Create added comfort and convenience in your motorhome’s bathroom by increasing the height of the toilet.
By Ken Wilson, L13812
July 2002
If you are very tall or have arthritis or other problems with your knees, hips, or back, you may have found that the typical RV toilet’s height is just a bit too low to be comfortable.
The RV industry has been very responsive in recognizing the special needs of people with problems such as these. Among the solutions are high-rise toilets, seats that are a few inches thicker than normal, spacers that fit between the toilet and the floor, and toilets mounted on raised platforms. In our motorhome, the toilet seat measured 15 inches from the floor, just a bit too low to be comfortable. We are both tall, and since I had the unpleasant experience of dislocating my replaced hip last year, I’m really careful. The original installation is shown in Image A. I did not want the expense of installing a new high-rise toilet, and an extra-thick seat was not available for my toilet model. The commercially available spacers wouldn’t provide enough height to suit me. That left me with one option: to build something that would raise the toilet.
My wife, Pat, and I decided how high to raise the toilet by placing large coffee table-type books on top of the toilet seat. We kept adding and removing books until we achieved the most comfortable height. We decided that we wanted a total height of 21 inches, an increase of 6 inches.
The floor in our motorhome’s bath area is covered with 12-inch-square ceramic tile. I decided to make a plywood box that would sit directly over the original sewer opening and be securely attached to the coach floor. The toilet would be mounted on top of this box.
Our coach is a 1999 American Tradition with a SeaLand Traveler Model 910 toilet. While the techniques I used are specific for this coach, with slight modifications they should apply to most other coach-and-toilet combinations. The combination of plumbing fittings that I used was the result of a great deal of poking around the plumbing sections of home-improvement stores. Several combinations of parts, however, will do the job.
Getting started
My starting point was the closet flange on the coach’s floor. First, I located another flange of the same type, and then tried combinations of fittings until I found one that would do the best job.
One of the first steps I would recommend is to dump your black-water holding tank, and then fill it and dump it several more times. With a clean tank, the time you spend working over the open plumbing will be much less objectionable.
Next, turn off the water to the toilet. If your coach builder has provided separate shutoff valves for each water outlet, you merely have to locate and turn off the valve in the toilet’s water supply line. But if your coach is like most, you will have to turn off the entire water system at the external hookup. Remember to turn off the water pump and cover all the switches with masking tape to avoid an accidental flood.
Once this is done, flush the toilet or turn on a faucet to relieve pressure in the water system, and then remove the toilet’s water line. When you remove the water line, have a small pan or a towel ready to catch any water that might drain.
If you need your kitchen or bathroom sink, cap off the toilet’s supply line and turn the water back on for the rest of the coach.
Before you remove the toilet, a discussion of how the typical toilet is attached to the motorhome’s waste plumbing might be in order. A circular fitting called a closet flange is screwed or glued onto the upper end of the sewer pipe. This flange makes the actual connection between the waste pipe and the toilet. It is securely attached to the floor of the motorhome with screws or bolts. There will be a seal between the flange and the base of the toilet to keep gas and liquid from leaking. This seal is often a wax ring, but some manufacturers use rubber seals. The heads of hold-down bolts are slipped into slots in the closet flange with the threaded ends sticking up. The toilet sits over the flange, compressing the seal, with the bolts sticking up through matching holes in the toilet’s base. Washers, nuts, and decorative caps fit over the ends of these bolts to help anchor everything securely to the floor. Some RV toilets, such as our Traveler, have decorative covers over the bases of the toilets and the bolts.
Remove the decorative cover, if applicable, and unscrew the nuts from the hold-down bolts. This hardware might be rusted, so be careful not to damage the base of the toilet. Have a rag ready to stuff into the sewer opening to stop any odor from escaping and to keep anything from falling in while you are working. The closet flange with the original flange bolts and seals are shown in Image B. Carefully remove the seal and set the toilet aside while you build the support. (This would be a good time to give the toilet a good cleaning and fix any possible problems, such as water leaking out of the bowl between uses.)
