A method for making a Si-containing material comprises transporting a pyrolyzed Si-precursor to a substrate and polymerizing the pyrolyzed Si-precursor on the substrate to form a Si-containing film. Polymerization of the pyrolyzed Si-precursor may be carried out in the presence of a porogen to thereby form a porogen-containing Si-containing film. The porogen may be removed from the porogen-containing Si-containing film to thereby form a porous Si-containing film. Preferred porous Si-containing films have low dielectric constants and thus are suitable for various low-k applications such as in microelectronics and microelectromechanical systems.