Oz -
The inside of my fire pit is 4' the company I ordered from suggests 2-3" of glass - but my PB told me NOT to get that much. He said propane is so heavy - you don't want to cover the ring with that much glass. So I ordered a little less than 2" worth.
I got:
120 lbs x Onyx Black Metallic / Black Reflective
40 lbs x Gunmetal Gray Metallic / Reflective
15 lbs x Black Diamonds - these are larger black hunks - Ill try to get a pic of it later.
In my contract, my PB was going to do lava rock - but I asked if he could build up for glass instead. Here is what they did. They took the same large cement looking pieces that they used to build my fire pit with - and they stood them up in the bottom (center). They looked like this - but were a little smaller (I guess).
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Untitled by
Wendy Baldwin, on Flickr[/IMG]
Then he took a large piece of sheet metal and cut it to fit larger than the inside (not sure exactly the size) and then cut slits about every 2" around the side and bent them up. He sat the metal piece on top of the standing cement blocks and then screwed in the bent up sides of the metal to the wall of the fire pit. (not all, just some of them) There were also a few holes he drilled in the metal for drainage. Then he put the fire ring on (just a little bit above the metal).
Then we took the fire glass and slowly poured it onto the metal and spread it out. Once we got it on there - where it just barely covered the ring - he fired it up. You could see where we had put the glass on heavier - the flames weren't coming through the ring as well. So he smoothed the glass around the ring - so that there wasn't as much right on top of the ring. He was very concerned about me trying to light it. I got lecture after lecture about Propane being so heavy and how to be so careful to light it or it can blow.
I have a lot of leftover glass, we didn't use it all. He did said the tried to put the metal as close to the bottom of the fire ring as possible so I didn't have to use as much - but I probably have 15 lbs of the glass and ALL of the nuggets left. So it would vary greatly depending on how high you put the metal to the fire ring.
He said that some of the glass will shift and fall through the metal - so I figured I would keep some on hand to top it off if needed. The nuggets were only going to go on the very top - but it didn't need them. I could probably return it - but I keep thinking I could figure something to use them for. I am sure S&H back is killer.