Home>Discussions>INTERIORS>Living Areas & Workspaces>Using epoxy to reconstitute floor joists ???
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milkweed
Using epoxy to reconstitute floor joists ???
milkweed

Floor joists...
utility / plumbing holes that are no longer in use...
can epoxy be used to reconstitute the void?

From what I can gather about joists is that the high side of a joist is in compression and the low side is in tension.

Supposedly epoxy has excellent resistance to compression so it is my assumption then that it would work well for holes on the high side. Please correct me if I am wrong.

Concerning the low side of a joist (that is in tension):
Supposedly some epoxy formulas have high tensile strength, does this mean it could be used on the low side?
or am I confusing tensile strength and tension...

I found this article about some guy embedding a steel reinforcing rod on the low side of a joist:
http://www.westsystem.com/ss/beam-me-up-2/
in this article he does that to a supplemental joist, but the manufacturer that has this project posted has a suggested steps of how to do the same to a joist that is already in place... except that the reinforcing rod does not extend onto the support beam/sill plate because the joist is already in place.
Would a project like this really add resistance to tension in a joist above what the wood already provides?

I have also seen pictures of voids in lumber being mended with embedded stainless steel helical bars and epoxy. Could something like this restore some integrity to low side voids in joists?

A. Spruce
Re: Using epoxy to reconstitute floor joists ???
A. Spruce

Why not just sister the joist instead of using epoxy? Faster and easier if you ask me. Also, unless the notching is beyond allowable tolerances, why worry about the voids at all?

ed21
Re: Using epoxy to reconstitute floor joists ???
ed21

I would ask how big are the holes and where are they located in the joist. Generally holes should be close the the middle of the joist not over a certain size and not in the middle third of the span. All the building codes cover it. This info should be available on-line.
Sistering a joist is probably the easiest, cheapest and best way to repair a wood joist.
You are correct about the compression and tension load in a joist.
I've never heard of repairing joists with epoxy, not to say it couldn't be done. I've used epoxy plenty and what you mention wouldn't be on the list of things I would do.

milkweed
Re: Using epoxy to reconstitute floor joists ???
milkweed

> All the building codes cover it.
Whoever drilled and cut through the joists did not follow the building code.
About half of the basement was finished by the previous owner.
None of the cuts that I see in the unfinished portion are according to code.
I bought the house with the intention of renovating it so it is not a surprise to me.
I knew the joists were this way.

Below both bathrooms there are one joist each that is completely severed!
They are being held up by the nails through the subfloor.
The kitchen is like a bowl, so I imagine they did similar work to a joist or two there.

As for the rest of the house,
there are many joists that they drilled holes to take the shortest path for
the electrical lines. Every electric cord has its own holes through the joists,
they did not string more than one electric line through a hole even though the
holes are big enough to support three lines easily. I haven't gotten the laser
level out yet but these joists still appear to be level.

> I would ask how big are the holes and where are they located in the joist.
My question concerning the use of epoxy mostly concerns these joists with holes
for the electric lines. The joists are all 2x10s.
The holes are about an inch diameter and through the lower third of the joists.

> Also, unless the notching is beyond allowable tolerances, why worry about the voids at all?
I am just concerned that I renovate and install new flooring on the main floor
and later the it begins to sag. There is carpet now, but I plan on renovating
with luxury vinyl. I don't think the vinyl is heavy but still heavier than
carpet.

> Why not just sister the joist instead of using epoxy?
As far as the bathrooms and kitchen are concerned I will sister or replace,
but with the rest of the joists that have holes, I think it might be quicker
with epoxy, especially if it turns out they still are level prior to renovation.

ed21
Re: Using epoxy to reconstitute floor joists ???
ed21

Here is a link to the code about holes and notching.
http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_5_par030.htm
I would question whether just filling holes with epoxy would do much to increase the strength of a joist. I'd be more inclined to sister even if it isn't full length as long as you go well beyond the hole/notch and secure it with a good staggered pattern of nails or bolts. Slathering epoxy between joists would certainly help bond the two together, but in all my years of construction I've never seen a structural engineer specify that.

dj1
Re: Using epoxy to reconstitute floor joists ???
dj1

Quote: "I knew the joists were this way"

- At least you admit it. Buying a home "as is" is exactly what you have - as is.

So back to your original question about using epoxy. I agree with ed21, epoxy may fill holes but will not give you what adding sister joists will do.

If you are thinking about adding load, go to johnbridgetileforum and use their DEFLECTION FORMULA to decide whether your joists are good enough or not.

About vinyl: it may not be heavier than carpet, but it depends on what kind of vinyl or carpet.

Can you post pics of the damaged joists?

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