Getting a Oatey 42099 Drain Sealed Right the First Time
The Oatey 42099 is a 4-inch brass shower drain body designed for threaded connection toSchedule 40 or 80 PVC waste piping. It comes with a raised flange option and works with both cement and solvent-weld joints depending on the subfloor setup. Most people buying this just want it to stop leaking under the tile and they've inherited instructions that read like a riddle. I'll walk through how it actually goes together on a typical remodel where the subfloor isn't perfectly flat. Start by dry-fitting everything before you commit anything to glue. I know that sounds obvious, but the biggest reason these drains leak in year two is that the installer cements the tailpiece at a slightly off angle and then forces the flange level by twisting the drain body into the pipe. That creates stress in the joint and the whole assembly shifts under tile load. My approach is to set the waste pipe so the top of the pipe sits roughly 3/8 inch below the finished subfloor height, not flush. The 42099 is designed to accept a layer of mortar or setting material underneath the flange, and that gap matters for leveling. Cement the bottom joint first using Oatey Heavy Body PVC cement or an equivalent medium bodied formula. A medium bodied cement is important here because you need a few seconds of adjustment time before it sets. Apply primer to the pipe and fitting if the cement isn't a self-priming formula, which most heavy bodied cements aren't. Push the tailpiece into the drain body with a firm quarter turn. Hold it for about ten seconds. Then use a level on the top rim of the drain to confirm the flange is plumb before the cement takes a grip. If it's off, you can nudge it for maybe thirty seconds before it becomes permanent.
Once the bottom joint is set, install the gasket or ring that sits between the drain body and the subfloor. The 42099 typically ships with a neoprene or rubber gasket. Some older install manuals show a lead or hemp oakum joint instead, but that's for cast iron waste lines, not PVC. Make sure you're using the right seal for the material you're working with. I've seen people on job sites grab whatever gasket is lying around and end up with a drain that weeps every time someone steps on the shower floor. Check which gasket came in the box. If it's missing, Oatey sells replacement seal kits and they're cheap compared to ripping out tile. After the gasket is seated, set the drain into the pre-cut subfloor hole. The hole should be just large enough for the flange to sit on top without excessive overhang. Ideally the flange overlaps the subfloor by about a quarter inch on each side. If the hole is too big, you'll get movement under the tile and the thinset will crack around the flange eventually. If it's too small, you're grinding wood you shouldn't be grinding. I mark the flange outline on the subfloor with a pencil before cutting, then use a router or jig saw. It takes about five minutes extra but it prevents the frustration of going back and filling gaps with epoxy later. When you're raising the floor with mortar bed or a pre-sloped base, the drain needs to be positioned so the finished slope meets the opening at the correct depth. The 42099 flange should sit approximately 1/4 inch below the finished tile surface. Not flush. Not above. Below. The tile and thinset will bring it up to the final plane. If the flange ends up flush or above the tile, water pools around the edge and that's where leakage happens. I always lay a scratch coat of thinset first, set the drain body to the correct height, check the level from multiple directions, and then build the slope around it. The slope should be a minimum of 1/4 inch per foot toward the drain opening.
