DMITRI HOMSY, Canton

A. From what the engineer suggests, your house is defective and the builder should be brought to task. I would get a second opinion concerning the foundation. There is another possible cause of the cracks in addition to settling and stress, not necessarily due to a faulty foundation. A large room with cathedral ceiling open end to end is not always stable, and is subject to excessive stress.

So, consider installing collar ties to connect the two slopes of the cathedral ceiling. Collar tiles are commonly found in attics under a gabled roof; the rafters form an upside-down ``V,'' and the collar ties turn that upside-down ``V'' into an ``A.'' If you feel that collar ties will spoil the aesthetics, then live with the cracks.

Finally, you can fill the cracks with caulking: Press it in with your fingers, smooth off and paint, if necessary. The caulking will expand and contract with the movement of the ceiling, and should stay in the cracks.

Q. My house is next to a ravine. The adjacent garage has settled a bit, and the previous owner jacked up the garage and put footings under the foundation. The garage is settling again. What can I do?

P.L., West Falmouth

A. With that nearby ravine, the situation is aggravated. I think your only recourse is to contact an engineer or contractor experienced in foundations. It sounds too iffy to try to do anything yourself, although the engineer or contractor could tell you what needs to be done.

Q. I have a vertical crack in my concrete foundation. How can I fix it?

JOSEPH POWERS, South Peabody

A. If it is not leaking water, it does not have to be fixed. If it is a hairline cradck, it also does not have to be fixed. If it is a little wider, you can fill it with caulking compound. If it is half an inch wide or wider, you can fill it with hydraulic cement, and try to get the cement as deeply into the crack as possible. All these fixes are cosmetic.

If the crack is leaking water, it is best fixed from the outside, which means you have to excavate outdoors to expose it. Then chip it out to perhaps 3/4 inch wide and install hydraulic cement. Then apply roofing cement several inches wide over the crack, embed roofing felt over it, and add more roofing cement before back-filling.

Q. I live in a double-wide mobile home, 60 by 28 feet, which is set on concrete blocks as a foundation. I am concerned that there is inefficient ventilation inside that foundation, and I hear noises in the house, little popping sounds, not too loud but they can be heard. There are vents in the foundation that open at 70 degrees or higher, and I found that it is dry as a bone under the house. Is there anything I should do?

KEN DOWNEY, Skowhegan, Maine

A. Yes, there is. Sit back and relax and enjoy your house. The fact that it is bone dry under the house means that the vents are working, and will stay open in the summer and close in the winter, which is the way vents are supposed to work, and that there are enough of them to release water vapor. The expanding and contracting of the vinyl siding, caused by temperature changes, are making those popping sounds. They are harmless, so live with them. If the siding were aluminum, the popping would be louder. If you get excessive moisture in the house itself in winter, simply ventilate daily by opening windows for a few minutes twice a day.

Q. I am painting my fieldstone foundation in the basement. A mason said I could use any latex or oil paint. Would this work?

ANN DORFMAN, Newton

A. Not very well. Instead, apply two thin coats of a solid color latex stain. Thin coats are very important to success, and will work both in the basement and outdoors. Even solid color latex stains can peel (and probably will, sooner or later), but less so than paint. Remember: thin coats! That means applied in thin layers, not thinned down stain.

Q. I plan to put a second story on my ranch house. The 100-year-old foundation is stone. Who can I call to determine if that foundation will take the weight of a second story?

SUZANNE BERRY, Milton

A. A stone foundation that is plumb and level, and big enough, is likely to hold the extra weight, but to make sure check with an engineer or an architect. The contractor you hire to do the work should also be able to tell you, or he will check with an engineer or architect.

Q. A part of the fieldstone foundation of the 1897 house I just bought is bowing out from water damage, and an engineer said that, as such, it does not provide proper support for the first floor. I was told that it would cost $3,500 for a engineer to draw up a plan and tell me what has to be done. Isn't that kind of steep? It sounds as expensive as what has to be done.

