What's the Difference: Joint Sealing with Teflon Tape and Pipe Dopecomments (7) March 5th, 2009 in Blogs
by Rob Yagid
The success of any plumbing project hinges largely on the quality of its joints. Threaded connections between metal or plastic parts can be particularly problematic if not sealed properly. Teflon tape and pipe dope are used to fill voids between male and female threads to make joints leakproof and to prevent metal parts from rusting together. People often use pipe dope on top of Teflon tape, but some manufacturers say there is no benefit to that usage and that Teflon tape and pipe dope perform the same whether they're used individually or together.
Pipe dope is easier to apply
Pipe dope, technically known as pipe-joint compound, is available in containers as small as 1 fl. oz. and as large as 32 fl. oz. To apply pipe dope to the male end of a threaded pipe or fitting, swab the threads with the supplied brush full of compound. Although using pipe dope can be a bit messier than sealing with Teflon tape, it's faster. Similar to Teflon tape, pipe dope comes in versions designed for water lines and for gas lines. Read packages carefully because all dope cannot be used on plastics.
Approximate cost: $3 per 8-oz. can
|Dope stays gooey. Pipe dope never hardens, so it will never become brittle and flake out of a joint.|
Teflon tape is less messy
Teflon tape, which is available in 1⁄2-in. to 1-in. widths, comes in high- and low-density versions. While Teflon tape is less messy than pipe dope, it can be more difficult to apply properly. If wrapped wrong (in a counterclockwise direction), the tape can ball up as components are tightened, ruining the seal. Many pros complain about the quality of low-density tape, which is less expensive. More low-density tape is required to seal a joint properly because it compresses more than high-density tape. Low-density tape also tends to shred easily. A strand of tape that finds its way into a plumbing line can cause problems.
Approximate cost: $1 per roll
|Tape is less messy, but there's a caveat: If wrapped wrong (in a counterclockwise direction), the tape can ball up as components are tightened, ruining the seal.||Teflon tape for residential plumbing is color coded. High-density pink tape is used on water lines; yellow tape is designed for gas-line use. White tape (often low density) is used on water lines.|
posted in: Blogs, water and moisture control, plumbing
Learn techniques for protecting the window opening with an angled sill and flashing tapes read more
About this Blog
Fine Homebuilding is the largest and most trusted residential construction magazine around. Every issue has the information you need to build better, all written by the “guys who swing the hammers.” In Fine Homebuilding, these experienced pros show you what they’ve learned, and on these pages, you can read the current and past issues.