Leak-Proof Shower Floors Installing a CPE Shower Membrane

Leak-Proof Shower Floors

Installing a CPE Shower Membrane By: Tim Carter

©Copyright 2007 -Tim Carter

Table of Contents

Introduction Chapter One Shower Pan Liner History Chapter Two Getting Ready for the Liner Chapter Three The Drain Assembly Chapter Four Framing Tips Chapter Five Installing the CPE Liner Chapter Six Inside Corners Chapter Seven The Curb Copyright Information and Distribution Request

The information in this book strives to be like a plumb bob at rest – delivering true and accurate information to those who look at it.

Over the years, I have come to discover that many of the tasks I have completed and feel are routine actually are a mystery to the vast majority of homeowners out there. To me installing a shower pan liner is as difficult as making a large Sunday morning breakfast with eggs, bacon, fresh biscuits, orange juice, etc. I am the Sunday morning chef at the Carter household. It is not hard to make the breakfast, there is just a certain order in which you do things to make sure all of the food is cooked and ready at the same time. Shower pan liners are no different. After you read this book, I am confident you will feel very confident in your abilities to success-fully install a leak-proof shower pan liner. When you view the photos in this book, I think you will breath a sigh of relief. Get ready, the mystery of shower pan liners is about to be solved for you!

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Introduction

Ceramic tile shower floors leak. They do so each and every time you take a shower. But by no means does that mean they have to leak onto your wood sub floor or onto your concrete slab. Many people think that a ceramic tile shower that is in fantastic structural shape - meaning no cracks in the grout or the tile - is waterproof. Nothing could be further from the truth. Beneath the tile is a bed of cement mortar that sits inside a waterproof membrane. Years ago the membranes were thin sheets of lead. Plumbers with great skills would form the lead sheets to fit precisely into the rough dimensions of the shower. The lead would completely cover the floor and lap up the sides of the wood framed walls. Where two pieces of lead joined together, the plumbers would use a soldering iron and sticks of lead to make a leak proof joint. Talk about craftsmanship! The lead would also be soldered to the brass drain assembly so that, in essence, the lead pan acted as a hidden sink or tub fix-ture. In fact, the plumbers would test the lead pan assem-bly for leaks by plugging up the drain and then filling it with water. They would come the next day and look for leaks. If the assembly was water tight, then the pan was ready for the ceramic tile sub-contractor. But working with lead is a thing of the past. For one, it is indeed a toxic material to work with. No doubt many old plumbers suffered from lead poisoning over time as they worked with lead solder on a daily basis. But the lead shower pans had a built-in liability. Over time, they would develop leaks. It took many years for this to happen, but it couldn’t be prevented. As water would saturate the ce-ment mortar under the tile, it would leach out minerals from the water. This mineral filled water was in constant contact with the lead pan and the metal drainage system. This combination created electrolysis within the shower pan. The electricity generated by this low powered battery would actually begin to corrode the lead. Technology to the Rescue The plastics and synthetic products industries came to the rescue. We can now buy different plastic or rubber-like materials that allow us to quickly install a shower pan liner that is far better than any lead pan. The new prod-ucts are often available in wide sheets — five feet wide or more. This width often eliminates the need for any seams in the average-size shower. This quality alone is a huge advantage over lead. The secondary benefit is that the sheet membrane products will not corrode. Finally, they are very easy to work with. The average person can in-stall a plastic shower pan liner membrane with just a few common hand tools.

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Chapter One - Shower Pan Liner History

The Different Membranes

Shower pan liner materials are quite differ-ent from one another. But some are far better than others in my opinion. Here is a quick review of what is out there: CPE—Chlorinated Polyethylene - This is a permanently flexible rubber-like material that is impervious to water and any chemi-cals you would find in the average home. It is easy to work with and comes with sol-vents that allow you to permanently weld two pieces together. PVC– Polyvinyl Chloride - This is a plastic material that contains plasticizers to keep it supple and pliable. It also can be welded together with solvents. The early PVC prod-ucts could get brittle over time and possibly crack. But many modern PVC liners work well. Hot Mop Asphalt - This is the old fash-ioned hot tar put on roofs. Trouble is, it can crack as the wood framing moves! Sheet Bitumen - This is a mixture of plas-tic sheeting and asphalt. It is similar to the ice dam products you put on roofs edges. It is not easy to work with. Paint-on Plastics - These are liquid mem-branes that you paint over wood or con-crete. These products are the least appeal-ing to me for all sorts of reasons. Code Listing - Be sure that the liner you buy has a Uniform Plumbing Code (UPC) listing. This listing means that code officials approve it since the liner actually is an inte-gral part of the shower drain.

