Do you think contacting the manufacturer might be a good idea?

You should be able to find that information in the installation instructions. Building codes typically defer to a manufacturer's published minimum clearances to combustable materials from the edges of the firebox in all 4 directions. The clearance from the firebox to the floor is often the height of the unit. If not you would need to raise it or provide a non-combustible material on the floor. If you don't have the instructions, you can usually find them online.

I think the absence of a non-combustible material on the floor will not be attractive. Quarry tile with a bullnose edge is easy to install. No reason to raise the fireplace.

LVP has a maximum Temperature rating. Find out what your manufacturer states and what the output is from the fireplace. You will then know whether it requires a hearth or not.

Please post the brand and model of the gas fireplace you are installing so we can review the installation manual. That information will most likely be found there.

I think what Mark is saying is that when you install a fireplace without a hearth, it looks odd. I agree with that 100%.

I only find good advice in PPF's comment.

I have no particular knowledge of how LVP reacts to heat when run up to a gas fireplace. So I did a little research on this via Google and found this post that describes discoloration with hardwood flooring. I would think the same may occur with LVP:

http://www.city-data.com/forum/home-interior-design-decorating/1972371-gas-fireplace-safety.html

My best guess would be that raising the fireplace 6" as you suggested might minimize or eliminate potential discoloration from heat. Yet it is certainly not required from a safety standpoint according to your installation instructions. You could even run carpet up to that fireplace and it would still meet code. I agree with PPF that contacting the LVP manufacturer is the best way to get determine if raising the fireplace is necessary.

After being in the fireplace business for nearly 30 years, I personally have a hard time accepting the look of a traditional fireplace without a hearth. Meaning a fireplace with a mantel surround. But that is purely subjective. If you are aiming for a more contemporary look, similar to a linear gas fireplace, I think it would look best raised in the wall even more than 6".

What type of surround do you plan on using around the fireplace? What look are you trying to achieve and what style of decor are you planning for the room? Answers to these questions will help you decide whether or not raising the fireplace off the floor is appropriate regardless of whether it is necessary.

I have used linear fireplaces in my designs, the latest in remodeling a mid-century house into a Mid Century Modern house. The linear fireplace was used to create an emotion that amplified the desired MCM ambiance. The end design has a raised hearth because my client wanted display space for sculpture and pottery.

We recently installed a Mendota fireplace, and the installation instructions included the clearance requirements for just about every type of installation possible, including raising it off the floor. You need to pick some brands you may use and download their installation instructions.

Bruce

Our fireplace is a zero clearance. We have a hearth.