Box construction
The actual construction involved in this project can be broken down into two parts. First is the carpentry necessary to build a box to serve as a foundation for the toilet in its raised position. Then there is the plumbing necessary to extend the water supply line and to connect the new closet flange mounted on the box to the original closet flange mounted on the motorhome floor.
The box will have to be as large or larger than the base of your toilet. This will provide a solidly mounted toilet that will not rock and cause damage to the plumbing or leaks in the seal. My support was a 12-inch-by-12-inch box made of 3/4-inch oak cabinet plywood. Most home-improvement stores have plywood available in 2-foot-by-2-foot or 2-foot-by-4-foot pieces, so you do not have to buy a whole sheet. I mitered the corners and used matching oak molding to trim the exposed edges of the top piece.
I decided to make the box in two pieces. One part consisted of the four sides with the necessary glue blocks to strengthen the corners and serve as mounting flanges. The other part was the top, with decorative molding trim covering the exposed edges. I assembled the four sides of the box with glue and finishing nails. The two parts of the box are shown in Images C and D.
Center the hole for the new closet flange in the top of the box and cut it out. Set the heads of the finishing nails below the surface, and use wood putty to cover them and any other imperfections. Give everything a good sanding to remove all splinters and rough spots. Then apply several coats of a good finish, such as the satin polyurethane varnish I used. This will seal the plywood and help to prevent it from being damaged in the event of a leak. The completed box is shown in Image E.
Put the box in place and check to see that the hole for the new flange lines up with the original flange.
Plumbing
Now that the box is finished, it is time to start on the plumbing connections. However, before you do this, one more rather unpleasant job remains. You must thoroughly clean the coach’s flange. This is necessary to make it possible to have a secure and leak-proof joint between the flange and the added plumbing. The best way to clean the flange is with a pair of rubber gloves; a putty knife; an old sponge; and a bucket of warm, soapy water with a little ammonia or household bleach added.
You need to make a leak-proof connection (both gas and liquid) between the old and the new closet flanges. Take a close look at the bottom of your toilet, the top of the original closet flange, and the old seal before you decide how you will do the plumbing. If the bottom of the toilet resembles the bottom of a household-type toilet, you should be able to use a household-type closet flange and a wax ring seal. If not, you probably will have to use a flange and seal designed for your brand of toilet. The plumbing department of a hardware store or a well-stocked RV parts store should have what you need.
Many different sizes and types of closet flanges exist. The ones designed for household use are commonly available for 4- and 3-inch-diameter pipe, including a combination flange that will work with both sizes. They are also available in an offset style to allow placing the toilet a few inches out of line from the pipe. The ones designed for RVs generally are for use with 3-inch pipe and may be designed for either threaded or glued fittings. These RV flanges often come in a variety of styles, because each is intended for use with a specific brand of RV toilet.
There are several ways to attach your new sewer to the existing flange. The first possibility is a special type of closet flange designed to facilitate repairs to damaged household installations. The upper part looks like a normal flange, but the lower end has a threaded and tapered connection around which a wide rubber gasket is attached. It is designed to be inserted into the sewer pipe after a damaged flange is removed. To assist in making a leak-proof connection, the rubber gasket can be twisted up on the threaded taper so that it gradually increases in diameter. Once the gasket fits inside the pipe, twist the flange to expand the gasket, making a very tight seal. Then you can anchor the new flange to the floor. This makes it possible to fit it inside several sizes of pipe and form a secure connection. Before you decide to use this method, however, make sure it will fit into the space you have available.
Another possibility is to use two new closet flanges that are connected with a very short piece of pipe. The tapered outside surface of the new lower flange simulates the bottom of the toilet. This might possibly allow the use of a new wax ring to seal between the inside tapered surface of the original flange and the outside surface of the new lower flange. The problem you could have in using this method is the limited space available. You probably will want to raise your toilet just a few inches, so you have to be really careful to get the connection plumbing to fit.
There is a third possibility to be considered. Carefully check the original flange to see whether it would be possible to attach a short piece of pipe that would stick up through the box. This new piece would have to be attached securely to the top of the coach’s flange so that it does not leak. Ideally, it should be glued to the original flange using the appropriate glue for the materials you are using, such as PVC cement. PVC cement is rather final, which could create a problem if you ever wanted to remove your modification, so it might also be possible to seal the new short extension to the original flange with a heavy bed of silicon glue/sealer. After this short extension is attached and sealed, the box is installed and attached to the floor. Then the new flange is glued to the short extension and securely attached to the top of the box with screws.
