paper rolls to the job site.
2. Synthetic Underlayment
This alternative underlayment was developed to meet the demand for a synthetic alternative to felt. Synthetic is a vapor-resistant and water-resistant underlayment that is woven from polymer and polypropylene.
A superior alternative to heavy felt, this underlayment is both lightweight and durable. Felt underlayment only lasts for 15-20 years, but synthetic roofing underlayment has a warranty of 25-50 years.
As an example of its many advantages, synthetic underlayment:
- More secure while walking on while laying tiles
- Ideal for use on tile roofing
- extremely lightweight
- Has a high tolerance for prolonged exposure.
- Unlike felt, which can leave unsightly wrinkles on the deck, this material lays flat.
- Waterproof and resistant to vapor transmission
- Holds up even if tiles are ripped off by the wind.
Due to the need for cap nails or staples during installation, the majority of synthetic roofing underlayment is just water-resistant and not waterproof. Synthetic underlayment is more expensive than felt per square foot, which is one of its major drawbacks.
Because it has low permeability, attic and building ventilation are very important when using synthetic underlayment. Having a roof underlayment with a low permeability rating, less water and air can move through it, might be advantageous. However, it can pose problems if the underlayment is not fitted properly.
- For non-adhesive underlayment with a 25-year lifespan, you may expect to pay between $.15 and $.20 per square foot.
- Non-adhesive underlayment with a 50-year lifespan costs $.20 to $.25 per square foot.
- Self-adhesive underlayment with a 50-year lifespan costs between $.55 and $.65 per square foot.
Some roofing companies in California like to use synthetic underlayments for tile in California; however, we don’t recommend them since they are fairly new and haven’t been thoroughly tested by the ultimate decider: time!
3. Rubberized Felt (SBS-modified asphalt underlayment)
Similar to traditional roofing felt rubberized felt has more additives like oil and fiberglass. Rubberized felt is a fiberglass mat is coated with SBS-modified asphalt. The felt type could be considered semi-synthetic. The advantages are:
- Is not organic, doesn’t rot like organic felt
- Lays flat without wrinkles because of the SBS rubberized asphalt
- Economical and is not much more expensive than traditional organic felt
The only drawback to SBS-modified underlayment is the price. It is more expensive than organic felt.
3. Self-Adhering Tile Underlayment
There are many names for self-adhering roofing underlayments. Some call it ice and water shield or peel and stick. Self Adhering tile underlayment is a roofing material with a self-sticking backside and seam that can be “stuck” to the roof by peeling away a plastic film and pressed to the roof deck.
This is the premium option for tile underlayments in California and also the most expensive option. The benefits are:
- Self-sealing capabilities.
- Seams are sealed, and old age edge (lap) curling does not occur as with organic materials.
- Withstands high heat
- 100% waterproof
- Fewer roof fasteners (nails) are required, and none of the required roof fasteners is exposed.
- UV Resistant.
The only downside to self-adhering tile underlayments is they are costly!
How the California weather affects tile roof underlayment
Your roof is one of the primary lines of defence against weather and should be maintained. As you might expect, your roof’s underlayment will deteriorate rapidly if the weather is terrible or if it is exposed directly (ie, a broken tile or missing tile)
Understanding the potential for weather-related roof damage and the subsequent need for repairs or replacement is essential. The elements can shorten the underlayment roof’s lifespan in two ways: gradually, via natural deterioration, and rapidly, through sudden damage from a storm.
It can also be a result of poor installation. A compromised underlayment exposes the roof to damage by the elements.
Strong winds can dislodge and shift your tiles and even lift them, leading to a cascade effect of damage throughout your roof. Having your roof routinely inspected for loose or missing tiles and fixing or replacing them as soon as possible is the best way to safeguard your roof against damage caused by strong winds.
Strong as they are, roofing tiles can break under extreme temperatures. They are prone to cracking, which leaves the roof vulnerable to water damage. Although the cracks themselves are ugly, they could speed up the roof’s demise by exposing the underlayment in certain spots.
Roofing materials determine how long your underlayment will last under these conditions. The heat from the sun accelerates the breakdown of roofing materials. Over time, the roof loses its ability to keep water out because the sun’s UV rays dry off oils on its surface.
This is the reason for the laws concerning underlayment installation in California.
How Long does tile underlayment last?