A grill's heat shield helps protect the burner from meat drippings that cause corrosion and flame ups. Heat shields also aid in evenly dispersing heat across the cooking surface. Heat shields are sometimes referred to as burner shields, heat plates or radiation shields depending on the brand of grill.
Measure the length and width of the inside of the grill body half way between the burner and the bottom of the grill grate.
Put on the safety goggles and cut the expanded stainless steel to the measurements with the jig saw.
If your grill has rests for the heat shield, place the piece of expanded stainless steel on the rests. If your grill does not have rests for the heat shield, drill 4 holes where you measured for the expanded steel, screw the bolts into the holes, secure the bolts with the nuts and rest the piece of expanded steel on the bolts.
In a single layer, place the ceramic briquettes or lava rocks on top of the piece of expanded stainless steel and turn your burner on to test out the new heat shield.
To extend the life of your heat shield, it's helpful to burn-off any food drippings after each grilling by turning the grill on high for about 10 minutes without food.
Always wear safely goggles when cutting metal to avoid shards from getting in eyes. Only do this project with your grill when it is completely cooled.