Notch?

[John McKenna]

On an exterior wall or load bearing wall... if a notch
in the top plate exceeds 50% of the width then a
metal strap must be installed.... OK, I got that.

But what is the maximum notch that can be cut in
a 2x4 top plate, even with the metal stap added?

I am looking for code reference and cannot find
the answer in the IRC.

Can you cut out 3" of the 2x4 as long the strap is added?
It seems that there should be a limit.

[Mario A. Kyriacou, CHI]

Originally Posted by jmckenna1

On an exterior wall or load bearing wall... if a notch
in the top plate exceeds 50% of the width then a
metal strap must be installed.... OK, I got that.

But what is the maximum notch that can be cut in
a 2x4 top plate, even with the metal stap added?

I am looking for code reference and cannot find
the answer in the IRC.

Can you cut out 3" of the 2x4 as long the strap is added?
It seems that there should be a limit.

John

On outside wall? I have seen them cut on inside load bearing walls for cold air returns 16" and more. This is not a problem if a 2x4 is supporting the joist above.

[John McKenna]

No, my question is HOW DEEP CAN YOU CUT THE NOTCH?

There is only 3.5" in the top plate of a 2x4 wall.

Example: Can you cut a 3" deep notch and leave a
half inch to hold the wall together?

It seems odd that there would be no limitation.
I can't find anything in the IRC that addresses this.

[ckratzer]

John,
When my plumbers or HVAC boys have to notch deeper than 50% I make them "strap" both sides on load bearing walls.On occasion they've had to cut all the way through and I have them "strap" both sides in those instances as well.
On exterior walls we would only strap the inside as the outside is held in line by the sheathing which is already in place .Rarely ,though ,have I ever built a home that required a hole that big on an exterior wall.
On interior load bearing walls if the ceiling joists,(single storey)or floor joists are joined together properly over the bearing wall this will also help keep the wall in line.In addition when the floor joists,(if present) above are sheathed this will prevent movement as well.
I will say that when it comes to a plumbing related notch I won't use straps at all but rather a Bocca plate ( nail guard).They are heavier guage and better than a strap.If I can't get one from a store I have them made by a welder.
Right or wrong I don't know but the codes inspectors haven't questioned it in any instance.
Safe thing to do is ask you local codes admin.

Cheremie

[Carla Horne]

Hi,
it is hard to picture what you mean, normally on an exterior wall the
top plate is doubled. I will assume that in this case it is not.

no photos?

CJ

[John McKenna]

Yes I understand that a metal strap can be added
to the top plate. But it seems odd that a huge
notch would be allowed without limitation in the IRC.

Imagine a 3"x3" notch on an outside wall top plate.
That would only leave half an inch of wood left
after the notch was taken out (because the top
plate is only 3.5" on a 2x4 wall).

Just seems odd that the code does not address
how deep the notch can be ... it just says to
add a metal strap if over 50%. Hmmm.

[Mario A. Kyriacou, CHI]

Originally Posted by jmckenna1

Yes I understand that a metal strap can be added
to the top plate. But it seems odd that a huge
notch would be allowed without limitation in the IRC.

Imagine a 3"x3" notch on an outside wall top plate.
That would only leave half an inch of wood left
after the notch was taken out (because the top
plate is only 3.5" on a 2x4 wall).

Just seems odd that the code does not address
how deep the notch can be ... it just says to
add a metal strap if over 50%. Hmmm.

John

I will tell you what the ONTARIO BUILDING CODE states.

9.23.5.4.[1] TOP PLATES IN WALLS SHALL NOT BE NOTCHED,DRILLED OR OTHERWISE WEAKEND TO REDUCE THE UNDAMAGED WIDTH TO LESS THAN 50mm [2"] UNLESS THE WEAKENED PLATES ARE SUITABLY REINFORCED.

Like I said you can cut the entire top plate with no problem as long as you reinforce the top plate that a joist is resting on.[ on either side]I will try and post a picture of what I'm talking about.

We also have the 2/3 rule if a stud or 2x4 is load bearing [vertical]

[John McKenna]

Thanks....

I can see it up to each person to strengthen the notched
area as needed. The language in the IRC gives no
limitation specifically, that I can find.

I have been around these notches for a long time,
but the question of code came up and I did not know
the exact answer.