We spent several days working on the underlayment. To get the squeaks out, we placed screws every 6" all over the floor and along the floor joists. We used buckets filled with lead (from Joe's reloading supplies) to weight down the floor in the area we were screwing down. Two five gallon buckets stacked on top of each other - they weighed about 200 lb. I have bruises all over my arms from shoving those heavy buckets around.
Then there was the issue of the base of the fireplace. It is very irregular, being made of volcanic rock. After much deliberation, we decided to try grinding out the lower 3/4" to create a little indentation that the wood flooring could slide into. This was a messy job, as you can see. Volcanic dust everywhere, but the Angle Grinder was the perfect tool and Joe did a great job.
We used a floating installation for this hardwood. Since the underlayment is particle board (a commonly used flooring material from the late 70's) - we could not use a nail down installation. The particle board will not hold a nail. We did not want to have to pull it all up and replace it with plywood - so we were thrilled when we came across this wood flooring online. It is called "Heritage Reclamation Plank". It is solid hardwood 3/4" thick, but each 8" x 72" panel is constructed of a lot of smaller pieces laminated together, then hand scraped. This creates a very rustic appearance, perfect for the style of our home. We really like the look of the Acacia wood. It is a scrub wood - very hard - twice as hard as oak, and the natural color of the wood is dark. I notice when I cut it with the jigsaw - it smells a bit like mesquite.
Floating the floor meant gluing each of the panels together along the tongue and groove. The special tongue and groove glue arrived frozen - which is not supposed to happen to this product. The box says "Protect from freezing". We ordered another batch of glue. The shipping company lost it! Ridiculous delays.