– Waferboard: this type of material is suitable for both residential and commercial roofs. It has an asphalt coating and is usually used in climates that do not get a lot of rainfall – Plywood: this type of material is less expensive than other underlayments, but requires a lot more work. You will also need to add the additional waterproof sealant on your own – Foam: foam is often used with commercial buildings because it is easy to install and will last up to 50 years.