M.S., Roxbury

A. It sounds expensive on the face of it, but you have to consider that you are paying for the engineer's expertise, which, it is hoped, is a guarantee that what he suggests will work. I really don't think such a fee is excessive, and I also have a feeling that the work itself will be a lot more. After all, it deals with the structure of the house and the foundation, critical to keeping the house from falling apart.

Q. The living room of my ranch house extends 8 feet beyond the foundation, and is supported by posts at the far end. The resulting crawl space under that extension is very shallow, and has a slab floor, and is a real haven for mice. How can I fill in that space to keep the mice out? The house is only 15 years old.

H.O., Wayland

A. The builder should have filled in that space, or rather built a perimeter wall around it. But this is what you can do: Make a frame of pressure-treated 2-by-4s under the living room and attached to the posts. Nail hardware cloth (half-inch steel mesh) to the frame, then nail on pressure-treated lattice. The hardware cloth will keep out vermin and the lattice will make it all look pretty good. And, you don't have to paint or stain the lattice. If you like color (white, that is), use the new PVC vinyl lattice.

The lattice (pressure-treated or vinyl) is becoming popular as a fill-in finish for such areas, but it is not new; lattice was used extensively to fill in areas below porches. You can see it all the time.

Q. I have a major crack in the foundation of my four-year-old house. It goes from top to bottom of the concrete foundation, and all the way through. I tried filling it with hydraulic cement on the inside without success. Would an asphalt sealer work on the inside?

KARL CIALLI, Westford

A. If the crack is not leaking water, there isn't much you have to do. You could insert hydraulic cement on the inside, but you have to enlarge the crack enough in order to get enough cement in to be effective, and to stay put.

If the crack is leaking, that is another kettle of fish, and asphalt sealer on the inside is not going to stop the leak. The best thing for a leaking crack is to dig down on the outside, enlarge the crack, and insert hydraulic cement. Then apply a layer of roof cement (a tarlike material that does not need heating to do its work), then a layer of roofing felt, and a second layer of roofing cement.

Q. The wall of my poured concrete foundation cracked after a year. It's just a hairline, but I get a little water seepage along the lower 2 to 3 feet, and only in the heaviest rain. There is a perimeter drain around the foundation. I put hydraulic cement in the crack, but it cracked, too. Can I fill that crack with anything?

ED KRUKONIS, Beverly

A. Sometimes several coats of a silicone masonry sealer will fill a narrow crack. I know of one person who filled such a crack in his birdbath, and it worked. But it will take many coats.

Another possibility: Perusing the Improvements catalog recently, I ran across Crack Cure, a sealant that claims to seal hairline cracks that other sealants can't reach. It's item No. 140830 (2 ounces) and No. 142663 (8 ounces). Call 1 (800) 642-2112.

No guarantees, though, because catalog companies claim an awful lot for their products (they want to sell them, of course), so let the buyer beware. Another caveat: Anything you try to seal on the inside is less likely to work than if it were applied to the outside.

The hydraulic cement you used probably did not work because the crack was too narrow to get much of it in. The Crack Cure and silicone masonry sealer have a better chance of filling the crack because they are liquid.

Q. I get too darned much water in my basement; it just flows through the joints of my fieldstone foundation, but only on one side, not the driveway side. What's the easiest way to stop or at least slow down this flow? The land on the bad side is certainly not sloping down away from the house. There are 24 inches of foundation showing between land and siding.

JOHN O'TOOLE, Jamaica Plain

A. Easy way? There are no easy ways, but there are three things you can do, and if you do them yourself, all inexpensive. 1. Point the foundation stone on the inside: chip out old mortar and insert new. 2. Regrade outdoors so the land is sloping, down and away from the house, to allow more runoff. You have plenty of room to do this because of that 24 inches of foundation showing. When regrading, leave at least 8 inches of foundation showing. 3. Install a sump (hole in the cellar floor) and a pump to remove collected water. Make sure the water is pumped at least 10 feet from the house.

Several more things, if you have the time and energy: If you don't have gutters, install some, and make sure the downspouts are draining 10 feet from the house. If you do have gutters, make sure those downspouts are draining away from the house. Or, if you don't have gutters, install instead a concrete apron along the foundation, 6 inches deep and 18-to-24 inches wide, sloping ever so slightly. The apron will prevent quite a bit of roof water from going down the foundation.

