Improved Appearance : Flagstones Make Nice New Surface for Patio
Millions of houses across the country have patios that consist solely of concrete slabs several inches thick. Many of them are cracked or otherwise in need of repair, but regardless of their condition, they can be given new lives and improved appearances by being made into flagstone patios.
This can be accomplished by installing the flagstones in a bed of mortar. The best part about making any necessary patches in the original concrete slab is that you need not worry how the finished job looks. In fact, you do not have to trowel and smooth the surfaces, since the rougher they are the better they are for the project that is to come.
The mortar into which the flagstones will be placed will grip better on surfaces that have not been troweled level. Speaking of level, your patio should be sloped slightly so that rainwater runs away from the house. The slopes need not be more than one inch for every 10 feet, although some authorities favor more of a pitch than that.
Just as you should arrange a couple of rows of resilient tiles on a house floor before putting down any adhesive, do the same with the flagstones. This will give you an idea of how they will fit, whether they look better one way or another and what can be done to minimize the amount of cutting.
Not Too Watery
The mortar mixture should be one part portland cement and three parts of sand. When you do the mixing or even if you should use the pre-mixed kind, do not let the mixture get too watery. The flagstones must be set into a mortar that is fairly stiff, being certain that each flagstone is clean.
You should do only a couple of flagstones at a time, otherwise the mortar will begin to set up before you get to it. Spread the mortar about one inch thick. As is recommended in “Basic Masonry Techniques,” an Ortho publication, rap each stone firmly with the handle of the trowel to make sure it is seated properly. The paperback book does an excellent job of describing the construction of a flagstone patio, as well as many other masonry projects.
The flagstones need not fit together perfectly or even close to it, but keep them about half an inch from each other and from the edges of the patio. Before you begin the job, get a fairly long level and keep it handy. After you get down a few stones, place a 2-by-4 or something similar across them.
Put the level on top of the 2-by-4 to find out whether you are getting the stone set the way you wanted. By doing this as you go along, you can make any corrections while the mortar is still workable. Put more mortar under a stone that is too low or press down on one that is too high.
Filling the Joints
When all the stones have been placed in the mortar, wait at least 24 hours before filling the joints. The joint mixture should be a little more watery than the original compound, since it has to go into small spaces. You also can cut down a bit on the amount of sand. Make it about two parts of sand to one part of cement.
When mortar gets on the surface of flagstones, it is difficult to remove if allowed to set even a few minutes. Therefore, as you work, keep a sponge and water handy so that if any falls on the stones, it can be wiped off at once, which means that second, not when you get around to it. Use any pointed tool to pack the joints.
The finished job must be kept moist for about a week. The best way to do this is to place a wet cover on the patio and see that it is fairly moist at all times. Many people merely wet down the surface a couple of times a day for five or six days. This is all right in ordinary weather, but if the sun shines on the patio very much, the surface will dry up too quickly and nullify your curing efforts.
