Pipe Thread Sealants: Teflon Tape and Thread Compound

Pipe thread sealants are not an interesting subject. But if you’re reading this, you’ve realized how important they are. But I’m not going to write an in depth and comprehensive plumbing blog about this dry subject. This isn’t for the apprentice plumber to learn their trade. This article is for the average homeowner just trying to make a plumbing repair. So look further on the internet if you want to win an argument or double check what your plumber recently did. I’m going to explain what you need to know and not all that you can know about thread sealants.

What are thread sealants?

Thread sealants are a product to be applied to a manufacturers thread to assure a tight seal. In plumbing you’ll normally find this on water, drain or gas pipe threads. And before we talk about what they do let’s figure out what basic forms they take.

Teflon tape

pipe thread seal tape
Pipe thread tape sealant

Teflon tape isn’t the correct name for this particular type of thread sealant. But it’s probably the term you’re most familiar with. Thread seal tape is the correct term. Teflon is a brand name. And plumbers have a million terms for just about everything. Thread seal tape normally comes in the form of a 1/2 inch white tape that’s wrapped around a thread multiple times. My preferred brand of thread seal tape is manufactured by Oatey. The type you use matters. But it isn’t used for all threads or connections.

Thread compound

pipe thread compound
Pipe thread compound

Thread compound is the paste version of thread seal tape. It’s very easy to use but can be pretty messy. And it’s usually overused. It was originally yellow. Ol’ yella number 5 was the term we used. But the white teflon based thread compound is what you want. My preferred thread compound is Tplus2 manufactured by Rectorseal.

What do thread sealants do?

Thread sealants aren’t a fix all. And they don’t do as much as you might think. They serve only a few purposes. And can actually create problems if not used properly. Thread sealants do the following:

  • Lubricate threaded joints to allow for a tighter fit.
  • Partially seal any voids.
  • Prevents thread joints from rusting and allows for an easier removal of threaded fittings.

As you can see, they do a few things. And not always all for each joint. Sometimes you just need a threaded fitting to come apart more easily in the future. It doesn’t necessarily have to be leak proof. This is common on the thread joint between a water heater relief valve and it’s threaded drain pipe.

Where to use thread seal tape

Where to use thread seal tape is very much a personal decision. Many plumbers will argue this point. But after being taught in the plumbers union and serving as a residential plumbing technician for an additional 20 years, I’ll tell you my opinion.

As a rule I use thread sealant tape on all threaded fittings that must be air or water tight that do not have an alternative seal on them already. That means that if there’s a rubber o-ring or washer of any sort, I won’t use thread seal tape. It could get in the way of a proper seal. Flare joints are another spot that I won’t put thread seal tape. That includes flared copper water pipe and tubular drain pipes such as p-traps and tailpiece connections. But I never use thread seal tape on gas pipe of any kind…ever. I don’t even use the special tape for gas pipe. I only use thread compound on gas pipe.

Where to use thread compound

You can use thread seal tape and thread compound interchangeably. The only exception to this rule is gas pipe and flare joints. Gas pipe should be joined with thread compound only. Flare joints should be joined with thread compound only. If I were a homeowner and had limited resources I’d just purchase liquid thread compound. You can use it anywhere a do it yourselfer would work.

How to install thread sealants

As I’ve said before, you can use both thread seal tape and thread compound pretty much interchangeably. But I was taught to never take any chances on a leak if you don’t have to. And you never have to. So I follow the guidelines already discussed. But when I use them I do it in a very specific and consistent way.

How to install thread seal tape

When wrapping threads with thread seal tape you begin at the second or third thread. Never the first. This helps with starting a thread connection without cross threading it. You wrap your threads clockwise three times. Clockwise so that the tape won’t unwrap while screwing things together. Three times because any more is really a waste.

How to install thread compound

Install pipe thread compound only on the first and second threads of the male thread only. This will prevent it from getting inside the pipe. If you wipe it into the female connection the compound will be forced into the pipe. If you’re working with gas pipe the compound could get into a gas control valve and foul them badly.

And don’t waste thread compound. Only spread a little bit onto the first and second threads. Any more than that is wasted. It’ll just make a mess.

How this plumber was taught to install thread sealants

When I use thread compound I follow the instructions above. When I use thread sealant tape I use both; always. I wrap the threads three times starting at the second thread. I then wipe thread compound on the first and second thread only. I do this every time; not most of the time. And I don’t get leaks.

When to call a professional

Sometimes a thread will leak no matter what you do. And sometimes you can damage a plumbing appliance or fixture if you improperly apply thread sealants. If it just won’t seal correctly or if you’re dealing with gas pipe just call us. Advocate Master Plumbing will ensure you’ll always speak to a master plumber on the phone. And that same master plumber will come to your home and resolve your plumbing issues. We don’t train our plumbers to sell. We train them to serve our customers.

Leaking Ceiling

Advocate Master Plumbing has been helping lees summit plumbing customers with leaking ceiling diagnostics for years. A ceiling water leak can be scary. Water streaming from a light fixture or water stains on your ceiling can just make you see dollar signs. Finding the cause of the leak doesn’t have to cost you anything. Let us show you how our plumbers approach ceiling leak detection.

A plumbers diagnostic approach to a leaking ceiling

When I get a plumbing service call for a leaking ceiling I already know what it might be. There are a few very common reasons for leaks. And while taking the call I always have some questions for the customer. Then when I arrive I let them vent a bit and tell me their story. Even though this is routine for me, it’s a major life event for them. Once they’re more relaxed I can begin the leak detection process. It always begin with further questions.

