E.H., Atkinson, N.H.

A. Use caulking. While grout is the traditonal, old-fashioned but best way of filling the joint between tub and tile, it is effective mainly if the tub is a porcelain enameled cast iron tub. For your fiberglass tub, caulking is the better fill-in.

The reason for this is that the cast iron and ceramic tile are relatively stable, with a minimum of expanding and contracting because of temperature changes, which is the main cause of grout failure. Fiberglass, on the other hand, may expand and contract faster and greater than cast iron, requiring the use of the flexible caulking instead of the rather rigid grout.

Q. The joint between my tub and tile is caulked. The tub is fiberglass. What is best to use in that joint?

E.H., Atkinson, N.H.

A. Use caulking. While grout is the traditional, old-fashioned but best way of filling the joint between tub and tile, it is effective mainly if the tub is a porcelain enameled cast iron tub. For your fiberglass tub, caulking is the better fill-in.

Q. The caulking around the soil pipe failed where it comes up through the roof, so the ceiling below cracked and sagged. How can I fix the ceiling? It is in a small bathroom.

E.R., Needham

A. I suggest taking down the entire ceiling, putting up plasterboard (a so-called dry wall) and applying two coats of white latex ceiling paint. Or, use Greenboard as a more waterproof dry wall. Or, to get fancy, apply Blueboard and have it skimcoated. Ordinary dry wall and paint will work as well as anything.

Of course, I hope you had the leak fixed. You mentioned caulking around the soil pipe where it comes up through the roof. If it were just caulking, it will never stay leakproof.

Flashing sleeves are made for soil pipes. Measure the diameter of your pipe and buy a sleeve to fit it. The sleeve is a rubber doughnut with an aluminum flashing flange.

Q. My bathroom sink works OK, now it doesn't hold water. The stopper doesn't seem to be seating properly in the drain opening. I bought a new pop-up stopper, but that doesn't work either. Now, what can I do? I did not replace the arm that operates the stopper.

CALLER, with a leaking sink

A. You may not have had to replace the pop-up, if it can be removed by pulling it up. Clean the stopper of debris, hair, oil, and other gunk that may be stopping the stopper. Use a bleach and water solution. Also pour a cup of bleach in the drain to dissolve more grease and hair. Use a big bottle brush to clean the drain. Wear skin and eye protection when working with bleach.

If that doesn't work, adjust the lift rod and pivot rod that are under and behind the sink and operate the stopper. Sometimes the lift rod gets bent in an ``up'' position. You may be able to bend it a bit back where it belongs, or if not that, adjust it by loosening a set screw and lifting the rod slightly, and resetting the screw.

If the stopper is attached to the pivot rod, adjustment of the rods is the only way you can get it to work again.

Q. I saw in your column recently a formula to use to clean a tub, which you said works wonders. Wouldn't you know it, I mislaid the column and have to ask what that formula is.

ANNA PETRILLO, Quincy

A. That is the story of the handyman's life, it seems, but here it is, and I know it works because I used it years ago to clean a ``hopeless'' tub, and it has been pristine ever since.

Wet the surface with hydrogen peroxide, then sprinkle a lot of cream of tartar (a baking product, sold in supermarkets) on the wet surface. Let it be for an hour or so, then scrub and rinse. This will not restore the shine to the porcelain enamel; nothing will, but the tub will be clean and bright.

Q. I would like an exhaust fan in my bathroom. Where should it go in the ceiling? And how can it be exhausted outdoors? Could it be exhausted through the wall?

PAT CASELLA, Bedford

A. An exhaust fan should go as close to the middle of the ceiling as possible, not in a shower area. To exhaust it outdoors, it is best to place the duct on the attic floor, between joists and exhausting out the soffit, the underpart of the roof overhang. And don't just let the duct end in the soffit; that way excessive warm, moist air will fill the soffit and could cause decay. The duct should be secured in a hole drilled into the soffit, so the air will be exhausted directly outdoors.

Another way to do it is to extend it through the roof. And, another type of fan can be installed in the wall, with an automatic door closer on the outside when the fan is shut off. One brand is NuTone, widely available.

Q. How can I get the soap scum off my glass shower door? I tried Dow Bubbles and Glass Plus without success.

M.O., Derry, N.H.

A. Try Soft Scrub, paint thinner or kerosene. Or apply baking soda with a damp cloth.

Q. Water condensed on the bottom frame of one of my French doors, turning it black. The finish is treated with Watco oil. How can I restore that door and keep it from happening again?

MARY ANN BARATTA, Belmont

A. Water will turn any oil finish black in a very short time. Removing the stain is difficult. First, sand the finish as thoroughly as possible, down to the bare wood. This may reduce the stain but will not eliminate it. Then apply bleach. After it dries, rinse with water. After that dries, sand down the grain raised by the water in the bleach.

