Replacing Hardwood: Part 5 – Shimming

After yet another trip to Home Depot with an AutoShare cargo van, we think we have everything we need to start (and hopefully finish) the subfloor. 

Our house isn’t level, but we decided to make the concrete hearth level. If it weren’t for the hearth, we would just install the subfloor over the original subfloor and live with some un-levelness. But there is a serious difference in thickness across the hearth and it would be extremely noticeable if we didn’t level it.

To level the subfloor, we’re using regular plywood. We lucked out because the difference in height between the lowest and highest points is exactly half an inch and you can buy 1/2″ plywood sheets!

The first plywood sheet – or shim, really – had to be cut to fit around the hearth. We also made sure we left a 3/8″ gap around the perimeter to allow for expansion. My dad and I have a difference in opinion about whether the plywood will expand. I’m not taking any chances. We used pieces of our old subfloor (which was 3/8″ thick) as our spacers since we had lots of little pieces of the old hardwood laying around. But you can also buy these at a hardware store.

We also cut an opening for the vent.

Then we just screwed it in place. Easy-peasy once the cuts were made.

As we continued to work our way from the window, we had a few puzzles to figure out. The first was to figure out when to taper off the shim. We used a combination of 1/2″, 1/4″ and 1/8″-thick sheets to get the floor as level as we could. There was still a small dip in the middle of the hearth, so we also filled in the dip with more shims.

We’re being particularly meticulous because that hearth needs to have the same thickness all the way around or I’ll notice it forever.

As we moved away from the fireplace toward the front door, we had another small challenge. Although the floor required the same shimming as the living room, we knew we couldn’t shim it up as much because the front vestibule wouldn’t allow the height. So not only were we changing our shim heights away from the window, but we were changing the height as we moved away from the fireplace.

We ended up with something like this:

Technically the plywood should have gone all the way to the front door, but there just wasn’t enough height clearance, so it now goes downhill slightly.

The shimming is now complete and we’re ready to put down our subfloor. Or so we thought…