Before you decide on which method you will use, you must carefully check your measurements, the design of the existing toilet and closet flange, and the parts you have available, and then consider the pros and cons of each method. If you have decided to use the flange with the adjustable rubber gasket, carefully follow the instructions and make the necessary adjustments to ensure a tight seal. If you use a combination of two new flanges connected with a piece of pipe, make sure that everything fits correctly in the space available and that you can make a leak-proof seal. If you pick the third method of a short extension pipe glued into the original flange, make sure your measurements are accurate. No matter which method you use, the new flange must be securely attached to the box with screws or bolts.
I decided to use the third method, a short piece of 3-inch PVC pipe attached to the coach flange, sticking up through the box and glued to the new flange. I was concerned about the seal between the pipe I added and the coach’s flange. This is the reason I decided to make my box in two pieces, so I could check the seal after it had hardened.
Once I had the box finished, I decided to use screws down through the mounting blocks into the floor. I originally intended for the screws to go through the grout between the floor tiles, but I ended up having to drill through the tiles. Use extreme care and the proper masonry bit when drilling through tile flooring so that you do not break any tiles. I used 2-inch deck screws to go through the 3/4-inch mounting block and the 1/2-inch floor tile into the coach’s subfloor. Deck screws work well, because they come in a wide variety of lengths and rust-resistant finishes.
To make a more secure attachment, I ran a small bead of glue/sealer around most of the lower edge of the box before I screwed it to the floor. I did not run the bead all the way around, because if a leak occurred, I wanted to be able to detect and fix it before real damage was done. The lower part of the box mounted on the tile floor is shown in Image F.
After you mount the lower part of the box, dry-fit your plumbing connections before you glue anything together. The 3-inch pipe could have been attached directly to the coach’s flange, but I discovered that if I used a 3-inch connector on the lower end of the pipe, it would serve as a bushing and make a better fit and a much tighter connection. The total length of the two connectors (the one that fits into the coach’s flange and the one that fits on the new flange) would be longer than I needed, so I simply trimmed the lower one slightly so that everything fit.
If you use my method, dry-fit the lower connector into place with a short length of pipe. Temporarily put the top of the box into place, slip on the upper connector, and see whether the new flange will fit into the upper connector, with the lower edge flush with the top of the box. If everything fits, you are ready for the next step. If not, make the necessary adjustments by trimming one or both of the connectors or the joining pipe.
Once the dry fit proves that the measurements are correct, remove the top of the box; use PVC cement to glue the two connectors together with a short piece of 3-inch pipe; and attach the connector/pipe assembly to the coach’s flange using silicon sealer, such as Plumber’s Goop. Use plenty of the sealer, because this is one connection that you do not want leaking. Before the sealer dries, make sure the pipe is properly aligned with the hole in the top of the box. The advantage of the PVC cement is that it makes an extremely strong and leak-proof joint that is ready to use almost immediately. The advantage of the silicon glue/sealer is that it gives you plenty of time to move things around to get them lined up before it sets. Image G shows the extension glued to the coach closet flange.
Do not glue the upper flange on at this time, because you will first have to attach the top of the box!
Attach the top of the box to the sides and make sure the new plumbing is centered on the hole in the top of the box. I used 2-inch-long #8 screws with decorative washers. Make sure you first drill pilot holes or you will probably split the sides of the box.
Once the top is mounted, glue on the upper flange. Before the silicon glue dries, make sure it is positioned so the hold-down bolt slots are in the right place.
Attach the new flange to the top of the box with screws. I used 1-inch-long #12 flathead screws for this job. Image H shows the top of the box installed, and the new flange glued to the extension pipe and screwed down to the top of the box.