Re-treat with Watco oil; several coats may be necessary to get the color as close as practical to the old part of the door. If a color match does not work with the oil, stain the bottom part with an oil-based penetrating stain to try to match, then apply the oil.

If the black is not reduced to your satisfaction, this is what to do next: Sand the entire face of the door to the bare wood, and apply a stain dark enough to disguise the black stain. Then re-oil. The only problem with that is that the new finish might not match that on the other door. Oh, well.

Q. I have a set of atrium doors totaling 12 feet wide, installed six years ago. They are now totally warped and look as if they are kicked out at the bottom. I was told they were made in Texas and that the company has gone out of business. Is there any way I can straighten them out? They face the water.

R.A., Hingham

A. Warping is the bane of a door's existence, especially a wood one, and especially one near the water. The wood expands as it gains moisture and contracts as it loses the moisture. The warping is most likely as the wood contracts.

The standard procedure to prevent this movement is to paint the doors on all surfaces -- both faces and all edges, including the top and bottom edges -- when the doors are dry and at their smallest. This prevents the intake of moisture. And sometimes it works. Fortunately, for various reasons, most wood doors do not warp.

Enough as to why the doors warped. If they are not warped too much, you can install additional side stops (the molding that allows the doors to close in the right position), keeping them weathertight.

Or, you can try dewarping the doors by laying them (curved side up) on a flat surface and putting heavy weights on them for several days, maybe even for a week. But you have to be careful with this procedure because the doors are mostly glass, and dewarping them could break the glass. But if you do it slowly, chances are the glass will stay intact.

Q. I was told I can straighten out some warped doors by soaking them with wet cloths and setting them on a flat surface with lots of weights and leaving them for several days. Is this one way to do it?

E.P., North Attleborough

A. It is one way, but wet cloths may not be necessary and could ruin the finish of the door. So simply lay the doors, warp side up, on the floor and put the weights on. Do this now when the doors are at their driest and smallest. They warped when they dried out, so if they flatten out, they might stay that way. If they do flatten out, finish them on both sides with a good primer and latex paint or stain and varnish, but be sure to finish all edges: sides, top, and bottom.

Another trick is to suspend the door on sawhorses, so heavy weights will reverse the curve, adding to the chance of straightening out the door.

The thicker the door, the more difficult it is to sraighten it, or at least it will take more time weighted down to straighten.

Sometimes there is a way around a warped door, particularly if it is an interior door, and the warp is not too severe. And that is to remove the stops, small trim moldings along the side jamb and toe jamb. These stops keep the door in the right position when closed; they literally stop the door. Remove the stops, place the door in the closed position, and renail the stops against the door. The stops can follow the curve of the warp, if it is not too severe, and no one will know the difference. This is not easily done on an exterior door, because the side and top stops are built into the jamb, and cannot be adjusted or moved. But if the warp is not severe, you might be able to nail weatherstripping against the outside of the door. This weatherstripping will cover any gaps and help the door remain airtight, or nearly so.

Q. I am moving into a house that has redwood clapboards in the shower. I don't think they are finished but they are badly stained by soap; the scum is horrendous. How can I clean it? Can I sand off that soap scum instead of cleaning it? And once it's clean, should I finish it?

R.W., Framingham

A. Redwood is resistant to water and decay, but that's about all. To clean off the soap, apply paint thinner or kerosene liberally, and leave it on for several minutes so it can dissolve the soap. Wash with the cloth with which you applied the solvent, then wipe it dry with a dry cloth. Use lots of ventilation when doing this. Sanding without cleaning first will gum up a lot of sandpaper, but it won't hurt to try. I think it is better to clean first, then sand the residue. I suggest finishing it with two or three coats of high-gloss, oil-based urethane varnish. This will darken the redwood but will make it more washable.

Q. What kind of plasterboard should I use for a new bathroom ceiling: Blueboard or Greenboard? One contractor wants to patch the plaster and then paint. Would that be acceptable? The house was built in 1964 and the ceiling is real plaster.

JULIE SANTOS, West Peabody

A. Blueboard is used when a skimcoat of plaster is applied. Greenboard is a water-resistant gypsum board that is used behind tiles. If you plan to have the ceiling skimcoated, use Blueboard; it has a sort of sandpapery finish that allows the skimcoat to stick.

If the contractor fills in the damaged areas of the present ceiling, that is OK, but I don't think it is a good idea to try to skimcoat the plaster, since it may not stick very well. And if you paint over the old paint, you might have difficulty keeping it on it. Over the past 34 years a lot of paint will have been applied to that ceiling. Paint is weight, and many coats can pull themselves right off.

Q. One of the four bolts holding down my toilet is loose, although the toilet is quite stable. How can I tighten that bolt; it just keeps turning.

A.R., Braintree

A. Those bolts are screwed into holes in the metal flange that surrounds the drain hole under the toilet, and I think the bolt opening is stripped or the flange is cracked or broken.

