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TheClumsyCarpenter 03-14-2010 06:02 PM

Ever scared to seal the wall up?
Finally finished replacing all of the fixtures in the Master Bathroom today. It's been quite a process, because getting into it I had no idea fixtures were so brand specific. So the wife bought what she wanted, and then turns out I had to remove the access panel under the standalone tub, cut the copper supply lines, put in all new fixtures and repipe.

It was also a giant pain to replace the tub drain, as it was so tight just using a normal pair of pliers to thread out the drain resulted in breaking 3 of the 4 arms on the cross.

Long story short, it was a pain. Today I finally was able to get the drain assembly back in the tub, and had it leak on me twice. After loading it up with some plumber's putty and really cranking it down, I was unable to get the tub to leak again...however.

Don't you just get worried about what's going on behind closed walls? I filled the tub to just under the overflow opening to create the highest amount of pressure the seal should see, and opened up the drain and couldn't get it to leak. Even did it a second time to make sure...and no leaks.

But I'm worried.

What type of project have you done, where you were a little concerned about what's going on behind the wall after you close it back up?

Nestor_Kelebay 03-14-2010 07:08 PM


In my case, I renovated 21 bathrooms in an apartment block. But, unlike houses where you might have access to the plumbing from the opposite side of the wall, apartment blocks have "fire partitions", or concrete block walls around each vertical column of apartments. That way, if there's a fire in one apartment, it won't spread laterally, only vertically. So, in all 21 bathrooms, I had a load bearing concrete block wall behind the T&S faucet and a ceramic tiled wall in front of it. If I ever had to go back in to replace a leak, I'd have had to tear down the brand new ceramic tiling.

So, I religiously pressure tested my plumbing before I closed anything up. Good thing, too. None of my solder joints ever leaked, but I did have a defective brass shower elbow that had a pinhole leak right through the brass.

Lots of plumbers use silicone caulk instead of plumber's putty on drains nowadays. I think in an application where you won't have easy access to the leak, next time use silicone caulk instead of plumber's putty. The hassle of removing silicone caulk is small compared to the hassle of opening up the wall again to access the drain piping. However, if the instructions told you to use plumber's putty, it should work OK with plumber's putty, too. Still, if it wuz me, and if it wuz in a critical application like this seems to be, I'd have prolly used silicone caulk instead of plumber's putty.

Is it not possible to just put that access panel you mentioned back up until you have confidence in that drain piping? Maybe repair the hole in the ceiling permanently once you're more confident than you are right now.

It might also be a good idea to put some Diazinon (or other insecticide) powder in the ceiling or wall immediately before closing up the wall or ceiling. As long as Diazinon powder remains dry, it'll stay effective for many years. It's only when it gets wet or is subject to large temperature changes that it'll deteriorate rapidly. Diazinon is an effective pesticide. Since condensation will form on and drip off your cold water supply piping during humid weather, it's a good idea in my books to have some pesticide powder in the walls or on the floor under the cold water pipe to kill any bugs attracted to the water that drips off it.

If you can't find an effective pesticide in powdered form, or you want to remain "green", then use Borax from the laundry aisle of your local supermarket. Borax and borates have very little toxicity to mammals; we and our pets can just about eat the stuff. However, borates are highly lethal to molds and fungii, including the kind that causes wood rot. If nothing else, putting some Borax on any wood up there will help prevent it from rotting or having mold grow on it if it does get wet. Borax (and borates in general) are highly soluble in water. So, lots of water leaking is likely to just wash the Borax away. But, a light drip (if there is one) that would just get the wood wet enough to allow the Borax to dissolve and penetrate throughout the wet wood would help protect it from wood rot. Never apply Borax to your lawn or flower beds to kill bugs tho, cuz it'll kill both grass and your flowers. It's surprising that Borax and borates can be so well tolerated by mammals, and yet be so toxic to fungii and other kinds of living things.

Borax is not the same thing as borates, but my understanding is that it's the Boron in both that's lethal to molds and fungii, so Borax might not be as effective as borates, but it should help regardless.

If you want to know more about using borates to prevent wood rot, just Google "Impel rods" or "Cobra rods" or "Boracol" liquid. Borax is apparantly also quite an effective pesticide against ants, as well.

Wuzzat? 03-14-2010 08:26 PM

I'd think people stepping in and out and day/night temp. changes would be more likely than water pressure to induce a leak.

Moisture meters in the hardware store are $30; I guess you could periodically check the ceiling of the next floor down.
But, I don't know how many consecutive months of "no moisture" you would need to safely declare it watertight.

Or you could put in a $16 water detect box on the subfloor surface in areas likely to collect water. It needs to be accessible, of course.

I guess I would leave the area open for a while.
With skylights, I left the lightwell drywall off for six months before a driving rain finally revealed a leak. Fixed the leak, installed the sheets and that was in 1994. No later problems.

TheClumsyCarpenter 03-15-2010 07:26 AM

Thanks for the info.

The instructions specifically said to use plumber's putty, but next time I will look into using the silicone caulk.

I suppose I could leave the panel open for a while, but I guess I'll never know when I would be confident that "one more time" is enough. That's the biggest problem with just learning how to do this stuff and trying to become more of a repairman around the house...doing it the first time is always iffy.

Redwood 03-15-2010 08:28 AM

Whoa there on using Silicone RTV Caulk!
Silicone will make it nearly impossible to ever remove the drain again.

The actual sealing that prevents leaks is accomplished by the rubber washer that goes between the tub and the drain shoe. Leakage at the putty connection would only allow the tub to drain bypassing the stopper and would not leak.

Too much plumbers putty may push the rubber washer out of place or, prevent you from tightening the connection enough. Using a Dumbbell Wrench will enable you to tighten the drain enough without breaking the crossbars out.

handyguys 03-15-2010 09:19 AM

Redwood, you beat me to it. +1 for redwood.

handyguys 03-15-2010 09:50 AM

oh, and yeah. I always worry about forgetting something. I test what I can and follow best practices when doing an install.

Drywall is cheap so if you have to open up something again its not a huge deal I guess.

I was doing an addition on my house and couldn't figure out where my favorite tape measure went. Doh, i put it down on some blocking in a wall and drywalled over of it. I bought a new tape measure as opposed to a new sheet of drywall.

Redwood 03-15-2010 11:36 AM

Here we are lucky with most backing walls for the tub in an adjoining closet.
They seldom get completely repaired and often remain as an easy to open access panel. Out of sight out of mind and oh so easy to get into.

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