Q. What kind of a mix can I use to fill some shallow chipped-out areas of my concrete foundation? There are no leaks.

BERT KESSEL, Lincoln

A. Your best bet is to buy some Top and Bond, a special type of mortar or concrete designed to go on in very thin layers and hold. The Handyman filled some areas in his foundation with Top and Bond last fall; the patch still looks good and is holding.

Q. My fieldstone foundation leaks like a sieve. I can see the holes where water comes in. How can I fill those holes?

L.G., Swampscott

A. Fill the big holes with mortar; and if the hole is quite large, fill it by lining the opening first, letting the mortar set, then filling the smaller hole. Or stick a stone in the fresh mortar, then add more mortar. Medium-size holes might also have to be filled with mortar as well, but small ones, and maybe some medium-size ones, can be filled with hydraulic cement.

Q. There are four large cracks in the foundation in my four-year-old house. They are taller than they are large -- some one-16th-inch to one-eighth-inch inch wide -- and they are wet. Only one is leaking in two places. How can I patch them to keep them from leaking?

M.N., Tyngsborough

A. Ouch! That is tough for a four-year-old house, and it is unlikely the contractor will do anything for free, because the warranty (just a year) is long gone. The only sure way I know of to seal those cracks is to fix them from the outside. Dig outside to expose the cracks from the footing all the way up, apply a wide band of roofing cement, cover with a 6- to 12-inch-wide strip of roofing felt, then more roofing cement before backfilling.

For better protection, it would be good (and a lot more work) to enlarge the crack, insert hydraulic cement, which expands as it sets, and then do the roofing cement and roofing felt patch. While there are products that claim to seal on the inside, the Handyman is skeptical because it is very difficult to prevent water from entering against an inside patch.

Q. My bulkhead foundation and stairs were poured separately from the house, and now I get water seeping through the joint between bulkhead and house foundation. I tried plugging the joint from the inside with cement, but it didn't work. What can I do?

G.N., Boston

A. Plugging the joint from the inside almost never works, even if you enlarge the joint so more cement can be set in. Try it from the outside, but that would require digging down to the footings, a lot of work. And, if you do that, enlarge the joint and install hydraulic cement, which expands as it sets, making a tighter repair. And, while you are at it, after putting in the cement, and letting it set, slather roofing cement in the corner, about 6 inches on each side of the joint, the full height of the joint. Then fold a piece of tarpaper into an ``L'' shape and press it into the roofing cement in the corner. Apply another coat of roofing cement before back-filling.

An alternative you can try is this, and it is a lot less work: Build a dry well at the bottom of the stairs. Cut through the concrete floor and dig a hole about 12 inches deep, fill it halfway with crushed stone and put a grille over it. This dry well will collect any seeping water; you will still get seeping water, but it will not go all over the floor. At least it shouldn't.

Q. My hatchway foundation is slanting a bit, and is made of brick. I built a wood door for it and it lasted a few years before succumbing to kids and wear and tear. What is best to replace it? Wood or metal? I found that the standard Bilco doors are too small, or the wrong shape.

B.M., Stow

A. Another manufacturer of metal doors, Gordon in Southington, Conn., may also make only standard doors, but you can always call, or check out building supply stores, which may carry them.

Another possibility is the clam door, a one-piece fiberglass door that opens like a clam shell, made by Palmer River Products Inc., 97 Broad Common Road, Bristol, RI 02809. The small one is 51 inches wide, 64 inches long; the large is 55 inches wide, 72 inches long.

Or, fiberglass bulkhead doors made by Paramount Industries, PO Box 216, Westport Point, MA 02791, 508-636-8211. Originially they make the doors only with sides; some day, a spokesman said, the company may make just the doors.

Some of the doors are quite expensive, so if the prices don't appeal to you, you may have to go back to a wood door. Use pressure-treated tongued and grooved boards and set them with a Z brace at the back. Use screws, not nails.

A wood door will be quite heavy, so you might want to set up a series of counterweights. Only your imagination will let you do that; I know of no plans.