The connection may be OK for a while even with one bolt loose, but it would be better to check that flange and replace it if necessary so all bolts hold. In fact, there is a special spanner-type flange on the market that can be slipped under the broken flange to provide the proper hole for the loose bolt. The spanner flange is made by Fernco, and is sold in home centers and plumbing supply shops.

Q. The toilet is wobbly in my condo. It is set in a concrete floor, and I noticed there is no nut on one of the bolts that was cut off to within half an inch of the base. How can I stabilize the toilet?

P.K., Brookline

A. There is nothing quite so discombobulating as a wobbly toilet, or one that slants to one side, or toward the back or front. If the bolt is tight, buy a nut to fit it and snug it down against the toilet. It might be difficult to get the nut on the bolt because it has a ragged edge from the cutting, but you can file any barbs sticking out in the hope that the nut can be screwed down. If the bolt is loose, you may have to lift it to see what is going on. The bolts are normally attached to a metal flange set in the concrete. If the bolt is loose, but sticking up through the flange, snugging it down with a nut might work, tightening the bolt against the flange. If the flange is broken, you can buy a flange reinforcer, a half-moon-shaped flange that bolts onto the old flange.

Q. The tank of my new toilet sweats when it is warm outdoors and there is no heat on. How can I prevent that?

R.L., Waltham

A. Have the tank lined with styrene insulation, best done by a plumber. The insulation will keep the water in the tank from cooling off the tank itself, thus preventing the condensation.

Ventilating the bathroom is an easier way. If you have an exhaust fan, use it during and for 30 minutes after a shower. Otherwise, open the windows regularly during the day. Some handy people will run a hot water line to the intake line leading to the tank, mixing with the incoming water and making it warmer.

Two more tricks:

1. Wrap the tank in a terry cloth cover. Funky, but effective.

2. Set a shallow tray under the tank, with the outlet running from the tray into the bowl.

Q. I have an old toilet in my upstairs bathroom, a trusty American Standard that is in good shape. Trouble is, the little ceramic caps to cover the tie-down bolts are missing. Is there anywhere I can find replacements?

BOB HALL, Needham

A. Any plumber usually has a drawer full of them, said two of the handyman's plumbing gurus, Bill Tragakis of Watertown Plumbing Supply and Rich Trethewey, the plumber of ``This Old House.'' The caps might be plastic instead of ceramic, but plumbers have them, or you can buy some at a plumbing shop.

And, to keep the caps from falling off the bolts, secure them with a dab of construction adhesive or adhesive caulk.

Q. I replaced the flapper on my toilet tank and it seems to work OK, but now I have to hold the handle down to make the toilet flush. What can I do? Also, I have a small leak from tank to bowl. I bent the float ball down with the idea that the rising water will shut off the intake valve completely. It worked for a while, but the leak started again.

LENORE FENN, Lexington

A. The new flapper is working all right, but when you flush the toilet and the handle pulls up the flapper, the flapper does not go quite to vertical in order to stay open until the toilet completes its flush. In other words, it is leaning slightly in the open position, just enough not to stay put.

So, you should be able to adjust the chain that goes from the handle rod to the flapper. It will take a bit of experimenting but will work.

As for the other leak, it sounds as if the ball cock, is worn and should be replaced. The ball cock is the shutoff valve in the tank that is supposed to be closing as the water reaches the top of the tank, but isn't. One more thing to check: the float ball. If it's full of water, it will not work at all well. If that is the case, and you cannot make any more repairs or adjustments, you may be wise to replace the whole guts in the tank.

Q. I want to get rid of the slider on our tub shower and replace it with a curtain, but my husband doesn't, because he says water from the curtain will run down outside and cause tiles to heave. What do you say, handyman?

B.R., Westborough

Aa. I say thanks a lot for putting the innocent handyman between husband and wife. But seriously, folks, I'm with B.R., because a curtain is inside the tub when people shower, and stays inside until it dries off, so any dripping water will go into the tub. Besides, curtains are more attractive than sliders and can be inexpensively replaced when necessry.

Q. I am putting down new ceramic tile on my bathroom floor. Rather than take up the toilet, tiling and resetting the toilet, I would like to tile up to the toilet, which has a rectangular base. Would that work?

L.D., Bedford, Mass.

A. It would work, but it will look like it's jury-rigged. Don't do it. I don't think it is illegal, but if you do it, you are creating an extra joint on the floor, similar to the joint beween tub and tile, and you know what a pain that joint is. When you put different materials together in a grouted joint, the grout does not last very long and it is generally not satisfactory.

Q. Help, mildew is eating my bathroom! I washed the wall with bleach and water, then papered the wall. Then, mildew grew under the paper. I took it off, washed the wall again with the bleach solution, and put up new paper. The mildew occurred again, under the paper. Did I do something wrong? Was there mildew in the paste or on the back of the paper? Or what?

