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Bathroom Grabrail Support

Bathroom Grabrail Support

Bathroom Grabrail Support

(OP)
I am working a job where the Arch. has asked the metal stud installer to provide "blocking" between the studs to support ADA bathroom grabrails. My understanding is that the attachment must resist 250lbs in any direction. The Arch.has asked that they use light gage strapping screwed to the face of the studs. The studs are 19 mil thick - basically 25 ga but they are called 20ga, ahem, "equivalent" due to the use of high-strength steel.

I told them it is not possible for me to make strap work in that situation unless it is merely there to keep the grabrail from falling to the ground with a 250 lb load.

I recommended heavier studs and wood blocking but the Arch. claims that strapping is their standard detail.

Has anyone been involved with something similar?

RE: Bathroom Grabrail Support

I have NOT been involved in specifying light gage strap for "blocking", nor would I.

Insist on the wood or at least steel stud blocking.

RE: Bathroom Grabrail Support

I would think a piece of steel stud, turned with its flat side toward the bathroom, would be the simplest and cheapest solution. How old is this architect? What does he think he is saving?

RE: Bathroom Grabrail Support

(OP)
That's what I mentioned to the contractor. However, there is still the issue of connecting to the wimpy flange of a 25 ga stud. I guess you could install some clips so it can attach to the web but still seems like you are counting on drywall to pick up the slack.

RE: Bathroom Grabrail Support

The general contractor i deal with regularly uses minimum 22 gage CFS studs in partition walls with a minimum 20 gage stud at door jambs.

In even light structural situations i would insist on a 20 gage studs to support the 20 gage blocking.

We're only talking about (2) studs in every bathroom regardless of how many bathrooms there are!

RE: Bathroom Grabrail Support

A track notched at the studs is common backing for grab bars. Many stud manufactures supply tracks notched at 16" OC for backing applications (here is one example http://www.clarkdietrich.com/products/backing-syst...). We typically use 6" x 16 ga tracks (for hospitals), but you may be able to use smaller.

RE: Bathroom Grabrail Support

There is no conceivable acceptable technical explanation for using 25 gauge studs in lieu of 20 gauge studs. The controlling factor is almost always deflection, and whatever the steel strength, the modulus of elasticity is the same.

RE: Bathroom Grabrail Support

Hokie:
You said “There is no conceivable acceptable [engineering] explanation for using 25 gauge studs in lieu of 20 gauge studs.” You missed the word ‘engineering’ btwn. the words ‘acceptable’ and ‘explanation.’ Today’s contractor’s mantra is.... never do it right, if you can do it wrong and save a couple pennies per stud or piece of blocking. That’s how they make up for some of their laziness in putting their bid together. Think of all the material savings in using the 25ga. studs, and they are readily available, on sale, at any big box store. They don’t have to worry about pre-ordering the approx. right quantity, from a real materials supply house.

XR250:
Remember, every blocking to stud connection must essential be able to take the 250 lb. loading, given that you don’t really know where the grabrail connection will be.

RE: Bathroom Grabrail Support

dhengr,

Fixed that. I used "technical" instead of "engineering", just because I don't like to use the word "engineer" as anything other than a noun.

RE: Bathroom Grabrail Support

(OP)

Quote (dhengr)

Hokie:
You said “There is no conceivable acceptable [engineering] explanation for using 25 gauge studs in lieu of 20 gauge studs.” You missed the word ‘engineering’ btwn. the words ‘acceptable’ and ‘explanation.’ Today’s contractor’s mantra is.... never do it right, if you can do it wrong and save a couple pennies per stud or piece of blocking. That’s how they make up for some of their laziness in putting their bid together. Think of all the material savings in using the 25ga. studs, and they are readily available, on sale, at any big box store. They don’t have to worry about pre-ordering the approx. right quantity, from a real materials supply house.

XR250:
Remember, every blocking to stud connection must essential be able to take the 250 lb. loading, given that you don’t really know where the grabrail connection will be.

The manufacturer calls them "20ga equivalent" because they get the same limiting heights taking into account composite action with the sheetrock. This must be a function of fastener shear as the shear (and pullout) values for the high-strength steel, 19mil studs are similar to those of the 33ksi, 20 ga studs. It still does not address the other crappy aspect of 19mil studs - such as flange bending and web crippling.

Thanks for everyone's insight.

RE: Bathroom Grabrail Support

As professional engineers, we need to be the authority determining what is "equivalent" or not. The use of yield strength is nowadays often overemphasized, to the detriment of serviceability.

RE: Bathroom Grabrail Support

Like it or not, the International Building Code section 2508.1 references ASTM C754 for steel framing for partitions. And, this standard includes 18 mil studs. So, there are a lot of wimpy studs being installed in the US. My only experience with wimpy studs is when an electrical contractor needed to justify hanging panel boards between studs. If I remember correctly, the cheap-skate low-bid metal framing sub had to double the studs at the panel boards.

RE: Bathroom Grabrail Support

(OP)
Yea, 25ga (18mil studs) are ubiquitous in the industry. I told the arch that they should sheath the entire wall in 3/4" plywood which would give them something stout to attach partitions, sinks etc.
He said they could not afford that.

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