Is A Box Flush Fireplace Hearth Better Than Lipped & Curved Hearth?
A Fireplace hearth is the base section of your fire surround and arguably an important decision to make when purchasing a new fireplace. Some fire surrounds can nowadays be supplied with a choice of hearth edge profiles (see example of some of the finishes we offer at Creative Fireplaces below) & heights. The most common hearth type which is pretty much standard in the UK fireplace industry is known as the “boxed and lipped effect”. 
This hearth has a 20mm horizontal section with a 40mm vertical section recessed about ½” (12mm) back. The overall hearth is hence 60mm thick (2 ½ inches) and has a ‘boxed and lipped effect’ just like the name suggests 
Advice on picking the right hearth
1. If you’re worried about children hitting their head on the sharp edge of a raised hearth, then it is possible to curve these edges. At Creative Fireplaces we even offer a specialist range of boxed flush hearths with rounded corners which is ideal for this requirement 2. Another space saving solution is a bowed (curved) fireplace hearth. The hearth has the same 15” (380mm) depth in the middle & hence will comply with the Gas Safe Register regulations of a 300mm overhang from the front of the hearth to the edge of the fire, however will visually look smaller due to its curved design
3. It is also possible to have a flat hearth, which does not have a raided under section. These hearths are typically 20mm or 30mm thick and not very common as the majority of the hearth will be hidden if you lay carpet (due to the pile of the carpet) or wooden flooring up to the hearth. For this reason a standard 2 ½ inch (60mm) fireplace hearth is the most common height