MARILYN DAVIDSON, Medford

A. Wow! You did everything right, and came up wrong. There might have been mildew spores lurking in the paste, but most pastes contain a mildewcide to prevent such an occurrence, or recurrence. It's a guess, but I think that the mildew is growing under the paint, if the wall is painted, or behind the plaster or plasterboard wall, and spreading right through the paint, plaster or plasterboard, which can happen.

The cure is drastic: If the wall is painted, remove the paint with chemical paint remover, then treat the wall with bleach and water. If the wall is not painted, remove the plaster or plasterboard and check the cavity behind; it may be damp, encouraging the mildew, which can grow in any warm, damp situation. If the cavity is damp, let it dry out before putting up new plasterboard. Damp cavities can occur next to outside, uninsulated walls.

Q. My bathroom is completely clad in a Masonite wallboard, very smooth and shiny, with plastic covers on the seams. My wife wants to change it, but I am reluctant to rip it off and start all over again. How can it be changed?

D.W., Laconia

A. Those plastic seam covers are a problem, but you could paint the whole thing if you sand the finish very heavily to roughen it and reduce gloss, so the paint will stick. Then paint it with a latex enamel undercoater and finish with any kind of latex wall paint. The seam covers will still show.

A better idea, I think, is to paper the walls. Pull out those seam covers; they should pry out, or you can cut them out. Sand heavily, so the paper will stick. Fill the seams with three successive applications of joint compound, and sand smooth. Apply glue sizing to the walls, then put up the paper; a Wall-Tex type paper (vinyl coated canvas) is best here.

One variation: Instead of trying to fill the seams with joint compound, you can apply a cover-all type paper that will span those seams. Wallpaper shops carry such coverings. Finish with a more decorative paper. You still have to sand heavily and apply glue sizing.

As a handyman, I would find it easier to rip everything out and put up Blueboard or some other type of plasterboard and finish the walls.

Q. My husband wants to put marble tile on a bathroom floor, but I say it's too slippery. Who's right?

KATHY WESALOWSKI, Norfolk

A. Here's the handyman's perilous position again, between husband and wife. But this is one time the handyman doesn't have to take sides because both parties are wrong. Marble tile is no more slippery than glazed ceramic tile. But that's not the reason not to use it. Marble is notoriously absorbent, and will stain if you look at it. And those stains are almost impossible to get out. You coud seal the marble with a sealer, but you would have to do this regularly. So why bother?

You could lay down granite tile, which is just as handsome as marble, but is very dense and therefore resistant to stains but just as slippery as marble. A better plan is to install ceramic tile that is glazed with a slip-resistant glazing. And the smaller the tiles, the more grout lines you will have, and these grout lines will help reduce any slipperiness.

Q. I've taken the door off a tiled shower stall and plan to put a curtain in its place. How can I get the tracks off the tile? It looks as if the tracks were secured with grout, a hard, white material. There are screw holes in the track but no screws, which leads me to believe that the screws were removed, leaving holes in the tile. How can I fill the holes?

L.L., Belmont

A. The tracks were probably screwed on and secured with grout. First, wet down the grout to try to soften it. Get the shower water to play on the grout for a while. This may or may not soften the grout. Whether it does or not, tap a chisel between the track and tile, chipping away at the grout. Then try to pop off the track with the chisel and light hammer blows; it should come free. Once it's off, soften the grout with more water and scrape if off with a wood spatula. Keep wiping with a wet sponge.

Fill the holes with sandless grout (sold in hardware and building supply stores). Touch up with appliance enamel to match the tile. You won't get a match, but you can come close. Install the curtain on a friction-fit rod, and you've got a brand new stall that will look a lot better than when it had a door.

Q. I replaced an old wall-hung toilet with a free-standing one. Now there are holes in the tile where the old tank hung. How can I fill those holes? I found something called Porce-a-Fix, an enamel, but that won't fill the holes.

J.B., Arlington

A. Fill the holes with spackling compound or joint compound, or best, a sandless grout. After that sets, touch up the patches with the Porce-a-Fix, or any appliance enamel of the right color. The shine will be different, but it will even out over time.

Q. I had an acrylic bathtub liner installed 13 years ago, and now it has yellow streaks running down the middle, and a lot of tiny cracks. I'm wondering if I made a mistake, and should have had the tub reglazed instead of using the shell.

MARJORIE BONNELL, Boston

A. I don't think it was a mistake, because I think the liner is a better technique than reglazing. And, 13 years is a pretty long time for a piece of plastic to stand up. There is little you can do about the tiny scratches, but if they are not leaking, there is nothing you have to do. It is unlikely that you will ever detect a leak, anyway. Clean the yellow streaks this way: Wet the area with hydrogen peroxide, and sprinkle cream of tartar on the wet areea. Leave an hour or so, then scrub and rinse.

