Reinforcing floor joist

[sleddogg]

I had a plumber replace the first floor drains in our basement so they no longer hang below the joists, making for an easier and cleaner drywall ceiling installation. In one spot he had to re-drill through the joist for a 4" pvc. The new hole is only about 22" from the original hole in the same joist. There was no other option, and now I want to reinforce where the original hole is. These are glue lam I beam joists and I was wondering if just taking a pair of 2x6 running a foot or so in either direction and sandwiching the middle of the joist with 5/8 x 3-1/2" lag screws going in from both sides would be sufficient. Maybe toss in some glue just to be sure. There is a bathtub above this area so being more cautious is natural. Also, what is the predrill for 5/8 lag screws for framing timbers?
Thanks,
Lance Tonkinson

[JimD]

Lance,

You need to reinforce where your new hole is too. Whenever wood is removed, the joist is weakened. I would not worry about the size of the fasteners, however, I would use enough construction adhesive to attach the new pieces and some screws to hold them in place until the glue sets. Holes for big fasteners will also weaken the piece. You do not seem to have an option other than putting the widest piece of 2x you can install above and below the holes. It would have been better to sister the joists with another joist or even two before the holes were drilled and the pipe installed. At this point, you might want to try splitting a joist in two after drilling a hole for the current pipe location and then installing it around the pipe extending past the old hole by 3 feet or so. If you also glue the cut in the new joist, it should be pretty close to having installing the joist before the pipe.

Jim

[Dutchman46]

Another thing that You could do is with all the weight that can be on that floor, I would take a 2x4, and tap it in between the floor. Lay a longer 2 by, and use that for equaling the pressure across the hole area. Just a little pressure against the joist will help the are stay even when the glue dries. It will allow every thing stay more solid during, and after gluing.

[Rich P]

If you can find a manufacturer's mark on the I-beam, you can then make contact with them to find out what their drilling and notching allowances are.

[pelligrini]

More than likely you probably don't need to reinforce it. They are usually designed with certain tolerances for penetrations. The webbing of the truss isn't quite as important as the bottom and top cords.

What's the depth of the floor truss? Is this just a regular floor truss? and not a girder truss or anything?

We use mostly open web wood trusses around here.

[phi1l]

and then if you are still worried about it, you candouble up on the cross bracing between the joists in the area of the cut...

[cgallery]

How much material is left above and below the 4" hole? IOW, what is the dimension of the joist?

And you said it is glue-lam I-beam? So this has the chipboard webbing, right?

[Mr__Bill]

If you do decide to reinforce the beam I would use the same material the uprights are made of. You do not want the patch to expand and contract with the moisture and temp at a different rate than the beam. It will degrade the glue joint. You may need to layer the patch or place a piece on each side.

Propping up while allowing the glue to dry is a good idea too. I would however put a bit of upward bow, but not too much, to the beam to allow for some sag when the prop is removed.

Before I did anything I would, as stated by pelligrini, find out if it's really necessary.

Bill
Over here on the Sunny Oregon Coast

[sleddogg]

Not knowing specifically what code is in central WI, but I have not one cross brace in my floor. Joists are 12 inch I-Beam with the webbing consisting of what looks like OSB, and the top and bottom spans are 2-1/2" by 2-3/4" of what looks like a glued laminate, not unlike plywood but with different strands.
They range in lenght depending on which part of the home between 16-28' with the longer beams being supported by two full laminate beams, 12" high, sistered together, supported by two posts.

I know I have read in our local codes where it's OK to drill holes through these beams, but it has language about what percentage of the height the hole diameter can be and how close to the center of the lenght they can be. The whole purpose of using these in construction is that they can be drilled through, allowing to conceal what used to have to hang low and in the way.

I will use construction adhesive but was mostly curious about whether the lag screws would be overkill rather than just using a 3" dry wall screw or that they might actually further weaken because of having to pre drill. And what is the correct pre drill for 5/8 lag screw?

[jking]

I'm still not sure if reinforcing is necessary. How long is the span on the joist you want to reinforce? Was the hole cut in the center of the OSB web? How far from the end of the joist is the hole? Pictures? Why are you considering lag screws in the OSB web?