When I first started to install shower pan liners over 25 years ago, I simply swept all debris and sawdust from the sub floor area inside the shower area and got to work. If the sub floor was out of level, I figured that it wouldn’t really make a difference since the liner material was water-proof. So what if water sat in one corner or along one edge? Once the height of the water could reach the drain holes and slots, any excess would go to the drain. Being a master carpenter as well as a master plumber, I did do one thing I never saw any other plumber do. I would use my router to create a depression in the wood sub floor for the drain assembly to drop into. Without this depression, the top surface of the drain would sit up one eighth of an inch above the sub floor. This meant that there would be a constant pool of water in the liner one eighth inch deep at all times. I felt by lowering the drain assembly into the wood, I would at least give the water a chance to get into the drain easily. Now the industry standard is to create a sloped surface on the sub floor that the liner rests upon. This can be done several ways: • Use plaster or an equivalent floor leveling compound to create a low slope bowl shape in-

side the shower area so that surface has fall from all points towards the drain assembly.

• Use a sand / cement mixture similar to what will be used to form the mud pan once the liner is installed. Install it so that the surface has fall from all points towards the drain as-sembly. Figure One shows very clearly this method. The gray colored material inside the shower area is a sand / cement mixture. The reddish-brown border at the edges of the sloped mixture is simply red-rosin paper that was installed to protect the shower pan liner where it would contact the wall framing. The slope towards the drain is very gradual, no more than one quarter inch of fall per foot of run towards the drain. Keep in mind that this slope should be reasonably close but by no means perfect. The cement mud mixture in-stalled after the liner is installed must have a uniform and perfect slope so that the finished ceramic tile is in the same plane.

• Purchase a factory-made kit that lays on top of the sub floor and automatically creates the necessary slope once you trim it to fit the shower area and the drain assembly. These fac-tory kits are often sold at tile stores or plumbing supply houses that carry the superb CPE liner material. The kits are made with a dense foam that has the code-approved slope built into the product. The weight of the liner and the cement mud installed after the liner is in-stalled hold these kits in place.

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Chapter Two - Getting Ready for the Liner

Figure One

You can buy the best liner, fit it perfectly, fold the corners as good as any professional, but if you do not have the correct drain assembly that accepts the liner, you are toast. Figure Two shows a typical shower drain assembly that is made for shower pan liner membranes. This drain consists of three pieces. The part in the center is the primary drain receptacle. All water is funneled to the center of this part, drops down the hole and from there into the P-trap that is below the floor. If you could look down the hole in the center of the part right now, you would see the standing water in the drain trap. The circular part to the right that has a hole in

the center and the four keyhole shaped slots is the clamping ring. Once the liner is cut to fit the drain hole - a very precise procedure - you install the clamping ring and tighten the four silver bolts to make a watertight connection between the drain assembly and the membrane liner. The strainer is the dark colored part. It is a threaded part that screws into the clamping ring. The screws allow you to adjust the strainer to the height of the tile. The strainer in this photo has a protective dark plastic over the polished chrome strainer plate. Once the tile job is com-plete and all grouting is done, you remove the plastic. If you remove the plastic at any other time, you run the risk of scratching the polished chrome.

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Chapter Three - The Drain Assembly

Figure Two

Clamping Ring Strainer

The first liner I ever installed came out great except for one thing. I folded the membrane liner corners as the manufacturer suggested. I then applied my one-half inch thick cement board over the membrane and held it up off the cement mud floor one quarter inch. I thought at the time that the cement board seemed to bulge out at the corners ever so slightly. When I went to install the tile the next day, it was painfully obvious that the cement board did bow out slightly at each corner. I had to cut my corner tiles at a slight angle to compensate for this problem. As I was cutting the tile, I thought to myself, “Heck, I could have easily tucked the liner back into the framing if I had left a small space.”

Figure Three clearly shows a gap be-tween wall studs that can really help you make your tile walls perfectly straight. When you, or the carpenter, frame the walls for the shower, simply hold one wall stud back one-half inch from the corner. The half inch gap pro-vides plenty of room to tuck the liner into the wall cavity. Remember, once the other sides of the shower walls are finished, you will never see the liner that is actually in the wall corner cavi-ties. While on the subject of wall framing for tubs and showers, here are some valu-

able tips:

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Chapter Four - Framing Tips

Figure Three

• Use perfectly straight studs. Consider metal studs if necessary. Perfectly plumb and straight walls make for perfect ceramic tile installations.

• Studs laid out on 16 inch centers produce a 14.5 inch space between the faces of the studs. Make sure that the center of one of the spaces is lined up exactly with the centerline of the faucet. It is nothing but trouble to notch a misplaced wall stud that is in the way of the shower valve.