Next, if you are lucky, the supply line in your coach will be flexible and have enough extra length so no change is necessary. In my case, the rigid plastic supply line came up through the floor and included a couple of elbows before it reached the connection on the back of the toilet. To get the necessary height, I cut this line and added a short piece of the same size and type of plastic tubing. Our coach was plumbed with QEST Pex tubing, brass fittings, and heavy clamps put on with a special tool. I went to a home-improvement warehouse intending to get barbed connectors and screw-type clamps to make the connections, since I did not have the necessary tool to clamp the joints. There, I found that QEST makes a variety of plastic fittings that can be installed with hand tools. I was able to use several inches of the Pex tubing, one elbow, and one connector to get my job done.
If your coach is plumbed with another type of water line, you might be able to use barbed connectors and screw-type hose clamps to add the necessary length. Just make sure the tubing has a pressure rating high enough to handle the wide variety of water pressures that you are sure to encounter in your travels. You should use quality clamps, preferably stainless steel, because they will be in a rust-prone area, and you will really have to tighten them down to make everything leak-proof. If your box covers the water supply line, you will have to drill a hole in the top surface of the box. You should plan all the water line connections so that they are above the top of the box. This makes it easier to spot any leaks.
Reattaching the toilet
Once everything is completed and checked out, it is time to reattach the toilet. Install a new seal of the proper type. Install new hold-down bolts if the original ones are rusted. Image I shows the new hold-down bolts and rubber seal. If there is room, the next step might be easier if someone guides you when you align the bolts with the holes in the toilet’s base. Carefully lower the toilet onto the threaded ends of the bolts. Do not move it around as it is lowered, because this might damage the seal and prevent it from doing its job. Compress the seal until the toilet’s base makes contact with the top of the box. Sitting on the toilet seat is an easy way to do this. Once the toilet is firmly seated — no pun intended — place the washers and nuts on the bolts and carefully tighten them. Do not use excessive force; just tighten until they are firm. Anything more might crack the base of the toilet. Image J shows the toilet bolted down and ready for the decorative covers.
Reattach the water line to the fitting on the back of the toilet. Carefully turn the nut onto the fitting’s threads so you do not cross-thread it. When you use pliers or a wrench to tighten the nut, do not overtighten it, especially if it is plastic. Use only enough force to firm it up.
When you turn on the water supply, carefully check for leaks. If it is hard to see, use a flashlight and a small mirror. If the fitting is leaking, a partial turn on the nut should stop the drip.
The cost of this project was less than $50, including the plywood and all the plumbing fittings. It does take a bit of time to do the planning, and to pick out the combination of fittings that you will be able to use. However, this small investment of time and money will make your coach toilet much more comfortable and convenient.
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How To Increase The Height Of Your Toilet
1. Empty your black-water holding tank.
2. Clean the holding tank by filling and dumping it several times.
3. Turn off the water to the toilet.
4. Relieve the water pressure in the water system, and remove
the water line.
5. Remove the toilet.
6. Construct a box that is the same size or larger than the toilet’s base.
7. Determine the position of the new closet flange; mark and
cut the hole.
8. Set heads of the finishing nails below the surface.
9. Cover the nail heads and any other imperfections with wood putty.
10. Sand, stain, and apply polyurethane to the box.
11. Make sure the new flange hole lines up with the original flange.
12. Clean the coach flange.
13. Determine how you will do your plumbing for a leak-proof connection.
14. Mount the lower part of the box to the floor.
15. Check your measurements by dry-fitting your plumbing connections.
16. Remove the box top.
17. Glue the two connectors together with PVC cement.
18. Using silicon sealer, attach the connecter/pipe assembly to the
coach’s flange. Make sure to create a leak-proof seal.
19. Make sure the pipe is properly aligned with the hole in the top of
the box. Do this before the sealer dries.
20. Attach the box top.
21. Glue the upper flange on, making sure the flange is positioned so
that the hold-down bolt slots are in the right place.
22. Attach the new flange to the box top.
23. Lengthen the supply line if necessary.
24. Install the new seal.
25. Install the hold-down bolts.
26. Lower the toilet onto the threaded ends of the bolts.
27. Carefully tighten the washers and nuts on the bolts.
28. Reattach the water line.
29. Check for leaks and tighten fittings if necessary.