One detail that catches people off guard is the clamping ring or locking collar that secures the flange to the body. Some versions of the 42099 use a threaded locknut on the underside that you tighten from below the subfloor. Others use a top-side compression ring. If you have access from below, tighten the locknut until the flange is snug but don't overtighten. Overtightening compresses the gasket too much and can deform it, which actually creates a leak path. If you only have access from above, use the compression ring and tighten evenly in a star pattern, not all the way down on one side and then the other. I learned that one the hard way on a second-floor bath where the plumbing chase was tight. The flange was crooked because I torqued the ring unevenly and the tile setter noticed before grout went down. Another thing the manual doesn't always make clear is that the drain body should be installed before the waterproofing membrane, not after. The membrane wraps around the flange or bonds to the gasket surface depending on the system you're using. Cured compound membranes like RedGard or similar products need the flange seated and secured first. Sheet membranes like Schluter-Kerdi require a proper bonding flange and the correct Kerdi drain pan or setup. The 42099 is a generic body style and it doesn't have a built-in bonding flange for sheet membranes unless you add one. If you're using a sheet membrane system, check whether you need an adapter ring. Installing the drain after the membrane goes up means cutting around the drain afterward and you lose the continuous seal the manufacturer designed for. Let me address a specific problem I ran into last year on a bathroom remodel in an older home. The subfloor was 3/4 inch tongue and groove subpanel over joists spaced 16 inches on center, but the shower area had a soft spot because someone had notched a joist for plumbing and the patch wasn't fully cured. I set the 42099 drain and when I checked the level after the mortar bed dried, the flange had settled about 1/8 inch on one side. The tile would have been uneven and the slope would have pulled away from the drain on the high side. The workaround was removing the drain body, cutting a 2x4 spacer block to fit between the joists underneath the drain location, screwing it in tight, and then resetting the drain on a fresh bed of mortar. It added about twenty minutes to the job but it prevented a callback. Don't skip checking for subfloor deflection before you commit the drain in place.
Get the Full Details
Here's a counter-intuitive point that most beginners miss. The direction you thread the drain body into the waste pipe matters less than how you support the pipe during installation. PVC waste pipe expands and contracts with temperature changes. If the pipe is rigidly clamped close to the drain body with no room for movement, thermal cycling can crack the cement joint over time. Leave a small expansion gap or use a slip joint configuration where the code allows it. Also, don't use a primer colored purple on Schedule 80 pipe if the cement you're using is already rated for both Schedule 40 and 80. Some cements are dual rated and adding primer doesn't improve the bond. It just wastes time and creates unnecessary fumes in a confined space. A common pitfall is assuming the drain will self-seal once the tile is installed. It won't. The thinset and grout around the flange are cosmetic and structural, not waterproof. The waterproofing happens at the gasket between the flange and the subfloor and at the cement joint below. If either of those is compromised, tile color won't hide it. Water will find its way through the crack in the grout and into the subfloor. I've torn out enough shower pans to know that a drain that looks fine on the surface can have a slow leak under the ring that's been rotting the subfloor for months. If you're working with a shower pan instead of a curbless or pan-in-wall setup, the 42099 body fits into a standard 4-inch drain opening. Make sure the pan has the correct pre-slope before you set the drain. The pre-slope directs any water that gets beneath the tile bed toward the drain so it doesn't sit against the waterproofing liner. Without a pre-slope, you're relying on the tile bed itself to stay perfectly dry, and that's a harder promise to keep over ten years.
For the actual download of the official Oatey 42099 Shower Drain Installation Instructions, go to the Oatey website product page and look for the installation sheet under the resources or documentation tab. Enter the part number directly. Sometimes the PDF is buried under a form wall that asks for your email before showing the download link. Fill it out if you want it. The instructions are also usually available through major plumbing supply house websites if you search the model number. To summarize the core steps without padding: prime and cement the bottom joint with a medium bodied PVC cement, set the correct gasket, position the drain so the flange sits about a quarter inch below where the tile will finish, ensure the subfloor is rigid and level, install waterproofing around the flange before tiling, and verify the slope directs water into the opening. The whole process takes roughly forty five minutes to an hour for a competent installer on a straightforward remodel. More if the subfloor needs reinforcement or the waste line requires repositioning. Less if you've done this sequence multiple times and know where the common failure points are. The main limitation of the 42099 is that it's a generic body style. It doesn't include the bonded flange that sheet membrane systems require, so you'll need to factor in an adapter or a different drain body if you're doing a full Schluter or similar system. It also only works with standard 4-inch waste connections. If your existing plumbing is 3-inch, you'd need a reducer or a different drain altogether. For a straight PVC or ABS waste line with a traditional mortar bed or pre-sloped pan, it's a solid choice. Just pay attention to the gasket, the flange height, and the subfloor support. Those three things determine whether the drain holds for a decade or needs repair by year three.
