Framing the floor deck.

This stage of construction takes us back to somewhere near the end of august 2011. I had completed framing the basement walls, and had put up the load bearing basement partition walls that support the floor framing. I used engineered I-joists, rim board and LVL beams, then 3/4" tongue and groove plywood as a subfloor. Never having built anything using engineered lumber before, I was impressed by how straight everything was and how well everything fit together - which I guess is the whole point. The entire floor structure was built on one plane, which is to say that the joists were fastened to the structural beams using hangers, creating a flat ceiling in the basement.

The completed floor deck. The poly in the center of the floor is covering the hole for future stairs and stovepipe. During assembly, I was careful to install the "smooth" side of the rim board to the exterior, so the airstop tape would stick (more on this in later posts). I waited on the application of the airstop tape to the rim board until the last possible moment so as to avoid unnecessary UV exposure.

Before I could build the floor structure, I had to put up the load bearing basement partition walls. The process was pretty straight forward with the walls being of 2x4s, 16" o.c. with a double top plate. After snapping a bunch of chalk lines, I used adhesive (QB300) to secure the walls to the concrete surfaces. Not using fasteners through the bottom plates eliminated the risk of accidentally puncturing one of the PEX tubes which are only about 2" below the surface of the slab. While the adhesive was curing the walls had to be braced. I used boxes of nails to keep the bottom plates on their chalk lines - they otherwise want to "float" out of position on the adhesive.

There were four load bearing partition walls to put up before framing the floor - one wall has a door opening in it and so required a header. If you look really closely at the plywood sheathing behind the two partition walls on that side, you will see two little pieces of airstop tape (3M 8067) that would later be connected to the second top plate as per my air-sealing strategy. If you look closely at the plywood sheathing below those two pieces of tape, you will notice that I forgot to do the same thing at the mid-wall seam. I was able get tape back there, but it would have been better if I had remembered before putting up those walls.

I purchased the joists, rim board and LVL from Kam Ridge Manufacturing, the same place that I ordered my trusses from. I provided the critical dimensions (some of the measurements had changed from the original set of plans) and Kam Ridge provided a layout for the floor structure. The materials were delivered slightly longer (~4") than what was required so that I could cut everything to an exact length. With the joists and beams all being on one plane, there was a fair bit of strategizing and measuring involved so as to ensure that the structural elements were all in place where and when they were needed to support the joist hangers.

We installed as many of the joists as we could before stopping to set up the various beams that had to carry the joist hangers. Above and slightly left of where I am standing in this photo is where the hole for our future staircase is to go. The opening in the floor was framed with a number of intersecting beams that either had bearing on one of the load bearing walls or on a hanger at another beam.

From this angle the hole is above and slightly to the right of where I am standing. The orange coloured lumber are LVL beams already in place. Notice that we hadn't gotten nearly as far with the joists behind me since there was as yet nowhere to hang one end.

Here Peter is "helping" me with the subfloor... We were apparently using a piece of rope to do something... To install the sheathing, I applied QB300 adhesive to the top of each joist before laying down each sheet of plywood - then nailed with 2 3/8" air nails. When nailing, it is a good idea to leave the last nails out until the next sheet of plywood has been set down and the tongue and groove of each are seated. In other words, if you end up nailing each sheet down completely, you will likely find it almost impossible to get the tongue and groove to seat later - even if you use a sledge hammer.

Here you can see how hangers were used to carry the ends of the joists. In some cases, hangers were used on both sides of a beam. I used a small dab of QB300 adhesive at the bottom of each hanger (in addition to the required fastening) so as to prevent the joists from "squeaking" in the hangers.

Here is the completed hole-in-the-floor. You can see how all the intersecting beams come together to shape the hole. I really like the overall look of the flat ceiling in the basement and the hole in the floor, but this design may have increased the amount of LVL required as compared to a more conventional design - and LVL isn't cheap.

Who - The Sheepdogs