Where is your ceiling leaking?

This is an obvious question. And usually I’m told during my customers retelling of the events. A brownish water mark on the ceiling is a small leak. But a larger leak will include a long straight brownish line. This is pooled water finding a seam in the drywall.

Is there a bathroom above the leaking ceiling?

It’s uncommon for pipes to leak. It’s usually a plumbing connection to the pipes. So I always ask if there’s a bathroom above the leak. A leaking tub or shower is most common. A leaking toilet is also very common. Then I try to go deeper with my questioning.

Leaking tub

leaking bathtub waste and overflow drain assembly
tub waste & overflow

If I suspect a leaking tub I’ll first look at the caulking and grout around the tub. Caulking and grout are both temporary. They both need occasional maintenance or replacement. Shrinking caulk can actually channel water into the wall. And grout voids allow water to saturate backer board/drywall. The tile depends on this for structural integrity.

I’ll also check for a cracked tub or loose tub drain connection. And lastly, I’ll check for a loose overflow assembly or shower valve trim. This is usually easily repaired by either tightening a screw or sealing with silicone caulk. I’ll always use clear 100% silicone caulk. Clear because it’s easier to work with.

Leaking shower

Leaking shower, shower drain leak
Plastic shower drain

A shower leak will be checked the same as the tub leak. But I’ll also check the special shower drain. A cracked shower drain on the shower base is very common. The shower bases can sometimes flex when walked on. If the drains are made of plastic, the flange portion of the shower drain can crack or loosen. This will require a replacement. My preferred shower drain replacement is manufactured by Sioux Chief and is brass. This is a permanent repair.

Leaking toilet

Leaking toilet wax ring
Leaking toilet wax ring

A toilet leak can be caused from a multitude of things. To find the cause of a leaking toilet when water is on the floor you always look up. Follow the leak upward until there is no leak. Then look down. For more about this you can check the DIY toilet repair page.

A leaking ceiling that’s caused by a toilet will sometimes not show any water on the floor. If it’s a leaking toilet wax ring then that just requires a wax ring replacement. But if the toilet flange is too far below the floor you may need a flange extension. The wax isn’t meant to seal a large gap. It will sag over only a few years. But sometimes leaking toilet wax ring is due to a loose toilet caused by loose bolts or a cracked toilet flange.

Have you used the garden hose recently?

leaking spigot, burst hydrant
Frozen & burst sillcock

A burst sillcock can occur when a garden hose is left attached during cold weather. An older sillcock that isn’t frost free needs to be shut off inside the house and drained. But normally you’ll have a frost free hydrant style sillcock. They are specifically designed to drain themselves. This keeps the water pipe far from cold air. But they can’t drain if you leave the hose on. Trapped water freezes. As it freezes it builds pressure. Enough pressure to crack the brass sillcock housing. But a water leak will only occur when the sillcock is turned on. And it’ll leak inside while you’re outside wondering where all your water pressure went.

Have you been using the kitchen sink?

We all use the kitchen sink daily. But sometimes a large amount of water at the ceiling and wall connection can mean a cracked kitchen drain stack offset. The kitchen drain stack is a pipe that runs from under your sink, inside the wall and down to the basement. The kitchen sink is often on an exterior wall. But the wall is sitting on a concrete foundation. So the drain needs to offset about 6 inches to get around the top of the concrete wall. If you have black ABS plastic drain pipes it’s very possible this drain pipe has cracked. And the offsets are a weak point. This is especially true when there’s been settling in a house.

Frozen and burst water pipes

This isn’t a question. During cold weather a frozen pipe can burst and leak in a garage ceiling or along an exterior wall. Shower drains and tub drains can freeze and leak. Cold weather highlights the weaknesses in your home insulation. For more information about this you can go to How to Deal with Frozen Pipes to prevent this.

Leaking plumbing appliances

Normally a water heater will be on the lowest level of the home. This is also true of an hvac system or washing machine. But sometimes they aren’t. So check behind and under the washing machine. Test the drain for intermittent drain clogs. Check the water heater for leaks. They can have thermal expansion that will cause the relief valve to only leak occasionally. And an air conditioner condensate drain can back up. A condensate pan can clog creating water streaks down the side of the a/c. A furnace humidifier drain hose can clog or leak as well.

Some uncommon causes of leaking ceilings

When all else fails you look to the uncommon things. A roof offset near the ceiling leak can mean some roof flashing needs to be sealed. Leaking from a bathroom can be from an improperly sealed shower door or just splashing in the tub. A leak in the middle of the house with no plumbing fixtures around it can mean someone dropped some water on the floor or a water pipe leak or a leaking drain or vent pipe connection. I’ve even seen nails or screws that take years to rust away after penetrating a water or drain pipe.

Who fixes leaking ceilings

Finding the cause of a leaking ceiling is where a good plumber earns his pay. It can be frustrating trying to find the cause. And we don’t want to just start cutting holes in ceilings without being sure. But sometimes it’s all we can do. So in short, don’t hire a handyman for this. And don’t try to DIY this. A ceiling leak should be left to the professionals. Call your local Lees Summit plumber near you. Advocate Master Plumbing will perform a leak detection in a methodical and professional manner while minimizing damage to your home.