Roofing felt is similar to fleece made from polyester or fiberglass and then soaked in waterproofing agent. 15 pound and 30 pound refers to the thickness of the felt, with the numbers indicating the weight of 100 square feet of this paper back when they were originally developed.
What does 30lb felt mean?
In the past, the felt number designation was correlated to the weight of the felt (i.e., a 15# felt weighed 15 pounds/100 square feet). … By shifting the pound symbol, 15# felt became #15 felt, which may actually weigh 7.5 to 12.5 pounds per square; #30 felt can weigh between 16 and 27 pounds per square.
When should I use 30lb felt?
Weight Matters The best weight for roofing felt is the 30-pound product, because it provides thicker and stronger footing for roofers that does not tear out, especially on steep roofs where footing is critical.
What is the difference between 15 pound roofing felt and 30 pound felt?
While #15 is a good option for most roofing jobs, #30 provides more protection and performance for steep roofs and flat roofs. … But if your roof has a steep pitch, #30 is a better option because it is thicker and tears less during installation. With #30 you get a thicker layer of underlayment and protection.
Why do they call it 30 pound felt paper?
Historically, roofing felt paper was named for weight. 15-lb felt paper weighed 15 pounds per 100 sq. ft. (one roofing square) and 30-lb felt paper weighed 30 pounds per square.
Is 30 pound felt waterproof?
Is Roofing Felt Waterproof? Roofing Felt is the support material that is required to develop roll roofing and roof shingles. Being used as the waterproof coverings in commercial as well as residential roofs for decades, these membranes comprise two layers, signifying it is waterproof.
What felt is best for roofing?
- Our Pick. Chesterfelt Green Mineral Premium Grade Shed Felt.
- Best Alternative. IKO Shed Felt.
- Felt Shingles Roofing Tiles.
- Ashbrook Roofing Super Grade Polyester Reinforced Shed.
- Rose Roofing Green Heavy Duty Shed Roofing Felt.
Is synthetic underlayment better than felt?
For enhanced water-resistance and protection from the elements, many roofers are choosing to go the route of synthetic roofing underlayment. … This type of underlayment is typically moisture-resistant, and when it’s installed correctly, it offers better protection from the weather compared to felt.
Does roofing felt keep water out?
The felt can get wet. However, due to its water repellent properties, it acts more as a shield than a sponge. The felt collects and then repels the water, allowing the roof to breathe. Felt will often get wet with a Cedar shake roof since this type of roof is designed to soak up then shed water.
What is the best underlayment for roof shingles?
1. Asphalt-saturated Felt. This used to be the most popular choice for roof underlayment until it was replaced by synthetics. It’s usually known as tar paper or felt paper and it can be made from various mixtures of asphalt, polyester, cellulose, or bitumen.
How many rolls of felt make a square?
Rolls of felt coverage for roofs is sold in rolls that are one square each. One roofing square equals to 100 square feet. Always double check with the roofing calculator to make sure that you have enough felt to cover the entire area of the roof.
What are the different types of roofing felt?
- AirTight – These consist of a three or four layer vapour permeable membrane. …
- Air Permeable –These are generally made up of three layers, to create a vapour and air permeable membrane.
What is the difference between tar paper and roofing felt?
Tar paper is a heavy-duty paper used in construction. … Tar paper is distinguished from roofing felt, which is impregnated with asphalt instead of tar, but these two products are used the same way, and their names are sometimes used informally as synonyms. Tar paper has been in use for centuries.
Can you double felt a roof?
So it is possible to have 2 layers of felt in General. For instance, an alternative to 30# felt is to put two layers of 15# felt, or often 2 layers are recommended on a 2/12 pitch roof. In the “good Old Days” it was often doubled up to help resist ice dams (now delt with by Ice and water Shield).
Do you need underlay for roof shingles?
No matter what type of asphalt shingle you are using, whether traditional or more robust styles (such as under premium designer, architectural and performance shingles) it is recommended to use a underlayment.
Is tar paper necessary under shingles?
Answer: Roofing felt is a layer of tar paper installed beneath the shingles to provide a backup waterproof membrane in case of leakage. … But don’t let the lack of underpayment become a major issue for you, because it is simply not required for a second layer of composition shingles.
How long can 30 lb felt be exposed?
How long can 30-lb felt underlayment be exposed to sun before new 30-lb felt underlayment is required? Can anyone provide reference material? Thanks for your help. If you are referring to asphalt-saturated felt about 2-1/2 to 3 months.
How long can felt roof underlayment be exposed?
Most synthetic underlayments can be left exposed for six months and some for 12 months. The woolly, tan-colored Opus Roof Blanket, though, is approved for 30 months of UV exposure. underlayment for several good reasons. While the price of asphalt felt fluctuates somewhat, it’s still the least expensive option.
What is the best felt for flat roof?
EPDM Membranes Quite possibly the best flat roofing membrane, EPDM is a relatively low-cost flat roof material that offers a number of significant advantages. Clean, straightforward installation, incredible strength, a long lifespan, and a smart finish combine to make EPDM membranes a difficult one to beat.
Do you need underlay for torch-on felt?