Of course, if you can contact the original installer, you might get some ideas from him. And, one more idea: Contact a fiberglass repair service such as Mirror Bond. While these companies work with fiberglass (and acrylic is not fiberglass), they might be able to help or tell you where to get help.

Q. I can almost remember your recipe for cleaning a bathtub and tile; I know it contains hydrogen peroxide and cream of tartar. What is the third ingredient?

G.R., Winchester

A. Time and elbow grease are the third and fourth ingredients. Here is how it works, and it works better on a horizontal bathtub than a vertical tile wall: Wet the tub with hydrogen peroxide, then sprinkle lots of cream of tartar on the wet surface. Leave it for an hour or so, then scrub and rinse.

You may be amazed at how clean the tub will get. The Handyman, despairing of a dirty, soiled, stained tub -- so bad he thought he'd have to replace or reglaze it -- used this treatment and, presto, it came clean. And, with routine washing, it has stayed that way 30 years. This treatment works if the tub is dull (the glaze has been rubbed dull after years of vicious work with Ajax and Comet). It won't restore the shine, but my goodness, it will be clean, and will look it. It will also work on fiberglass or any other kind of tub.

As for tiles, try this: Make a paste of hydrogen peroxide and cream of tartar, and smear it on the tile so it will stick a while. After an hour, scrub and rinse. An easier way is to use Soft Scrub, smearing it on and leaving it for a while, or paint thinner. When using the latter, be sure also to ventilate the room.

Q. Can I paint a fiberglass tub? I'd like to do just the outside.

ELIZABETH MONROE, Yarmouthport

A. Yes. Sand lightly to reduce gloss and roughen the finish, and apply one or two coats of latex wall paint. Or, a fiberglass paint, sold in boat shops. Do nothing but the outside; there is very little that will do well on the inside of a tub.

Q. My bathroom door opens in, rather than out. It has been that way for 40 years. Can I reverse it to make it open out? Right now as it opens in, it opens against a blank wall, and really does not interfere with anything. The door is set in a metal frame.

B.B., Peabody

A. That metal frame makes the door virtually impossible to change, because the whole frame would have to be removed, and a new one put in its place; I don't think you could reverse the current metal frame. If it were a wood frame, all you'd have to do is change the sidestop, plus, of course, the door, a lot easier project.

But since it is not a wood frame, why bother? The door now opens against a blank wall, so there is no interference with any appliances.

It's interesting, though; the Handyman has two bathrooms, one with an in-opening door, the other with an out-opening door.

In each case, the door was hung that way for convenience and ease of operation.

Q. I don't have the new turbo toilets, but every time we flush or turn water off in sinks and bathtubs we hear a clunk. It is very annoying. Do you have an answer for this? I've had the plumber in, but it has not yet been fixed.

E. WHITLEY, North Carolina

A. The handyman has an answer for everything, right or wrong. For your clunk, there is an answer, and there may be a fix. The clunk is water hammer, not only annoying but it can break the pipe at a joint. The noise is caused by kinetic energy from the sudden stoppage of water, especially where it turns a corner in the pipe. A possible cure, if you have very high pressure, is to put a pressure-reducing valve on the main water entry.

Another possible cure is to put a water-hammer arrester on the lines leading to the toilet and to the sinks in question. You can buy water-hammer arresters at plumbing supply shops. They are small devices, a little like a ball of air, that are soldered onto the pipe; when the water stops quickly in the pipes, it will fill that air ball, which acts as a cushion in the water line. One is required for each pipe feeding a faucet, at least feeding the faucets that are causing the clunk.

The old-fashioned water-hammer arrester was a 2-foot vertical pipe attached to a horizontal pipe. It contained air, which acted as the cushion, and was effective but difficult to install because of the length. Modern arresters have the advantage of being compact.

Q. How can I remove the non-slip decals on the bottom of a bathtub?

J.M., West Roxbury

A. Ah, it's one of the first things the Handyman learned in his question-answering career, so the cure has been around a while. Fill the tub with an inch of water. Add half a cup of Mr. Clean or other strong liquid detergent. Wait an hour or so; the decals may rise to the surface. If not, give them a nudge with a wooden spatula or similar wooden scraper. Drain the tub and remove the residue under the decals with acetone. Do not use acetone on a fiberglass tub; it will not harm porcelain-enameled cast iron.

Q. I noticed a crack on the toilet bowl where it curves. It does not leak, and I can't fit a fingernail in it. Should I replace the toilet?

N.D., West Roxbury

A. No! Never! That crack is not a crack but is a scratch. If it is inside the bowl, pour a cup of bleach in and leave it for a while. Dirt and other pollutants have colored the scratch; the bleach will make it disappear. If it is on the outside of the bowl, you can touch it up with bleach or ignore it. If it inside the bowl, I'll bet someone got carried away with a bowl brush, which has a wire frame.

