Installing Subfloor The Right Way

I think that one of my favorite things to do on the job site is install subfloor. Its all about production and rhythm. As a crew we put on some music, set the autopilot and sweat. Of course this all depends on the right techniques. There is a proper way to install subfloor but it isn’t “rocket surgery” as our engineer likes to say. I had a conversation with a rep at a major manufacturer and he said he’s called out all the time on issues with subfloor. So let’s go back to basics. For a list of my favorite tools, head over to my page here to my affiliate page https://acmetools.pxf.io/AwesomeFramers

First Row. Step 1, snap a line for your first row. Even though we’ve straightened the wall and the rim or the mudsill below this row, take the time to snap a line. A perfectly straight row means the rest of the floor goes well.

Step 2, use the highest quality glue you can find. After using PL Premium for years and using pneumatic glue guns, battery powered, and of course hand squeeze, we made the switch to Advantech Subfloor Adhesive. Nothing is faster than this system, and it works in the rain and snow too.

This was faster than a hand squeeze gun ,but still slower than a foam gun.

Long barrel gun improves speed and safety.

Step 3, layout the joists and fasten the entire first row before installing the second row. Ensuring that those joists are spaced properly means you won’t have to trim any edges of the panels.

2nd Row. Step 1, stagger by 1/2 panel for the second row. Our engineering notes require this and its best practice.

Step 2, glue the entire row, not one sheet at a time. Advantech SFA has a 20 minute working time and that is plenty for us to set sheets and fasten them.

Step 3, lay all the sheets for that row without stopping to tack each sheet.

Step 4, tap the sheets together at the tongue and groove using a scrap and sledgehammer. Don’t beat the sheets together tightly, you must leave 1/8” gap at all sides of the panels to allow for swelling. The sledge makes it easy to “persuade” the sheets together, but don’t hit it hard. Be very particular about that 1/8” gap.

Just lightly tap the sheets together and leave 1/8” gap at all sides of the panel.

Step 5, fasten the sheets before starting the next row.

Tips. I like to screw down subfloor using a stand up cordless auto feed system. While not as fast as nailing off a floor, it is easier on the body and reduces squeaks. For a two person crew, one framer glues and sets sheets while the framer fastening can usually help pack material and fasten sheets. This rhythm means the sheets are fastened within that 20 minute working time.

Make sure that any parallel rim isn’t fastened until after lines are snapped and the subfloor trimmed. This makes it easy to straighten the rim.