My husband and I recently purchased a home built in the 1940s. All interior and exterior walls are constructed of wood ship-lap which have multiple layers of wallpaper and paint. We started stripping the wall paper of the ship-lap in order to install gypsum wallboard. While removing the multiple layers of wallpaper we came across an underlayment which was applied to the wood ship-lap and beneath the wall paper. The underlayment is a grey, felt paper like material. We are wondering if such a material contains asbestos. In all the internet research we have done we can not find the exact product which was used as an underlayment. I am curious if someone has run into a similar product or has knowledge of such a product and knows whether it contains asbestos.