• Place an extra stud at or immediately adjacent to the edge of the tub or shower enclosure. In fact, place two studs side by side. You want solid framing where the cement board will stop and any moisture resistant drywall will begin.

• Place a stud in the centerline location of where a shower door might be. You want the shower door tracks to screw into wood, not air.

• Place plenty of 2x10 or 2x12 blocking in the walls to accept grab bars for physically challenged individuals. Buy the grab bars before you frame and note the spacing so you know where to place the blocking. Take photos after the blocking is up so you know where it is after the tile is complete.

Your wall framing is right. There are gaps at all corners, including where the curb intersects the walls. The sub floor is sloping to the drain. You are ready my friend for the payoff. It is time to install the membrane liner. I am very partial to the CPE membrane material. It is easy to work with and I love the way I can weld pieces together with a solvent. I always buy the shower membrane called Cloraloy®. This product is in my own home in my master bathroom shower. It has performed flawlessly for 16 years and I expect it to last the lifetime of the home. You can order this product online, if it is not readily available in your town or city. The first step is to purchase a piece large enough so that one solid piece will do the entire job. Some showers are so large they may require seaming two pieces together. As you can see in Figure Four, one piece of Cloraloy® was able to do this shower pan. Note how I have it loosely laid in the shower pan area. I used the handy blue lines to insure that the membrane is laying square within the framed opening. You want the liner to lap up onto the walls a minimum of six insches. Eight inches lapping up the walls would be preferrable. If your shower is too wide for one piece, it is highly desirable to see if you can center the main sheet and get this sheet to lap slightly up onto each wall. I would always want a seam to be on a wall if at all possible rather than on the actual floor area of the shower pan. Since the liner membrane is manufactured in huge rolls many feet long, you should always be able to get the liner to lap up high enough onto at least two opposite walls without seams. Cut the Drain Hole First I always prefer to cut the drain hole out first. Perhaps it is because I want to be fresh and alert during this very critical step. With the liner squared in the opening, kneel inside on the liner and use your hand to feel the drain assembly. You cut a small hole first in the center of the drain and slowly begin to make successive cuts that enlarge the hole. Figure Five shows this initial cut. I use a standard razor knife to cut the CPE membrane material. The margin for error once you are making your final cuts is less than one quarter of an inch. It is imperative that you cut slowly and carefully. Figure Six shows the first hole completed. You

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Chapter Five - Installing the CPE Liner

Figure Four Layout Lines

Figure Five

can see down into the drain hole. The diameter of this hole is approximately two inches. The final diameter of the hole will be approximately four to five inches so you see there is still much to cut. If you look at the white clamping ring in Figure Six, you can get an idea of how large the final hole must be. The final cut must be a circle that stops at the outside edge of the small slot in the four keyhole shaped knockouts you see in the clamping ring. As you can see, there is very little white plastic between these points and the outer edge of the ring itself. The bolts that are used to clamp the ring are excellent reference points as you enlarge the

hole. Figure Seven shows the final stages of the cutting process. Note how the cut follows the curve of the sloped part of the drain assembly. The cut is also made just on the outside edge of the treaded holes that the bolts screw into. You need to cut to this point so that the water that leaks though the tile, grout and into the cement mud can find its way to the weep holes. Figure Eight shows the hole successfully cut and the clamping ring in place. There are eight weep holes locations on the ring. Note the four holes at the 12, 3, 6 and 9 o’clock positions on the ring. Water can flow down the tiny grooves into the hole and down into the drain. The other four holes are the large holes made for the bolt heads. You can see in Figure Eight the reflection of the standing water in the trap below. You should also be able to see how any water that would flow across the CPE membrane would go

immediately to the holes and drop into the drain. The clamping ring bolts, once tightened, make a waterproof connection between the drain assembly and the clamping ring. Do not overtighten these bolts! You can crack the plastic clamping ring.

Figure Six

Final cut stops here

Figure Seven

Threaded Holes

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Figure Eight

Believe it or not you are almost finished with the job of installing the liner. This is especially true if you have a standard square shower. The one that is illustrated in this EBook is a little differ-ent as it has a clipped 45 degree corner and the CPE membrane laps up two walls and onto a whirlpool tub deck! But don’t let that confuse you for now. 99 percent of most showers have four simple inside corners. The next step is to work on the inside corners. Figure Nine shows you what happens when you turn the corner with the liner material. You end up with excess material at an inside corner. The ex-act opposite happens when you try to go around an outside corner. When you try to go around an outside corner within a shower, you don’t have enough liner to make this happen. You are forced to cut special patching pieces. These same patches are required when the membrane goes up and over the shower curb. We will be discuss-ing this shortly, so be patient. The excess material in Figure Nine is what caused my cement board to bulge out as I discussed earlier in this EBook. I think you can see why this would happen as there would be three layers of membrane material squeezed be-

