Because the fireplace is off the ground, I needed to build a hearth to support the fireplace surround I purchased. I built the hearth to the width and height I needed, minus an inch. I cut the carpet out underneath, so it could be flush with the floor and screwed it down and into the existing studs. I'd later wrap it in 1/2" cement board and use two layers on top for added fire safety.

Made of 2x4's I added a header above the unit and attached it with pocket hole screws to the existing framing on either side of the fireplace. My manual told me a header could exist above the standoffs (Those are the triangle shaped pieces on top of the fireplace.) This ensures adequate clearance between the wood (which is combustible) and the fireplace unit. I installed the header right up to the standoffs as it was the exact height I needed. The mantel had key holes in the back, so I installed 4" lag screws to catch those.

This surround not only fit the mantle clearance requirements for my fireplace, but it is also made of fiber glass which is non-combustible, so I felt extra safe about adding it. We lined it up on the lag screws and temporarily supported the legs with two 1/2" scraps of drywall on each side until we got the cement board in.

I used Rustoleum High Heat enamel spray paint in white to update the exterior of the metal on the unit. The black and brass didn't fit the look I was going for. I put painters tape inside the perimeter of the opening (facing me) then stuck cling wrap to it to protect the interior.

I then sealed the fireplace according to the manual with High Heat Mortar. I put this between the metal fireplace and the drywall sides as well as the wood frame bottom (these are both allowed to be adjacent on my fireplace as long as it is sealed).

I cut Durock 1/2" cement board with a score and snap (just like you'd do for drywall), then attached it to my hearth frame with hardi screws. On the top I used a second layer for an inch of non combustible material over the framing.