If you have neither, and have grand plans for making the back yard an extra room for the summer, what do you choose?

Both have their assets and debits, so you could compromise and spend twice as much money and put in both.

Well, maybe, but there is still the question of which is best -- for you.

So let's find out what is best for you.

It is made of wood, and therefore can be raised high enough to make it an easy walk from back door to deck. It also makes it easier to bring dinner and other goodies to the awaiting hungry mob.

Railings can be added, giving the deck the feeling of an actual room. In fact, if the deck is just a few feet off the ground, railings are required.

The deck can be converted to a screened porch.

While a wood deck must be maintained (cleaned, sealed, or stained on a regular basis) the maintenance is relatively easy. Mildew and algae (the familiar black and green spots, respectively) can be washed off with some ease with bleach and water.

You have a choice of woods. If you don't like the idea of pressure-treated wood, use cedar, fir, mahogany, or some of the new composite wood such as Trex, or an all-vinyl floor. These suggestions are for the floor, not the superstructure, which can be fir or pressure-treated lumber.

A deck floor is made of spaced boards, so there is never a question of drainage or lack of it; there are no standing puddles in bad weather, or waiting for a puddle to dry out after it rains. In other words, there is little waiting needed after the rain stops.

Disadvantages: A wood deck is expensive, especially if you have it done by a pro. In fact, it is relatively expensive even if you do the work yourself.

Although maintenance was listed as an advantage, the need for maintenance is a disadvantage to the owner who doesn't want any maintenance at all.

Wood may be slippery when wet.

Advantages of a patio:

Good looks. There is nothing quite like a brick patio, sidewalk, or any other space for tradition and convenience, not to mention good looks again.

You can locate a patio anywhere: near the house, under a tree, even on two levels to compensate for uneven land.

No maintenance. Once the bricks are installed on sand or stone dust, there is no need to keep them clean because Nature will do that for you. As with a wood deck, mildew and/or algae can be cleaned off a patio with bleach and water. But as with a patio, it doesn't hurt to keep the mildew and/or algae, unless it becomes intolerable.

A patio can be done by an amateur: you. Laying the brick is simple, but the work itself is heavy duty.

A patio is relatively inexpensive; brick costs about $2.50 a square foot, with extra cost for sand or stone dust.

Disadvantages of a patio: On the ground, it is lower than the house floor, so getting to it is not always convenient, especially when you're loaded down with steaks or other goodies for the barbecue.

It takes a lot of work to build a patio.

Bricks get dirty and dull outdoors, and cleaning them is difficult. While we said there is no maintenance with a patio, some owners would find any dirt, mildew, and/or algae intolerable.

OK, so you opt for a brick patio, brick set in a bed of sand or stone dust, and you will do it yourself. Here are a few ideas that can carry you through to completion.

If your patio is in the sun, or it is sunny most of the day, it would be a good idea to put agricultural cloth or perforated black plastic on the bed of sand to help prevent weeds from coing up between the bricks, but allow water to drain. If the weeds do come, treat them with vinegar; you will be weed-free for the rest of the season.

Such underlayments are less necessary if the patio is shaded most or all of the day.

You need five bricks per square foot. To figure how many bricks you need, determine the size of the patio; say it is 100 square feet. Multiply this figure by five and you get 500 bricks.

To make the patio flush with the ground, excavate the desired area to a depth of 4 1/2 to 5 inches. You need only about 2 inches of sand or stone dust as a bed for the brick, so that plus the 2 1/4-inch thickness of the brick will bring the brick up to the desired level.

If tree roots and other obstacles make it difficult to excavate, then don't; you can instead raise the patio above ground, by spreading stone dust or sand directly on the ground: two or three inches is enough.

Whether the patio is flush with the ground or raised above it, you need a border to keep the loose bricks from walking or spreading. Bricks in sand or stone dust are always laid dry, without mortar.

A good border unit is a soldier brick, the same City Hall Paver laid on its long end. Another good unit is a concrete patio block, 16 inches long, 8 inches wide, and 2 inches thick. These can be laid on their long or short side.

Landscape timbers are also good as a border. Specify pressure-treated timbers.

While stone dust is good as a base, sand is better to sprinkle between the tightly-packed bricks because it has fewer pebbles than stone dust.

Now the fun starts: Laying the bricks. There are several patterns you can create from bricks, but the easiest, and the best in the long run, is a running or common bond, in which the bricks in the first row overlap the bricks in the second by half their length.

Set the bricks tightly against each other. When the job is done, sweep sand between them. It will take quite a bit of sand to get into the joints, but once it is in place, the bricks are held tightly in position.

As you set each brick, tap it with the handle of a heavy mallet, or use a plastic- or rubber-headed mallet to position the brick at the right level. If the brick goes too deeply, add some stone dust under it. If the brick doesn't want to snuggle in, take a bit of the stone dust out.

Use the 2 x 4 as a level checker along the length of the bricks as well as across their width.

You can slope the patio a bit, especially where it is next to the house foundation, to allow drainage and prevent pileup of water along the foundation. Where the patio is not near the house, you can make it level, because water will drain right through the joints and stone dust and into the ground.

The procedure is simple; that is, uncomplicated, but the work is hard. At the end of the day, you will be well aware of your muscles, because all will be a bit sore.

But after a good night's rest, you'll be rarin' to go to finish the job. Maybe.

One more asset for a brick patio. You don't have to mow the darned thing.