As stated before, these types of joists are designed to allow for some cutting of holes in the web.

[pelligrini]

I know I have read in our local codes where it's OK to drill holes through these beams, but it has language about what percentage of the height the hole diameter can be and how close to the center of the lenght they can be. The whole purpose of using these in construction is that they can be drilled through, allowing to conceal what used to have to hang low and in the way.

And what is the correct pre drill for 5/8 lag screw?

I'll usually use a bit with just slightly less than the diameter of the inside screw threads.

A very common code in the US is the IRC (International Residential Code). Most of the language about drilling and notching you speak of is probably in regards to lumber. Engineered products like your floor trusses usually go by what the manufacturer recommends.

This is from the 2003 IRC:

R502.8 Drilling and notching. Structural floor members shall
not be cut, bored or notched in excess of the limitations speci-
fied in this section. See Figure R502.8.

R502.8.1 Sawn lumber. Notches in solid lumber joists, raf-
ters and beams shall not exceed one-sixth of the depth of the
member, shall not be longer than one-third of the depth of the
member and shall not be located in the middle one-third of
the span. Notches at the ends of the member shall not exceed
one-fourth the depth of the member. The tension side of
members 4 inches (102 mm) or greater in nominal thickness
shall not be notched except at the ends of the members. The
diameter of holes bored or cut into members shall not exceed
one-third the depth of the member. Holes shall not be closer
than 2 inches (51 mm) to the top or bottom of the member, or
to any other hole located in the member.Where the member
is also notched, the hole shall not be closer than 2 inches (51
mm) to the notch.

R502.8.2 Engineered wood products. Cuts, notches and
holes bored in trusses, laminated veneer lumber, glue-laminated
members or I-joists are not permitted unless the effects
of such penetrations are specifically considered in the design
of the member.

[JimD]

I googled to try and find some wooden I beam information and did not find any for 12 inch high I-beams. Cutting them is definitely different from cutting into 2x lumber. What I did find was for 16 inch high beams but there were areas that they did not want the OSB cut.

You don't mention spacing but that is a large factor. I cannot tell from your length description what the longest span is. It does not matter how long the beam is, it matters how much distance it spans before there is a support.

I think there is insufficient information to resolve this. Ideally you want some information from the beam manufacturer. You might be able to get something from a local lumber yard. Or you might be better at googling up information than I am. If I did not know for sure it is OK, I would still want to replace some of the lost material in the web. Another layer of 5/8 OSB seems more applicable than 2x lumber, however.

It also matters some what the floor in the bathroom in the affected area is. You are risking more deflection by having the floor joist being less sturdy. For linoleum, this would not matter as much as it would for ceramic tile or stone. In other words, the floor shouldn't fail as in somebody falls to the basement (or the tub does). But it could flex enough to pop up tile.

Jim

[chopnhack]

You might want to use some simpson strong tie screws.


They are routinely used down here to fasten lvl's together.

[Kristofor]

With the engineered I-Beams you can have quite large holes through the webbing so long as they're in the right places.

I'm traveling for work right now so I can't look up the specifics on the ones used in my house, but I have done so in the past. There were specs on the maximum hole size, hole location, and I believe how close 2 holes could be to one another.

Here's something I came across trying to search for the info from memory (these are not what I have).

http://files.buildsite.com/dbderived...ived296039.pdf

You can see how much of the webbing is removed from these from the factory. They may be beefier than what you or I have, but the diagram at the bottom is very similar to what the manufacturer of mine had available (sans pre-cut holes of course).

[jking]

I googled to try and find some wooden I beam information and did not find any for 12 inch high I-beams. Cutting them is definitely different from cutting into 2x lumber. What I did find was for 16 inch high beams but there were areas that they did not want the OSB cut.
Jim

12 inch I-joists are commonly identified as 11-7/8". If the OP is able to look at the joist & find the manufacturers name, the information can likely be found on the mfg's website. Trus-Joist, for example, allows holes up to 6-1/2 inches depending on how close to supports. More information is definitely needed.