When installing a fireplace, one of the most important elements to get right is the hearth. The hearth is a large, fireproof area that prevents fire from spreading from the chimney area into the room. Hearths can be made of cement or tile and are fairly easy to install yourself.
Creating a cement hearth is not difficult, but you will need some medium-density overlay (MDO) plywood to make the cement block for the mantle. The project requires four pieces of MDO cut to the size of your hearth area. You also need a piece of plywood on the bottom of these four pieces to make an enclosure. Add some supports to the bottom of your frame to keep the frame from bursting when the cement is poured. Also caulk the inside to prevent cement from leaking out. Allow the caulk to dry, and then pour your cement. Smooth out the concrete and pound the sides with a rubber mallet to remove air bubbles. Allow it three days to dry then remove the frame. Because the concrete will be extremely heavy, have some help when moving it into place.
Before placing the concrete, mark out the area so that you get it placed centre to the chimney. Lay down a small amount of cement along the length of where the hearth will be placed. This is called a bedding. The bedding needs to be 5 to 10mm thick. Place the concrete slab on top of the bedding, and push down on it until it is level. Use a level to ensure it is straight.
For tile to be placed, the area in front of the chimney needs to be smooth and free of bumps. Use a small mixture of mortar to smooth out any patches. Mark out on the substrate, or lowest level of the flooring, how big the hearth will be with a centre line and subdivisions for each tile. Dry-lay each tile into the hearth area until you have the correct pattern. Lay these tiles in that order on a spare board so that you can use that arrangement for their final placement. If any tiles need to be cut, do so using a tile saw. A tile saw can be rented from most hardware stores. Mix a portion of dry thinset and latex adhesive in a bucket and spread a layer onto the substrate using a trowel. The adhesive needs to be smooth. Using the grooved end, scrape along the adhesive to mark grooves into the adhesive. Then you may begin putting your tiles into place, doing small portions of the adhesive at a time. Use spacers between the tile to make even spaces for the finishing grout. The thinset will dry in about 30 minutes. Once the thinset dries, apply grout into the spaces between the tiles to hold them into place. Scrape off excess grout from the top of the tiles once it has begun to dry.