How do I get the first rows started when I cannot nail or screw the backer block down since I risk hitting a hydronic heating water pipes?

All the herringbone guidelines I've read say to nail or screw down the backerboard for the first course.

My best idea thus far:
1. Tack down an oversized backer-board with just a dab of glue in the 4 corners and set the Bostik glue can on it for weight. Board would perhaps be 3'x3' - this way it is easy to see that the corners are still on the line and that the board hasn't shifted.

2. Immediately install the first two boards, one for each row, with tongue against the backerboard.

3. Let dry for 24 hrs then come back to finish the install.

Also, I've not installed much herringbone to begin with, so after the first row is done do I need to use the backerboard again?

Thanks!

I can't think of any easy way to do this. All you can do is glue a couple of pieces in to start .This is going to take a long time to install.

Why don't you try using a fast grab adhesive for the first few rows of blocks/all the job? It would cut down on your 24 hour wait time!

Gluing the backer board is a good solution. I wedge mine from a wall to give a solid base or just use a number of laser lines to ensure the blocks stay straight and omit the backer board (experience helps with this way).

Please tell me they are engineered blocks!