tween the wall framing and the cement board. That may not seem like a lot of material, but it makes a difference. Study Figure Ten. The wonderful gap in the fram-ing at the corner allowed me to tuck all of that ex-cess material back into the wall cavity! There is a slight wrinkle of membrane material at the corner but it will in no way interfere or cause the cement board to bulge once it is applied over the liner. See how crisp the inside corner is where the floor meets the wall framing? This is what you are aiming for. Trust me, it is not hard to achieve. Also, look at the

blue layout lines. See how the ones on the floor are parallel with the wall to the left? I have also started to tack up the liner on these two walls so it does not flop back down into the shower area. I happened to use a staple gun and held the staples very close to the top edge. Galvanized roofing nails could have been used as well. Once you have the first corner com-plete, move on to any others. You will quickly discover it takes less than 30 seconds to tuck the liner material into the corner gap.

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Chapter Six - Inside Corners

Figure Nine

Figure Ten

Oh you are so close now. But you need to be alert during the final steps. Up until this time, we only had to cut the CPE liner at the drain opening. But as the CPE membrane starts to bend over the curb, you run into a situation where the liner must be cut. Don’t worry, you can and will deal with this challenge. Figure Eleven shows the CPE membrane wrapping over the curb that stops water from flowing out of the shower and onto your bathroom floor. I have drawn a dashed black line on the liner membrane to show you where I am going to cut it. Cutting the membrane allows it to lay flat on the top of the curb. It also allows some of the mem-brane material you see on the wall to over-lap onto the top of the curb. The membrane material in the inside corner on the shower side of the curb can be tucked into the gap in this corner.

Figure Twelve shows the cut. I have sliced the material so that the CPE membrane can lay flat on the top of the curb. The crease you see in the photo flattened out after I took the photo. It did so as soon as I adjusted the liner material. The excess membrane material on the wall will fold back into the gap in the framing in the corner. The flap of cut material that is being held in place by my thumb will remain up on the wall. This leaves the triangle of wall exposed without any membrane. We solve that by cutting a patch of membrane.

The patch is cut from scrap membrane material that was trimmed from one of the ends of the membrane. I always order an extra foot or two of material so I have plenty of scrap on hand. Figure Thirteen shows a square patch of membrane material. It is approximately two inches square in size. I have made a cut in the patch that begins on the centerline of one edge and extends in a straight line into the center of the patch. The patch is going to be applied to the membrane so that the flap I am peeling up-wards will lay on the curb while the other 75% of the patch adheres to the membrane on the wall. The point is to overlap the patch on the liner membrane so that you do AsktheBuilder.com

Chapter Seven - The Curb

Figure Eleven

Figure Twelve

Figure Thirteen

Cut Stops Here

not have a hole in the liner where the original angular cut was made that you see in Figure Twelve. Keep in mind that you do the exact same thing at the other end of the curb. It basically is a mirror image of the curb end you see in Figures Eleven and Twelve. Solvent Welding the Patch The CPE Cloraloy® on this job uses a solvent made by the same company. It is called Nobleseal®. It is a clear chemical that has the viscosity of water. You apply it to the printed side of the Cloraloy® that you see in the photos. The chemical evaporates very quickly but as you spread it around with the swab that comes in the can, it softens the Cloraloy®. You apply some Nobleseal® solvent to the smooth side of the patch as well. You will notice that as the solvent evaporates the membrane gets sticky. It is time to react. Place the patch on the membrane so that the two sticky faces touch one another. You will have about five or possibly ten seconds to orient the patch in the right position. Press firmly with your fingers to make the two pieces weld together.

Figure Fourteen shows the patch in position. I used the black marker to make dashed lines so you could see the outer edges of the patch. Without the black dashed lines, it would be nearly impossible to see where the patch overlaps the membrane. The membrane has actually been folded over the side of the curb that faces the bathroom. I used a few staples to hold it in place until such time as I could nail the cement board over the membrane.

Victory! Figure Fifteen shows the shower liner completed. In fact, it shows the cement mud bed already poured in the liner! If you want to learn how to do that job, you may need my Cement Mud Floor for Ceramic Showers EBook. Click the title to get it. But before you do, join me in a toast for a job well done. On the whirlpool ledge, you can see a delightlful glass of Wild Cherry Pepsi with crushed ice that I have waiting for me. Bottoms up!

Figure Fourteen

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Figure Fifteen

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