Insulation, Radiant and Vapor Barriers - Insulation for unheated basement ceiling
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : Insulation for unheated basement ceiling
bc3601
09-27-05, 03:23 PM
I have an old (1860) house with a rough stone foundation and dirt/cement basement floor. The basement is unheated and somewhat damp and I'd like to insulate the ceiling. Your typical recommendation seems to be fiberglass batts paper side up, but I hate working with fiberglass and don't want to create a nesting area for rodents (I removed some really nasty fiberglass with lots of mouse nests previously). Would rigid foam work as both insulation and vapor barrier if fitted tightly between the joists? If so, is polyurethane (thermax) or polystyrene (blue board) better for this application? Thanks!
twelvepole
10-02-05, 08:43 PM
Extruded polystyrene is made by four manufacturers in the United States. Each uses a different: blue, pink, green and yellow. All four are basically the same. It's resistant to water penetration and is often used to insulate foundations below grade.
Beadboard or expanded polystyrene insulation is very similar to what is used to manufacturer styrofoam coffee cups. It consists of little beads that are fused together. R-value varies with densitiy. It is water resistant.
How effective the rigid panels work as a vapor retarder will depend on how well they are installed, as vapor can find its way around the edges of the panels.
Beadboard or expanded polystyrene insulation is very similar to what is used to manufacturer styrofoam coffee cups. It consists of little beads that are fused together. R-value varies with densitiy. It is water resistant.
How effective the rigid panels work as a vapor retarder will depend on how well they are installed, as vapor can find its way around the edges of the panels.
wolfclan
10-04-05, 10:44 AM
sadly it isn't rodent proof either... :(
Cerestes
10-04-05, 10:59 AM
No, but it would be alot easier to spot a nest, clean it out, and add in a replacement piece.
It seems like a technically sound idea. Cut to the boards to fit joist bays, possibly caulking around the edges of the top board to stop air infiltration.
But my god. Doing it just to avoid working with fibreglass? It seems like an incredible amount of work, mess (what, a table saw to cut the styrofoam to fit 16" oc studs?), just to avoid a possible problem with rodents later down the road.
It seems like a technically sound idea. Cut to the boards to fit joist bays, possibly caulking around the edges of the top board to stop air infiltration.
But my god. Doing it just to avoid working with fibreglass? It seems like an incredible amount of work, mess (what, a table saw to cut the styrofoam to fit 16" oc studs?), just to avoid a possible problem with rodents later down the road.