Steel Roofing Underlayment Options

When applying steel roofing, it is important to install the right type of underlayment to meet your needs. The wrong type will not work properly and will leave you with expensive repairs in the future. By taking the extra few steps now, you will have the security of a good roof for many years. The right underlayment will act as a protective barrier between the deck of your roof and the materials you install on top of it. It will help make sure that the roof is installed evenly and without being distorted.

Felt Underlayments

The most common material for underlayment is roofing felt. If your metal roof is going to be placed right against the roofing felt, you would need to have a sheet of red rosin paper to keep the underlayment from sticking to the metal.

The felt is composed of petro-chemically soaked materials, both organic and non-organic. It is pressed together with coal, pitch or asphalt. 

Using felt is an old and reliable way to underlay your roof and it will probably be the most cost effective in your area, though many newer underlayments will be easier to install and may have better results.

Polymer-Based or Synthetic Underlayments

With modern day technology, polymer-based or synthetic underlayments have been created that withstand time and weather better than the old felting system. Though slightly different materials are used to create the underlayment, polypropylene and polymer are the two most popular ingredients.

Many polymer-based underlayments are designed to last as long as the metal roof you install. This is good and convenient, as you would not want to pick up your roof just to fix the underlay. Spending the extra money on these types of underlayments will prevent you from expensive repairs or new installments later.

Polymer-based undelayments are generally 15 to 25 times stronger than those made from felt material, and they are water-resistant. It is also easier to install.

UV Resistant

If you are buying polymer underlayment, make sure to buy a product that is UV-resistant. This feature will protect your underlayment from becoming weakened by the sun, and it will also keep your home cool in the summer.


Some versions of polymer-based underlayments come with a self-sealing membrane that will close over nails once secured to the roof. This benefit will help your roof withstand leaks from rain and other weather conditions.  

Steep Ridges

If your roof is built with steep ridges, consider spending a little extra on an underlayment that will have a no-slip surface. This will make it easier and safer when you or a crew is installing the underlayment, preventing injury from slipping or falling.

The material of your underlayments is an important thing to consider when you are installing a new roof, as they will only last a certain amount of time. Choose one that withstand weather and time.