So you've finally got everything finished and ready for installation and you've bought our recommended glue. So is there a recommended fastener type and pattern to be used for mechanical fasteners (nails, screws, nothing...)?

You'll want to apply the glue in an "S" pattern and make sure you have good coverage - you really don't need to overdo it on the glue, but want good coverage.  The PL Premium is good stuff and there's no need for the tread to "float" in a bed of glue.

Installing a retro tread

The glue will do most of the holding work for your new retro treads once it dries, but you'll want to use a finish nailer to shoot a 2" long finish nail into the corners of each tread to hold it in place while the glue is drying. If you shoot it in the back corners and close to the walls, the hole left from the finish nail is very small (almost invisible if it's in a shadow) and a dab of putty or a fill stick will cover it up nicely.  Usually, about 4 nails per tread is plenty as long as the new retro tread sits cleanly on the old tread.  Remember, the purpose of the nail isn't so much as to hold the tread permanently, as much as it is to hold it long enough for the glue to dry.  Thanks again for your order and remember to send us some photos of your finished project - we love to see them!