The torch-on felt solution relies on a three-layer system, which will require two levels of underlay underneath the cap sheet.
How many layers of felt should a flat roof have?
Felting a flat roof requires three layers of felt, so triple the square footage in order to calculate how much felt you require.
Is synthetic felt worth it?
With that in mind, synthetic underlayment is more durable than felt underlayment. Felt underlayment is much more prone to rip from high winds and during the installation process. Synthetic underlayment also holds nails better and repels water instead of absorbing it.
Can you shingle over wet synthetic felt?
Other common shortcuts your roofer should avoid: Do not shingle over wet or damp roof sheathing or damp felt paper. The trapped moisture cannot evaporate when the sun heats the shingle. If you plan to stay in the home for the next 10 years, do not shingle over older shingles.
How thick is synthetic roof underlayment?
It is available in two thicknesses, 15 pound and 30 pound. Those numbers are a reference to how much 100-square feet of the paper used to weigh back in the early days of its use. The actual weight-per-square foot these days is actually less than the label says, but the 15 pound. and 30 pound.
Can you repair roof felt?
For larger sections of felt roof, patching is the most cost-effective and time-saving method. When patching, the first step to repairing a felt roof is to cut away the section which has become damaged. We recommend doing this by first scoring with a specialist Stanley knife and then cutting through.
Can you roof over wet plywood?
A: It is never a good idea to install a roof over wet plywood or any type of roof sheathing. Trapped water will boil when the sun heats the roof and the shingles will then have small pits where the steam finally escapes.
What should I put down before shingles?
Before laying down shingles, you need to protect the roof with sheathing. Roll out a single layer of roofing felt or tar paper, which serves as a moisture barrier. Begin this layer at the bottom of the roof and add it in horizontal rows, with a slight overlap to prevent leaks.
Is Tiger Paw underlayment better than felt?
Tiger Paw Synthetic underlayment is not only superior for its application on the roof, but its much easier on our installers as well. … Safer for Installers: It’s specially designed surface helps provide excellent walkability for installers versus conventional felts, or typical synthetic underlayment’s.
What is the minimum underlayment for asphalt shingles?
for asphalt shingles, NRCA recommends a single layer of no. 15 asphalt-saturated underlayment be used with roofs having slopes of 4:12 (18 degrees) or greater. for roof slopes between 3:12 (14 degrees) to 4:12 (18 degrees), NRCA recommends a minimum of two layers of no. 15 underlayment.
How many square feet does a roll of 15 lb felt cover?
Roll Self-Adhered Roofing Underlayment (225 sq. ft.)
How do you measure roofing felt?
Measure the length and width of the structure at ground level in feet. Multiply the measurements to determine the total area covered by the roof. If you have an irregularly shaped building, break the structure into several rectangles and measure each separately.
How many rolls of roofing felt Do I Need?
How Many Rolls of Felt Will You Need. Roofing felt is sold by the roll. The average roll of 15-pound roofing felt covers about 400 ft2, or 4 squares, while the average roll of 30-pound roofing felt covers about 200 ft2, or 2 squares. Rolls of felt are 36″ wide x 144′ long for 15# and 72′ long for 30#.
Are there different roofing felt grades?
There are three types of roofing felt to consider for a roofing project; torch-on felt, self-adhesive felt and shed felt.
What is the thickest roofing felt?
Roofing Paper Thickness The most commonly used felts are #15 and #30, with weights of 8 and 20 pounds per 100 square feet, respectively. The most commonly used is #15, which comes in rolls 3 feet wide, is 144-feet long and covers approximately four squares per roll, or approximately 400 feet of roof.
Is synthetic felt better than tar paper?
Synthetic underlayment is much more tear-resistant when exposed to high winds and foot traffic than asphalt felt underlayment. Since synthetics do not absorb moisture, they are resistant to fungal growth and are wrinkle-free.
Does roofing felt seal around nails?
2 – Modern roofing felts have an unusual property in sealing around the clout nails when penetrated and if you aren’t sure then put a small dob of roofing mastic on the nail before fixing it. This sometimes gets messy so keep a rag handy to wipe the hammer head occasionally.
What do roofers use instead of tar?
Synthetic underlayment was developed as a felt replacement. By weaving together polypropylene and polymer, a water-resistant and vapor resistant underlayment was created. This new underlayment is lighter and stronger than its predecessor. Contact Fowler Homes for roofing services in Canton and nearby areas today!
Is it OK to leave Old felt on roof?
Shingle Manufacturers clearly state that new shingle must be installed over a proper nailing surface but without removing all the old felt a proper decking inspection cannot occur! Leaving the old felt on is a dangerous shortcut that can have serious implications to your roof, and possibly void your new roof shingle …
Can you lay new roof felt on old?
Many people ask if you can felt over old felt. … We would advise stripping the roof so that you can inspect and repair the roof timber before then laying down a new layer of roofing felt.
Can you put roof shingles over felt?
Shingles can be laid over existing roofing felt, but the surface must be both flat and in good condition to avoid imperfections in your finished roof. If in doubt, we recommend you strip it back to the oriented strand board (OSB).