Q. I just moved into an apartment that has a shower stall with 12 inches of wall space between the top of the stall and ceiling. That wall space has a peeling paint problem. Can I put vinyl tiles on that wall?

J.S., Stoneham

A. Absolutely, and the landlord should be thankful that you corrected a longstanding problem. Use the peel-and-stick self-adhesive tiles. The 12-by 12-inch tiles will fit right in the space. Be sure to scrape and sand off any peeling paint before you stick on the tiles.

Q. My daughter's house has 1.6-gallon low flow toilets that don't always work well. I was thinking of getting the new low-flow turbo toilets instead. Will they work well?

B.B., Framingham

A. The new turbo toilets do work well, but oh my, are some of them ever noisy, shutting off with a real clunk! One type, called Flushmate, pressurizes the water flow, and is sold by Watertown Plumbing Supply.

Many low-flow toilets are, indeed, balky sometimes, and the handyman feels that every low-flow toilet (except the turbo types) should be sold with a plumbers' helper, a rubber plunger that will quickly clear clogs in such toilets.

The handyman has a low-flow toilet (one out of two ain't bad) and happens to like it; plunging out a clog is easy, and a small price to pay for using so much less expensive water. It's interesting: Low-flow toilet tanks contain 5 or more gallons of water, which seems to defeat the purpose of low flow.

But wait; only 1.6 gallons are used in each flush. The purpose of the 5 or more gallons is that piled on top of the 1.6 gallons, their weight gives the 1.6 gallons more power, but the tank cuts off the flow after 1.6 gallons.

One more point; if you have to flush a low-flow two or three times, you are still using less water (3.2 to 4.8 gallons) than one flush of a 5-gallon toilet.

Q. My house is 20 years old. Cracks are appearing in my bathroom marble sink, around the drain, and are getting worse. How can I keep them from getting worse?

PAT PECHO, Charlotte, N.C.

A. Real marble is unlikely to do that, so I think what you mean by marble is cultured marble or a Corian-type polymer. There is no fix for this if it is real marble or cultured marble. The cracks are caused by the drain pipe being fitted too tightly. Have the connection loosened a bit, and while this won't fix the cracks, it may prevent further cracking.

If it is Corian, you might be able to have the cracks filled. Check with the Corian people, because in one case that I know of in which cracks appeared around the drain Corian replaced the sink free.

Q. I am renovating a bathroom, and plan to put in a new tub. Trouble is, the old tub measures only 29 inches from edge to wall, and new tubs are 32 inches wide. I can't put in a wider tub because the old one already is overlapping part of a door frame. What can I do? I plan to take out the old tile and everything, and put in all new fixtures.

BARBARA CHOLAKOS, Arlington

A. That old tub is wider than you think. The edge of the tub next to the wall is under the wall finish (tile, old plaster or plasterboard and possibly some kind of lath). This might total 2 inches, possibly 3. To find out, take off some of the tiles and everything else down to the bare studs. If you do this near the tub edge, you will see the tub edge, which has a flange on it, and that should be up against the studs. Measure the old tub from this flange to the opposite edge to get the true width, which, if you are lucky, will be 32 inches.

If not, consider leaving the tub in place and putting an acrylic shell over it. This is good if you are changing the tub just for the color.

If the old tub is butting up against the wall surface and not against the tub, you might be able to find the space for the new tub by removing all wall finish and butting the new tub against the studs. The new wall finish would come down to the new tub, not behind it.

Q. I am putting in a bathroom medicine cabinet that I want to span three studs, so I have to cut off the middle stud. The wall is not bearing. Should I put in a header?

B.S., Natick, Mass.

A. It would be a good idea to put in a header, a horizontal 2-by-4 or whatever size fits. And a sill at the bottom of the opening, as well. But since the wall is not bearing, you could use the frame of the cabinet as header and sill, if that frame is at least three-quarters of an inch thick, instead of a separate header and sill. Or a separate header can be a 1-by (a three-quarter-inch-thick board) instead of a 2-by (a 2-by-4). The main reason for a header in this case is to have something in which to nail the frame of the cabinet.

Q. I plan to install a vinyl tub surround, over and above my cast-iron tub. Can I put it right over the wall tiles?

RAYMOND McLAUHGLIN, Chelmsford

A. Yes, indeed. You can glue it right on, with construction adhesive or whatever is recommended by the seller of the tub surround.

Q. The joint between the tub and tile at the drain end of my tub is 1/2 inch. Would grout still work in such a wide joint, or would caulking be better?

DAVID HARTZ, Charlotte, N.C.

A. The widest space recommended for grout is 1/4 inch. Your 1/2-inch joint may be too much for grout and even for caulking, because the depth of the joint is only about 1/4 inch.

