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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 2×8 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 2×8’s drilled through the middle. No notches in the bottom anywhere on the joist.

Certainly a 4″+ notch out of a 2×8 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 2×4’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.

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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».

How to Fish Electrical Cables

Lacking X-ray vision, you can’t know exactly what’s behind your home’s walls or above its ceilings. That’s why fishing an electrical cable to a new outlet or switch, like any fishing expedition, takes time, patience and a certain amount of trial and error.

But, given the standard spacing of studs and joists typically, 16 or 24 inches on center there’s a good chance you can predict where the obstructions will be. You can also use a stud finder to locate framing you can’t see. Thus, with patience and a little luck, you can extend cable from an existing power source to virtually any new location, without chopping a bunch of unnecessary holes in your walls, floors or ceilings. Or, you can move the new outlet slightly so that running cable to it is easier.Three more caveats: First, always turn off the power before handling electrical cable or devices. Second, get help. Typically, one person feeds metal fish tape down into a wall cavity as a second person, with another fish tape, tries to catch the first. It’s a pretty futile exercise trying to do it by yourself. Third, whenever you drill or notch into framing members to run cable, protect that cable with steel nail plates attached to the edge of joists or studs. Otherwise, when you cover up the framing again, you could drive a nail or screw into your new wiring.

How to Run Cables From Above If you have an unfinished attic, you can probably route cable down into a wall outlet immediately below. Locate the wall’s top plate and, with your spade bit, bore a 3/4-inch hole through it. Thread fish tape through that hole into the space between two studs. If the tape hits something partway down the wall, you’ve probably encountered a fire stop, a wood block nailed at a right angle to a stud or joist to seal off the air passage and help prevent fire from spreading. To get cable through a stop, you’ll need to open up the wall above it and notch the block. Use a hammer and chisel, and wear safety glasses.

If there are no stops, your helper downstairs (who’s already cut an outlet hole in the wall with a drywall saw) can yell when he or she sees the fish tape coming down from above. To grab hold of that fish tape the metal is stiff that person will need a second fish tape or, in a pinch, an unbent coat hanger.Connect the cable to the fish tape with electrical tape as shown in the animation, then reel in the tape and cable. To wire the outlet below, you’ll need at least 7 to 12 inches of cable to protrude from the outlet opening.

How to Run Cables From Below If your basement has an unfinished ceiling, you can run cable from there to a first-floor wall outlet. Just below the opening for the new outlet you want to wire, right where the wall meets the floor, drill through the floor at an angle with a 1/4-inch bit. Shove a coat hanger into the hole, then go to the basement. The coat hanger is aligned with the wall’s surface, so if you mark a point 2 1/2 inches from the coat hanger, that mark should put you right in the middle of the wall cavity. Using a spade bit, drill a 3/4-inch hole straight up through the subfloor and bottom plate.

You can probably push a new length of cable up through the 3/4-inch hole to the outlet opening in the wall. If pushing doesn’t work, try fishing it from above. Again, to wire the outlet, allow at least 7 to 12 inches of cable to protrude from the opening.

How to Run Cables Across Joists and Studs If you can’t fish from above or below, however, sometimes you just have to cut into finished surfaces and either notch into or drill through framing members. It’s a messy business.

In plaster (top), open up the ceiling along the entire cable run, and remove parallel strips of lath. Bore 3/4-inch holes through the joists. After running the cable, patch the opening with strips of drywall. To match the thickness of the plaster, you may need to build up a couple layers of drywall. This is a good time to repaint the ceiling.With drywall (bottom), make an opening at each framing member and cut a 3/4-inch notch into its edge. After cutting the notches, run the cable and shield it at each notch with nail plates. Patch the holes.

By the Book

According to most building codes, you may not cut or drill into any joists smaller than 2-by-6s. For joists that are 2-by-6 or greater, you can notch no deeper than one-sixth its total depth (e.g. 1 inch deep for a 2-by-6). Finally, never notch a joist in the middle one-third of its span.

Tips From the Pros If you have lots of corner notches to cut, consider renting a reciprocating saw. Its replaceable blades can get into spaces where nothing else will saw. If there’s any evidence of nails in the wood you’re cutting, use a metal-cutting blade and always, but always, wear safety glasses.

Cut into the juncture of the wall and ceiling as shown. Notch the wall’s top plate to accommodate the cable. After you run the cable, protect it with nail plates wherever it passes through notched framing. Run the cable down the wall.At the base of the wall, you’ll need to cut back finish surfaces across the edges of several studs. Happily, this channel can be covered by a baseboard. But again, before replacing finish surfaces, add nail plates to protect the cable.


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