Q: We have an old wood deck we are thinking of replacing. We considered using a composite material instead of wood, but research has made us doubtful. Can you give us some background about composite deck materials?

A: Composite materials, made from a mixture of wood particles and plastic, are quite popular and considered a premium material for decks because they resist splintering, cracking and rot and do not contain possibly harmful wood preservatives. But there are some misunderstandings about composites, which are sold under a number of brands.

Composites are not maintenance-free. They need periodic cleaning to remove dirt and stains such as mildew. However, they do not need treatment with water repellents or stains as wood decks do. Some composites have locked-in colors.

Composites are not as structurally strong as conventional deck wood. This is why the supporting structure of a deck is usually made of pressure-treated wood, generally southern yellow pine. The composite material is used for the decking, or floor, rails and trim. If the supporting structure is properly built, composites are considered strong enough for those purposes.

Composites cost considerably more than wood. Many consumers feel the advantages, including reduced maintenance and improved appearance, make the extra cost well worth it.

A dozen brands of composites are rated in the July 2008 issue of Consumer Reports magazine, on sale at many bookstores and newsstands and available at some public libraries. The ratings cover such points as color change, sagging and mildew resistance.

Q: One of our toilets, which is about 31 years old, has developed a 10-inch hairline crack in the bowl. It doesn't seem to be leaking. Can I repair this or do I need a new toilet?

A: I think you definitely need a new toilet. I know of no practical way to repair a cracked toilet bowl or toilet tank, and I personally would not take a chance on a repair. If a toilet bowl or tank bursts, it can cause extensive water damage.

New toilets use much less water per flush than the old-timers, so you can save some money on your water bill. To ensure good flushing, look for a so-called high-performance toilet with a larger trap and flush openings.

Q: We have an older house with stone basement walls that are coated on the inside with cement mortar. We have been trying to dig off some mortar that has crumbled and replace it with fresh mortar, but the mortar just falls off the wall when we try to apply it. Can you help?

A: It could be that the mortar is not a good consistency for sticking to a vertical surface. If it is too dry, it will fall off and if too wet, it will "slump" or thicken at the bottom of the wall. Try mixing a batch that clings to your trowel when you hold it vertically. Put some of this mixture on a flat board and hold it close to or against the wall, then push mortar to the wall and flatten it to the thickness you want. Wetting the surface being mortared will sometimes improve adhesion.