Joist trak with TJI floor joists

ordellrobbie

Running into an issue with joist trak and TJI framing. The flange on the joists are 3 1/2” wide. The bays are 16” wide. The plates need to be 8” apart. Because of the 3 1/2” flange, every 4th or 5th bay I can’t get the 8” spacing because the flange is so wide. At that point the spacing ends up being 11” because the flange is in the way of where the 8” spacing would be. I’ve tried all different ways to try to make it work and it doesn’t seem possible. Has anyone ever run into this problem? If so what did you do? I’m thinking every 5 feet or so they will feel a cold spot if I keep going the way I am but I can’t come up with another solution. 

ScottSecor

Just a thought if I understand your problem correctly. Could you 'rip' some of the aluminum plates down slightly to make them fit between the bays? I have seen aluminum cut on a table saw (with carbide blade) on many occasions. Obviously gloves, goggles, etc. should be used.

ordellrobbie

I could but now I would only have have of the plate. Not sure if that’s worse than just having the spacing off. I would have to rip down the whole side of the plate

KC_Jones

So joists spaced at 19.2" per manufacturers spec gives a bay of 15.7", if you have a full 16" space then it wasn't framed to spec, but that's another discussion.

So working from that spacing you would have to lay out at 9.6" spacing to be consistent across the entire floor.

So the question is, will that spacing, with those plates, give you the heat output you desire and not have hot spots. I think one would also need to know what floor covering is going over this.

The output question is for others more knowledgeable than I, I just wanted to clarify the dilemma you are having.

Picture attached for clarity, is this your issue?

hot_rod

That must be a beefy TJI, the flanges are usually 2- 2-1/2" wide?

Regardless, either rip them down, or overlap. Overlapping will put an air gap between some of the plate and floor, however.

Any idea what the load is? if it is on the low side, below 15 BTU/ ft, maybe one plate and one bare tube per space, or throw some UltraFin on the bare tube.

JUGHNE

The original "TJI" brand used the narrow top and bottom cords made of 16 plies of wood. Mine measure 1 3/4 x 1 1/2.... 3/8" plywood for the web.

New "value engineered" ones use what looks like a 2 x 4 top and bottom cords and web of chip board. The 2 x 4's are finger jointed.

Then the 19.2 OC spacing really put the economy hat on.
That was tried a few times here but most went back to 16 OC.

I haven't seen true TJI's here for over 20 years

STEVEusaPA

Are they thick aluminum plates or the thinner ones. If the thinner ones, maybe you can rent a brake like they use for siding and put an offset bend in them so one can slightly overlap the other and remain flat to the bottom of the subfloor.

Zman

I am confused. The joist tracks are 3.5" wide. You need 2 per bay to average 8" OC spacing. The bay is 12.5" wide the joist tracks take up 7" of that space leaving a 5.5" space in between. What is the issue? Are you trying to leave exactly 8" between the plates? I have never heard of a design like that.

KC_Jones

We need the OP to reply to the picture I posted.

The OP stated the bays are 16” wide, not that the framing is on 16” centers.  Those particular joist have a design for 19.2” in centers which gives roughly the 16” wide bay the OP describes.  The problem isn’t overlapping the plates, he’s running into structure trying to get to 8” spacing.  The picture I showed is the layout that is possible to keep 2 runs in each bay, he ends up with 9.6” spacing.  If the OP tries to keep 8” in one bay the next one will be over 11” and then 8”, then something even greater than 11”.  It will be a mess of spacing.

I’m no expert on laying out the tubes, just trying to add clarity to the problem they are presenting.

ordellrobbie

Yes KC. You are correct. The space is 16”. The joists are not 16” on center. 

Zman

Sounds like you probably have 19.2" OC layout. Your insulation contractor will not like this either.

Why not run your tubing at 9.6" OC layout (2 per bay) and be done with it. Are you that close on the heat output? You may have to increase the water temp a few degrees to make up for the increased spacing.

ordellrobbie

Zman. Not sure why. The rep said it has to be 8”. Heating the house is not a concern. It’s cold or hot spots I’m concerned about

ChrisJ

ordellrobbie said:

Zman. Not sure why. The rep said it has to be 8”. Heating the house is not a concern. It’s cold or hot spots I’m concerned about

I don't think there's much more you can do other than spread it all out as evenly as possible.

Zman

What type of flooring is going on top? I would be surprised if your feet could tell the difference.
If you want to get super meticulous, you could run 3 per bay in areas with high traffic.
I would not go where you are headed, did you tell the rep that you have 19.2" OC joists and that you are planning to rip the plates?

ordellrobbie

Zman  Hardwood floors. I do not plan on ripping the plates. I suggested it and he said not to. What I’ve been doing is going 8” spacing util I can’t. Then I go 11” in that bay and go back to 8 again. So every 4 or 5 bays the spacing is wider. I only installed about 25 plates and then stopped because I want to get this figured out first. It’s not a lot to take down a redo. I’m just trying to figure out which would be better. The odd spacing like I started doing or wider than manufacturers spec at 9.6”. 

Zman

Ok,
I think you are trying to follow a rule that really doesn't exist. They say 8" because most joists are laid out at 16"OC. Tubing can be run at pretty much any spacing you want, you just need to make sure the heat output is within range. You will never feel a difference between 8" and 9.6" through a hardwood floor.

hot_rod

The most important part is that you get all the tube installed that is required. Sometimes you end up with three loops in one space two in the next.