Floor Joists

July 14 2005

The nice HVAC Contractors who installed my furnace and re-routed my ductwork, unfortunately cut a more than 4" notch out of two of my 2x8 floor joists.
The notch is only about 3" on the front sides, but it's more than 4" deep at the back of both of them.
I had thought that a 1" deep notch in a joist was ok there, based on this link: IB-206-Notches and Holes.pdf
With Ontario Building Code, the rule is notches only on the top near the ends, and holes smaller than 1.75" in 2x8's drilled through the middle. No notches in the bottom anywhere on the joist.
Certainly a 4"+ notch out of a 2x8 nobody allows.

I had glued and screwed some incredibly hard wood on the bottom. It took half an hour to cut each of those curved notches out of them with a sabre saw that wood is so hard. Fortunately, even though a year has passed, the joists have not sagged at all. They are still flat and true. Nevertheless, they are not structurally strong enough.
Both the black and the copper are natural gas lines. The black feeds the house with natural gas, and the copper runs to the gas fireplace upstairs over the notch.

Here's the parts list that Rod recommended.
- Bolts with washers
- PL 400 glue
- lots of #8 screws
- 4' x 7" of marine grade plywood. There's a thin vaneer on it, but the grain of 3 out of 5 of the layers runs the 4' long way.
- The joist hangers are for the end.

I am a little bit nervous about how much force it's going to take me to get the old wood off that I've glued and screwed. After the natural gas lines are removed, the plan is to cut them vertically at the notch, and then unscrew them and pry them off. But just in case I twist the joists with too much force, I've screwed two 2x4's under the joists to take some of the load during the work.

Here's two of the four pieces with the screws and bolts in place.

The installation plan is:
a) Have the HVAC guy remove the gas lines
b) Remove the bolts to panel A
c) apply PL400 glue to panel A
d) place and screw panel A (three rows of screws). Screws go at the bottom, bolts at the top.
e) apply PL400 glue to panel B
f) place and screw panel B (one row of screws)
g) drill the bolt holes at the existing holes in panel A, through the joist, through panel B
h) bolt the panels A and B with the nuts on the panel B side
i) drill the two holes, 1.75" and 1.5" for the natural gas lines, in the positions predrilled in panel A
j) Then repeat steps b through i for panels C and D.
k) Have the HVAC guy reinstall the gas lines, and do a pressure test.

BTW, this is an interesting drill attachment. Good for drilling holes and then quickly driving screws. It's a bit long and it wobbles, but it saves a little time changing bits.

OK the natural gas has been shut off, the copper line has been disconnected, and the black line removed.

After cutting the two pieces of hardwood, and trying a couple different things, it looks like driving a chissel up underneeth works fairly well. It still took about an hour to get these two pieces (well four pieces after I cut them at the notch) off the joists.

But that left a rough and uneven surface, so I sanded it smooth. Hand sanded because I didn't want to loose any more of the joist than I had to.

Below, from the back, you can see that although the notch is mostly about 3" deep, the cuts assend to more than 4" because of the way they were cut.

Glue pattern with the PL400 glue. I started with a wave up and down, but decided to fill in the rest. I ended up using 1.5 large tubes of PL400 sub floor construction adhesive (each tube 825ml).
So I used 1237ml of PL400 to cover 2.3ft^2 of wood, or 530ml / ft^2. Probably a lot, but Rod said to feel free to use a lot of glue.
The glue oozed out of the bottom, and out of every bolt hole and other hole I'd drilled in the wood
The glue smells. I don't have to leave the house, although it's that kind of smell that I wonder if I'll get high or brain damaged. I've turned on the bathroom fans, the clothes dryer on 'air only', and the house air-to-air-exchanger.

The plastic bag, put on earlier but shown more clearly here, is to keep sawdust out of the natural gas line. You can see that I tried to apply PL400 to the joists as well. It dripped. Eventually I put PL400 on the ends and top of the marine plywood to bond it to the chipboard too.

Unexpectidly, the glue held the board in place immediately without screws. After a minute it had slid down only about an 1/8"

All screwed in.

It took longer than I thought, so now a couple of hours have gone by, and all 4 pieces are up, and screwed and bolted and glued.
The HVAC guy has re-installed the main black natural gas line. We had to chip away a 1/2" bit of the concrete wall to get that 2' long pipe through the joists
The copper line (to the fireplace) will be attached at a later date, and is not only disconnected, but the line that would go to it is capped as well as shut-off-valved.

One other thing the HVAC Contractors did was to put the furnace shutoff on the ceiling between the return air and forced air ducts right above the maintenance panel of the furnace, which is on the side away from the stairs. Most people can't reach it at all, and the only reason anyone can find it is because I show them where it is.
Here's a picture taken with me laying on the floor looking up at the ceiling by the furnace.

Here's the corresponding section from "Electrical Code Simplified, based on the 23rd Edition of the Ontario Electrical Safety Code, pg 105"
which as I read it, says that the shutoff should be between the furnace and the exit (i.e. the stairs)

As far as I know there was no permit, and thus no inspections. Yet I discovered recently that the Town of Oakville seems to require a permit for the replacement of a new furnace. Town Of Oakville When are Building Permits Required? says "the replacement of furnaces and ductwork".