But here is what I suggest, unless you have tried it without success: Use a sanded grout (grout that has sand in it), apply it very compactly and smooth it off. Let it set, apply a tile sealer and see what happens. Even in a joint that wide, I think grout is better than caulking. And be sure to chip and gouge out all the old grout or caulking; this will give the new grout a better chance of staying where it belongs.

Here's another idea: If the tiles along the drain end of the tub were cut, try this: Remove them (if they are glued on), applying heat to loosen them and cut new tiles so that the joint will be a maximum of 1/8 inch. If the tiles were not cut, then there is not much you can do but grout the joint and hope for the best.

There are rigid plastic coves, self-adhesive lengths that you can put over the joint, but even these might not cover the 1/2-inch gap.

Q. I have a mildew problem that bleach won't cure. The envelope-licking sponge I use has gotten mildewy, and bleach destroys the sponge. I tried rubbing alcohol without success. Is there anything that might work?

GEORGE PAPPAS, Nashua, N.H.

A. Hmm, another poser. Try the non-chlorine bleach. Or, a solution of trisodium phosphate (TSP cleaner). Rinse thoroughly.

I was just wondering. The sponge may be cellulose, which makes it sensitive to bleach. So, try this: Buy a natural sponge and treat it with the typical mildew-busting solution of 1 part liquid chlorine bleach and 3 parts water. If it eats the sponge, then my idea won't work. But if it doesn't, cut the sponge to size and replace the moistening sponge with it. Then you can use the bleach solution to kill the mildew.

Q. I am getting moisture in my tub-shower area that just won't go away, because of an 18-inch ``wall'' that hangs down from the ceiling, separating the tub-shower area from the bathroom. An exhaust fan in the middle of the bathroom ceiling does little to remove the moisture from the shower area ceiling, where it is trapped by that hanging wall. How can I get rid of that moisture?

FRANK SPARROW, Boston

A. Anything for design. Some benighted designer thought it would be nice to provide such a hanging wall to separate the tub-shower area. Clever but impractical; that divider creates a pocket for moisture to collect and stay forever. The designer and his ilk never paid any attention to the problems it could cause.

But there is something you can do about it. Take the finish off the divider, revealing the studs; you should be able to remove the vertical studs, leaving the horizontal top plate and bottom plate in place; that divider doesn't hold anything up except itself. You could cover those exposed plates with a decorative screen on each side for a finished look, allowing moist air to escape.

Or, do as the handyman did in his own bathroom when he put in an oversize shower stall: Install 3/4- or 1-inch dowels a few inches apart. This will look nice and let the moist air escape.

Or, take down the whole divider and finish off the ceiling where the horizontal top plate was.

Q. The rim holes of my toilet get caked with mineral, reducing the flushing quality. I have opened them with a coat hanger and Lime-Aawy, with only temporary relief. How can I keep those holes open?

D.D., Wellesley

A. Keep opening the holes. There is little you can do because the hard water builds up the minerals; and because the rim holes are small, they cake up more quickly. Putting in a whole-house water softener might help. Replacing the toilet might be a better solution, especially if the rim holes in the new toilet are bigger.

When P.K. of Brookline asked about keeping a toilet set on a concrete floor (with a missing nut) from wobbling, the Handyman suggested trying to snug it down with a new nut, if the bolt is secure in the metal flange under the toilet, and if the flange is not loose. Sometimes the flange is broken, but a flange reinforcer, a half-moon-shaped flange that bolts onto the old flange, is available from plumbers.

Elmer Pinkerton of Elmwood, Neb., took great issue with this answer, assuming that the concrete floor is uneven, and said any repair could break the bowl. He suggested putting wood shims under the toilet to create an even base, so the toilet would sit evenly, then snugging down the nut on the bolt.

Good point, but it is based on the assumption that the concrete floor is uneven, but either answer is valid. At least P.K. of Brookline has a choice of what to do.

Q. I just had the insides of a toilet installed, and it simply works too well. The flapper is almost impossible to pull up with the flush lever; in fact I can't move the lever. How can I make it work right?

R.C., Natick

A. The flapper mechanism may be out of adjustment, pressing down on the drain opening so tightly that it just won't release itself when required. It may be mechanical, which should make it fairly easy to make the adjustment yourself, but that may be more difficult with a new mechanism than it was with the old. So, if experimenting with adjustment doesn't work, a plumber could probably fix it in a hurry, for a fee, but after all, you are paying for his expertise. If the plumber can't make an adjustment, then it may need replacing.

Q. I have a crack in the top cover of my toilet tank. Do I need to replace it? What if the tank itself is cracked?

HELEN GREGOIRE, Stoneham

A. You don't have to replace the cover, which is only decorative. If the cover is not in two pieces, there is no need for replacement. Besides, covers are not available individually that I know of. You might be able to find one at a house salvage company, but then the problem is getting one to fit.

