Is additional insulation necessary when installing PVC ceilings?
Rentia
| Posted in GBA Pro Help on
We are currently building a new home. I’ve read that PVC ceilings have excellent insulation properties. If we install these, will it be sufficient or is additiona insulation in the roof necessary?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Rentia,
I have never heard of a PVC ceiling. Are you sure that the product you are looking at is really made of PVC?
Where do you live?
PVC is vapor-impermeable and would make a poor choice for an interior finish material.
I have never heard of PVC insulation, so I would have to assume that a PVC ceiling material would have a very low R-value.
Unless you live in a very mild climate (for example, parts of Hawaii), your ceiling or roof needs insulation. Minimum insulation levels are usually dictated by local building codes. In most of the U.S., these minimum insulation levels range from R-30 to R-49.
I've installed Azek (cellular PVC) beadboard on ceilings. I don't think it adds much insulation, probably R-1 or 2 at best. This was on the first floor ceiling of a two-story house, so the fact that it's impermeable doesn't matter. Although if you are using individual board there is enough air flow that I don't think it would matter even if there was insulation on the other side.
Side note, it does not like recessed lights--they get hot and make the PVC sag. And PVC is not an environmentally friendly material, so just use wood if you want the board look.
We are living in South Africa and our building codes doesn't specify minimum insulation. It is very difficult and expensive to build green here. I'm doing research on every single material that is used in our new home and it is very difficult to get reliable information. You can have a look at http://www.astonishingceilings.yolasite.com. The information that I've got on PVC ceilings from this and other websites is that it is a very good and eco friendly product, I'm just not sure about the insulation properties.
Rentia,
South Africa is a big country, but the climate in many areas of South Africa resembles the climate in some parts of California. Even in California, building codes require ceiling or roof insulation.
The product you linked to appears to be a finish material for ceilings, not an insulation product. Whatever finish material you choose for your ceiling, you still need to install insulation (fiberglass batts, blown-in fiberglass, cellulose, spray foam insulation, or rigid foam insulation).
Very few green builders would agree with the statement that PVC is environmentally friendly. The only groups claiming that PVC is environmentally friendly are manufacturers and distributors of PVC products.