Rim board and I joists

[andrew whicker]

Hi,

General construction question:

When did the industry start using I joists and OSB Rim boards?

I'd like to continue to do some indoor railings for customers and wondering what I can expect.

[Mark Bolton]

They've been around since the 70s but in the areas we've been in they didn't really become commonplace until about 25-30 years ago. Early to mid 90s. I can't remember when they were implemented into the IRC but I'm sure some googling would show when they hit the code.

[andrew whicker]

Thanks, I'll google around some more.

How does the OSB rimboard take a lag screw (3/8")? Looking at anchoring an indoor railing.

[Mark Bolton]

It's very sound material as long as it didn't get overly wet during construction. We were always getting 1 1/8" material. I can't say I wouldn't be more comfortable with solid wood blocking behind but if you have no access to the interior to back it up it is what it is. I'm assuming your talking about the lower rail of a railing (down where the rim is). There isn't as much load the as at the handrail so I'd be less concerned.

[andrew whicker]

I have to build a guard rail around a basement stair going into the floor. I'm talking about anchoring the guardrail at the bottom.

[Lee Schierer]

Thanks, I'll google around some more.

How does the OSB rimboard take a lag screw (3/8")? Looking at anchoring an indoor railing.

Check your building codes, lag screws may not be allowed for what you are doing. In our area using the IRC we cannot attach a ledger board to a regular rim joist with anything but through bolts or structural screws.

[Ole Anderson]

Check your building codes, lag screws may not be allowed for what you are doing. In our area using the IRC we cannot attach a ledger board to a regular rim joist with anything but through bolts or structural screws.
Yep. Structural screws are so much easier to drive (no predrilling required).

[Malcolm Schweizer]

My parents built their home in 1996 and they used OSB I-beams and they are horrible. The floors are so bouncy that if you walk lightly past the grandfather clock, the chimes swing into each other. I will never ever use this construction method. I am also not a fan of OSB in the first place. I would use plywood instead. I am visiting the US and I noticed a lot of new construction where they were using OSB on the roof. I was surprised- I would have thought code would require plywood.

[Mark Bolton]

My parents built their home in 1996 and they used OSB I-beams and they are horrible. The floors are so bouncy that if you walk lightly past the grandfather clock, the chimes swing into each other. I will never ever use this construction method. I am also not a fan of OSB in the first place. I would use plywood instead. I am visiting the US and I noticed a lot of new construction where they were using OSB on the roof. I was surprised- I would have thought code would require plywood.

If that's the case they were likely either under-sized or designed on the Fly because of you install I joist to spec and with appropriate bracing youve got a floor that you could drive a Sherman tank running across and no china cabinet on anywhere in the building will ever vibrate. It's all in the design and execution and if you don't stick to the standards and you don't do a good job all the way along you're not going to wind up with a good end result. I joist allow us to span phenomenal distances that would not be possible with any sawn Lumber.

[Malcolm Schweizer]

If that's the case they were likely either under-sized or designed on the Fly because of you install I joist to spec and with appropriate bracing youve got a floor that you could drive a Sherman tank running across and no china cabinet on anywhere in the building will ever vibrate. It's all in the design and execution and if you don't stick to the standards and you don't do a good job all the way along you're not going to wind up with a good end result. I joist allow us to span phenomenal distances that would not be possible with any sawn Lumber.

Something must be wrong for sure- the span is not very long. One room has a span of maybe 15', and that room is just horrible. You almost are afraid to walk on the floor.

[Lee Schierer]

Something must be wrong for sure- the span is not very long. One room has a span of maybe 15', and that room is just horrible. You almost are afraid to walk on the floor.

You might want to read the design manual for OSB joists (https://lpcorp.com/media/1381/lp-solidstart-i-joists-residential-technical-guide-canada.pdf) which shows the proper spans and joist construction.

[Jim Becker]

Malcom, my shop building uses I-Joists for the ceiling and second story floor above....and it's rock solid. The building is 22' x 44' and the I-Joists are 12" deep, spaced generally 16" OC. I can jump hard on the upstairs floor and the only bounce is probably because there's only a single layer of 3/4" plywood for the flooring.

[Mark Bolton]

Often times joists pushed to their limit with no ceiling/sheathing/bracing below will result in a floor that "drums". The deck at likes the skin of a drum. If the joists are open below running a couple runs of 1x3 strapping nailed to the bottoms of the joists and they must be touching the sills at the edges will make the floor solid as a rock.

[Ole Anderson]

Parallel long beams (joists in this case), must be braced to one another or they can buckle at less than the load limit. hence "X" bracing below your floors..

[Mark Bolton]

Unless the design/span specifically requires it, bridging or cross bracing with I Joists is most often not necessary.

From TJI Tech Specs:

Bridging is often required in floors or roofs when solid-sawn lumber joists are used. ... Trus Joist® TJI® joists are made with no observable twist and have minimal material variation between joists within any specification group. Consequently, theydo not see any significant benefit from bridging.


We've had a couple of jobs where the spans were quite long and in a large wide open room and the drumming issue was apparent. Simply running strapping from sill to sill down the center line of the joists butting the ends tightly together and butting them tightly to the sills completely eliminates the problem.

[Jim Andrew]

I started using I joists back in the 90's because of the strength and evenness of the floor. And houses got bigger, and we needed longer spans for the homes people wanted to buy. With lumber floors, we always had gripes about squeaks in the floor, I got to using screws to fasten down the plywood, and it helped a little. But I joists got rid of the complaints, as they are so even on top, the floor is flat, so no low joists where the plywood pulls the nails up.