| Author |
Message |
Brian Payne, AIA
Senior Member
Username: brian_payne
Post Number: 11
Registered: 01-2014
| | Posted on Tuesday, February 11, 2014 - 09:33 am: |    |
Anyone have any thoughts on a efficient way to coordinate what items are to receive blocking. For restroom accessories, I usually add OFCI items to 10 2800 in order to be able to enforce the mounting requirements, but there are plenty of items that don't quite make sense to place there that need blocking. Sharps containers, hand sanitizer, and glove boxes are typical healthcare items that are often "spec homeless". What I am not a fan of is a typical blocking detail that places the responsibility on the contractor to magically know the weights and mounting requirement of items he is not providing. Thoughts? |
Steven Bruneel, AIA, CSI-CDT, LEED-AP, EDAC
Senior Member
Username: redseca2
Post Number: 434
Registered: 12-2006
| | Posted on Tuesday, February 11, 2014 - 12:44 pm: | |
In California, hospital projects are reviewed by the state agency OSHPD, which has strict requirements for anchorage details, so we get plenty of time as Architects to "practice" getting this right.
The best way to document and capture the scope of the backing requirements is by setting up a standard drawing sheet showing typical mounting heights. Usually a floor line datum with each item drawn with semi-fidelity in elevation with the appropriate dimension shown (to the top, the coin slot, or whatever is the driving dimension). We then show the backing as a dashed line (meaning it is behind the wall finish) and then a note, "Backing Type 1,2,3...).
The interior wall framing standard details sheet then includes a backing type schedule. The schedule shows a plan detail and a load diagram.
A drawing I have open on my desktop right now has three:
16-gauge, 6-inch wide flat piece of sheet metal screwed to 16-inch on center 20 gauge studs calculated to support 15 pounds lateral and 100-pounds vertical. This one will handle most of the small stuff you mentioned.
16-gauge, 6-inch stud track notched to fit to 16-inch on center 20 gauge studs calculated to support 100 pounds lateral and 500-pounds vertical.
16-gauge, 6-inch wide flat piece of sheet metal notched to fit to 16-inch on center 16 gauge studs calculated to support 170 pounds lateral and 760-pounds vertical.
Of course there are also custom details needed for more specialized needs.
Elsewhere here at 4specs discussion forum there is a long conversation about Basis of Design. My most frequent use of "Basis of Design" is where we note a product or two as the basis of design "for spatial layout and anchorage details and calculations approved by OSHPD". |
Brian Payne, AIA
Senior Member
Username: brian_payne
Post Number: 12
Registered: 01-2014
| | Posted on Tuesday, February 11, 2014 - 08:00 pm: | |
First, thanks for your thorough response, but here are the challenges that I see.
1. The standard mounting height sheet is usually a static detail. In my experience it rarely gets updated to reflect the actual items in the project.
2. Even when updated the items shown may be significantly different then that which get's installed, especially in a competitive bid project or OFCI situation.
3. Dimensioning to the "appropriate" location for AHJ/ADA purposes may be helpful to get a permit, but many cut sheets for these items do not have a dimension from the "appropriate" dim to the anchor point. Is the guy installing the strap going to figure it out, so months later the item actually hits the backing? 3 inch fudge factor does help though.
3. I'm conflicted somewhat about the specific details as well. We trust the framer to right size the studs based on the lateral performance requirements, unsupported height, and minimum gauge specified. Why is it that we don't also prescriptively trust him to make sure those same items deflecting on his wall also don't fall off of it? Would it increase/reduce field issues if we did handle backing as delegated design as well?
4. How is the framer supposed to know the weight of things like shelving systems that may contain heavier items or equipment?
By asking these questions I don't mean to suggest I have an answer. I know personally, I prefer a written schedule on the drawings for mounting heights. It works much more seamlessly with Revit and auto edits itself as items are added to or removed from the project. I do specify a minimum backing material width to make sure the contractor gives himself enough fudge factor when he misses an anchor point.
My main concern though is with OFCI items that I may have limited knowledge about. Does OSHPD have a list of items required to have backing besides gypsum board? Obviously new items added to existing facilities probably would not have backing.
Lastly, am I overthinking this?  |
spiper (Unregistered Guest)
Unregistered guest
| | Posted on Wednesday, February 12, 2014 - 10:33 am: | |
are you over thinking this? Yes you absolutely are, assuming you have a good carpenter sub on the job. if you have a poor carpenter sub then you could spend all day thinking about it and still not be doing enough. We struggle with the same issues and we still illustrate standard mounting heights for various elements as well as provide a laundry list of items that require backing. This system is problematic and the potential for omissions requires constant coordination. long story, short; I have no answers either but at least your misery has some company.
On a related subject; we have been specifying Danback backing by Dietrich and have gotten some good feedback. What is the perception of this elsewhere in the country? |
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