If the tank itself is cracked, and not leaking, there is also no need to replace it, until it starts leaking. If it is leaking, you might be able to make a repair. Empty the tank and let it dry off, then press plumber's epoxy into and on the crack and let it set. Refill the tank and hope for the best.

If the tank continues to leak, you will have to put in a new toilet.

Q. I plan to put a bathroom in my basement. Someone said I will need an injection toilet because the sewer line is too high, in order to pump the drain into the higher line. The line is actually about 4 inches above the floor. Will an injection toilet be needed?

J.S., Dorchester

A. Probably. A plumber can provide one readily. You may need an injection pump for the sink or shower or tub drains as well. One way of possibly avoiding this is to build the floor higher than the sewer line, if you have enough ceiling height, and to let drains operate in the normal manner, by gravity.

Q. An old problem cropped up again. My first-floor toilet tank sweats, mostly on the bottom, but it is dripping on the floor and could cause decay. I bought a tank liner at Spag's in Shrewsbury for the second-floor toilet, and there is less sweating. Would a liner help for the first-floor toilet? We are on well water and it's mighty cold.

ALYCE LUIPPOLD, Westborough

A. A liner will definitely help, but make sure you line the bottom of the tank as well as the sides.

Another trick you can try is to divert a little hot water into the intake line feeding the tank. This will keep the tank water warmer, reducing condensation. And, this additional warm water will help reduce condensation that may be occurring on the toilet bowl, as well. That seems to be the only cure for bowl sweating.

A couple of extra ideas for the tank, however: One is to put a tray under the tank with a hose leading to the toilet. You won't stop the sweating, but the water will drip into the pan and into the toilet. And finally, I think they still sell terry-cloth jackets for tanks that will keep the tank warmer, a little like a tea cozy.

Q. I have a window in the tub area of my bathroom. I hate plastic curtains, which seem to be the only solution for keeping that window from getting soaked during showers. Is there any other solution that would work?

KEITH DINSMOOR, Braintree

A. There are certainly solutions, but not necessarily ones that would work for you. But what the heck, here they are:

1. Take out the window and wall in the opening. Properly done, this walling in is invisible. But it will work only if you install an exhaust fan venting to the outdoors.

2. Take out the windows and put in one with glass blocks. It will provide light and be watertight, but this installation would also require an exhaust fan.

3. Paint the window and frame with Zinsser's Perma-White Mildew-Proof bathroom paint. It claims to resist mildew for up to five years and to go over virtually any old painted surface.

4. Despite your aversion to plastic curtains, consider a new one anyway. The new shower curtains and matched window curtains are quite soft and remain that way; they can be quite attractive, some with patterns, and are not the old-fasioned plastic that gets stiff and unmanageable with age.

Q. I am having an awful time getting soap off the shower walls. It streams right down the tile and makes a mess. I tried turpentine and lacquer thinner; the thinner helped a little. Is there any sure-fire way to get rid of the soap?

JOHN NUGENT, Winthrop

A. If the lacquer thinner helped a little, then apply more. This is a rare example of ``more is better.'' Be extremely careful with lacquer thinner; it is highly volatile. Use plenty of ventilation when working with this material. Paint thinner also should work. But in any case, whatever you use, let it sit on the soap as long as practicable; the solvent must dissolve the soap before you can rub it off with a dry cloth.

Q. My toilet sometimes flushes all by itself. How in the world can that happen and what can I do about it?

EDWARD SCHLAICH, Lexington

A. We've heard of haunted houses, but haunted toilets? Come on! Maybe you can get it to perform on Saturday night. But seriously, it does happen, so it is probably not a poltergeist. Here's the story: After a flush, the flapper or rubber ball in the tank does not seat properly on the drain opening to the bowl. A slow leak occurs, which, if it gets fast enough, can raise the flapper and flush the toilet.

One cure is to adjust that flapper or ball so that it sits directly on the opening, creating a watertight seal. Some flapper/ball units are easily adjusted, others are not and may require a plumber, who may recommend installing new ``guts'' in the tank.

To determine that a leak is the cause, put a little vegetable dye in the tank and check the bowl to see if that dyed water is leaking into the bowl. If that is happening, then you go to Plan A above. If it isn't happening . . . call Ghostbusters.

Q. I plan to put a bathroom in my basement. Someone said I will need an injection toilet because the sewer line is too high, in order to pump the drain into the higher line. The line is actually about 4 inches above the floor. Will an injection toilet be needed?

J.S., Dorchester

A. Probably. A plumber can provide one readily. You may need an injection pump for the sink or shower or tub drains as well. One way of possibly avoiding this is to build the floor higher than the sewer line, if you have enough ceiling height, and to let drains operate in the normal manner, by gravity. A plumber could tell you if this is feasible.