Question: We just had our chimney cleaned and the gentleman is advising us to have our chimney lined, for which he gave us an estimate of $2,800. How in the world does one know when a chimney needs a liner? Our house is 40 years old. Is that an indicator that it does?

He took a flashlight and showed me a pile of whitish material in the back of the furnace pipe that was about 21/2 inches high. What do you think?

Answer: From what I understand, age of the house may only be one factor in determining whether your chimney needs a liner.

The experts recommend regular cleaning of chimneys for a good reason.

When you delay maintenance, creosote from wood-burning eventually builds up enough to create a fire hazard.

The same thing happens when residue from whatever you heat your house with - probably heating oil - builds up as well.

Many years ago, shortly before Christmas, the pipe connecting the coal-converted-to-oil furnace to the chimney of my old house came unconnected, and there was a pile of a whitish material at the base.

I don't know for sure, but the pipe appeared to be plastered to the base of the chimney, and the whitish material was probably a mixture of plaster and efflorescence - residue created when water in porous material evaporates, leaving salt as a white, fluffy deposit behind.

The "gentleman" should have identified the material and explained what it meant, in any event.

I looked up my chimney and saw no blockage. Later, a chimney contractor checked it out and found that the original terra-cotta masonry lining, by then a century old, was fine and all the brick mortar was intact.

I was fortunate, because a few years before, the owners of the adjacent twin wanted to open up the chimney that vented a coal-burning stove and we shared the $1,000 cost of lining and repairing the mortar.

Most chimney contractors recommend a stainless-steel liner that slips in from the top of the chimney all the way down.

They are recommended for chimneys that are used to vent wood-burning stoves because creosote can quickly mess up other metals.

First, you need more than just one estimate, and here's hoping that you find someone who will offer you a more complete and accurate explanation of your problem, and all the available alternatives - information readily accessible online.

The liner that is used will have to properly fit the inside of the chimney.

Many years back, a colleague had a liner installed in the chimney when he converted his furnace from oil to gas. All the houses in his neighborhood had chimneys with an unusual bend that required considerable finessing by the contractor.

Now, to the cost. Mark Wade, the Center City real estate agent who deals with a lot of people who buy places with fireplaces in need of working chimneys, and who has done some renovation projects himself, said he's never heard less than $4,000.

Recently, I was in South Philadelphia, chatting with Franco Borda, the owner of FrancoLuigi's Pizzeria and the High Note Cafe, and public relations guru George Polgar.

When I asked if either had that work done recently, both said yes - about $2,500 to $3,000 - but Polgar had some mortar replacement work as well.

Again, you need a complete and written explanation of the problem and more than one estimate before you consider having the work done.

A staining tip. For those of you looking for stains that are short on volatile organic compounds but high on performance, I recommend Minwax Express Color, which you wipe onto whatever you are staining.

It is water-based, cleans up easily, and most of all, doesn't need to spend weeks off-gassing in your workshop.

Price: $8 at home centers.