### Lintel Sag Formula

Posted:

**Sun Jun 27, 2010 11:57 am**
by **pbennett1**

Hey Jerry,

Is there a formula for allowable tolerance of a sagging steel lintel?

### Re: Lintel Sag Formula

Posted:

**Sun Jun 27, 2010 2:48 pm**
by **Jerry Peck - Codeman**

The answer is: It depends.

As in "it depends" on a variety of things. Such as: the species of the lumber, the use, the live load, the dead load, if engineered (such as LVL, I-joist, etc.), and other conditions.

Typical deflection limits, for a sampling of various conditions, might be 1/180, 1/240, or 1/360.

As example, let us take 1/240 ... that means the maximum deflection is 1/240 of the span, if the span is 16 feet (presuming a 16 foot wide garage opening), then the deflection could be 16 feet X 12 inches = 192 inches / 240 = 0.8 inches, or just over 3/4" deflection under a specific set of conditions which would allow for a 1/240 deflection.

How much is allowed in your case? I do not know, however, if you take the maximum deflection allowed for almost any condition ... 1/180 ... and use that, if that is exceeded than ... more than likely ... more than likely it would be a problem. So, let's do the above example using 1/180:

- Using 1/180 with a span of 16 feet, then the deflection could be 16 feet X 12 inches = 192 inches / 180 = 1.06 inches, or just over 1" deflection under conditions which would allow for a 1/180 deflection.

- If it sags (deflects) more than 1 inch for a 16 foot span then it is highly likely that there is a problem as that would exceed the most generous deflection allowance.

### Re: Lintel Sag Formula

Posted:

**Sun Jun 27, 2010 3:17 pm**
by **pbennett1**

Thanks for both replies.

I will be going back tomorrow to retrieve the radon canister.

I did not take any measurements, but just "eyed" it up. The gap between the mortar joint and seems uniform in size, so I really think the "sag" maybe just shrinking mortar, thus an illusion.

PB