Stair builder question.

[Ron Bontz]

It has been a long while since I put a set of stairs in. The relative who wanted to use Tigerwood flooring for her floor, ( now wants Brazilian Oak, BTW), is putting the flooring all around her stairs. 3 sides. For the life of me I can't remember if the bottom bull nose goes down before, (under), or around the corner post. The last time I did this I used a rail bolt wrench to connect the post to the floor joist. Also, this house has TGI floor joist. Doesn't seem like that would hold very well. None of my text show or talk about this particular question. Dementia setting in, I guess.:o Thanks in advance.

[Tad Capar]

Ron,
If I got this wright, you'll putting a flooring around the stair opening (2 sides and front), I presume it's a new construction and there is no railing in place.
I assume you'll be installing 2 posts, one on each side if stairs.
If so, I would install these posts first then undercut them about 1/8" to slide your bull nose under it for cleaner look, regardless which way you end up installing your post.
I would remove a small section of sub floor (area where you need to attach your post) to see if you can beef the tgi up by gluing and screwing with 2x or 3/4" plys, bolt the half notched post to it.
If when laying it out, the post would winds up to far away from the stairs, then you can always install it from the top only (the way you described), you can screw it to the top of tgi ( the flanges are made of 2x anyway).

[Mark Bolton]

The chords (flanges) of TJI I joists (silent floor) are actually small paralams/LVLs. They are laminated rather than sawn material. The top and bottom measure 1 3/4" wide x 1 1/4 - 1 3/8" tall depending on the joist. The webs are 3/8" thick. This means you will need approximately 11/16" material to pad them out flush.

As mentioned building the web out to make it flush with the outer edge of the chord/flange is perfectly acceptable. You can even drill/bolt anywhere through the web but not the chords.

That said, I would imagine, unless you happened to land perfectly over a joist you will wind up cross blocking between two I joists with sawn material to give you something to bolt to. This is of course simple, notching your sawn material for the I joists, construction adhesive, screws through the web.

As for the post penetration, I have seen it done all ways. Post dado'd to accept the flooring as mentioned, post penetrating the floor with small trim around it. Post penetrating floor, cut tight, and left that way.

I think it moreso depends the other details on the staircase. Keeping it consistent.

Mark

[Ron Bontz]

Thanks Tad. Yes it is new construction. The person who framed this is not exactly a master craftsman in my book. Lots of cheap corner cutting it seems. The scheduling is messed up as well. The railing goes around two sides. A possible drop to go down the stair wall, around a landing and to the basement. I was thinking along the lines of cutting a whole in the floor and lag bolting the two post/newls to the joist. The third 1/2 newl is fastened to the wall. Then running the bull nose, same thickness as floor and slotted, in between for the flooring to connect to. The same as you would the top landing step transition. Otherwise I thought of using 5/4 and routing a recess and round over along one side for the flooring to slide under and maintain a clean appearance. I could then either add a dado-ed and edged board for wooden balusters or just drill the holes for wrought iron depending on the direction they go. Does this make sense?

[Ron Bontz]

Thanks Mark.

[Tad Capar]

Ron,
After reading Marks response and concern of bolting into a chord (flange) of the TGI we should have another look at it. Are these TGIs running along each side of the stair opening, or perpendicular to it with the rim boards/beams along the sides of the stairs? Another words, what kind of material is right there where you're thinking to bolt these posts to? If the TGIs run parallel, is there a wall directly under (I assumed there is/are, that's why I suggested you can screw to it from the top). Also, is TGI's chord made of a cut wood ( 2x2, 2x3 ) or is it a laminated chord, also, how wide is it? Is there enough room for you to screw your lag bolt to, keep in mind that you have to stay away from the middle if it (it already has a groove there and could be easily split)?
If your TGI is only 1 1/2" wide, there is really no room to screw to it from the top. My previous suggestion of bolting it to the side of it is much better way to tackle this problem and will be much stronger too.

[Ron Bontz]

Well I was up at the house putting in the tile flooring and took a quick look at the stair mess. TGI all the way around the steps. 3/4" OSB plates nailed to the TGI on the stair side. Stringers nailed to the wall studs along the sides, and to the back plate extending below the TGI, from what I can see. No straps or even a 2x4 kicker on the stringers which only set on the landing about half way. 2 x 12s glued and nailed down for treads. Last but not least, drywall cut around each step. Ya just gotta love it.
So, aside from a complete tear out, will the OSB have enough strength to hold screws from the landing skirt boards, as well as knewls?? Or is the whole wall going to have to be ripped out to the bottom of the TGIs, TGIs re-enforced with plywood between the cords and a plywood plate replacing the OSB?
Right at the moment, I sure don't like TGIs. Thanks for any in put. I have to go up in a few days and start on this mess. Getting ready for hardwood flooring.

[Aaron Wingert]

Not 100% sure of what you're asking in the last post Ron, but you cannot remove the OSB web or the flanges of the TJI's. It is common to add plywood or OSB to the web of an I-joist to faciliate attachment of stairs or other framing members.

You cannot run lag screws into the flanges of an I-joist...Nails are limited to 10d in the flanges in most cases.

If you could post a picture or two of what you're facing I bet we can figure out a solution.