The Architect drawings call for Type X Gyp Board in partitions that are not required to be fire rated, the GC wants to substitute with standard Gyp Board of same thickness. Is this acceptable? Is Type X stronger?
This might be more info than you want, but here it is
Regular gypsum board, after water
is driven off by heat from a fire,
reduces in volume, develops large
cracks in the board, and eventually
fails. A 5/8 inch regular gypsum wallboard
panel exposed to 1850F., will
fail in 10 to 15 minutes. By extrapolation,
a 1/2-inch board would probably
fail in 10 to 12 minutes.
Type X has a glass fiber reinforced
gypsum core. The fibers reduce the
extent and severity of cracks in the
board when exposed to flame and
heat, thus increasing the time it performs
without failure. Tests show that
Type X board, exposed to the same
1850 heat will remain effectively in
place for 45 minutes. It, too, ultimately
fails
Dewayne, appreciate the quick response, but my client does not need fire resistance, the question is other than fire resistance is Type X better than Standard?
Jerome,
“Type X has a glass fiber reinforced
gypsum core.”
This should make it stronger.
My understanding is that regular gypsum board is 1/2" and Type X is 5/8". This has to do with efficiencies in manufacturing. At one time, you could get either in either thickness, but several years ago the manufacturers decided to standardize. 5/8" regular would therefore now be a special order, and probably end up costing more than 5/8" type x.
It’s been several years since I have been involved in writing Division 09 specs, so you should verify this information from one of the major gypsum companies, National or USG. Let me know what you find out, if this is still the case.
“should make it stronger” is a reasonable assumption, but performance also depends on the gypsum board, gypsum to fiber bond, paper faces, etc.
Test data would be a more useful. I am sure the major gyp board companies can answer.
But first, what type of strength is customer looking for?
- Flexural
- Fastener head pull-over.
- Shear
- Wet strength
- Impact
- Crushing
Did architect have a bad experience that he/she is trying to avoid?
Let us know what you find out as I am interested.
It’s easy to overthink this. On several of our projects, the architect wanted to use Type X for all partitions because there was less field management and inspection required to make sure that the correct type gypsum board was installed in each partition. Having just one type of board solved this problem by avoiding it. The cost savings in the GC’s field management outweighed any additional material and labor costs involved with using Type X board everywhere–though this may vary in different locations.
Another consideration is that 5/8" board provides higher STC ratings–is that an issue for the architect?
My thoughts, too, Dave.
George, 1/2 inch Type X is available. I recall the rumor, several years ago, that non-rated 5/8 inch board was going to be discontinued. Apparently, the economics don’t justify doing so.
Sheldon,
it’s still available:
In So Florida its always about $$$, Architect called for Type X everywhere because it is a condo and more sound control is always better, the UL Assembly calls for 5/8 in. not 1/2 in. The Developer wants to reduce cost anyway he can, so he has asked the GC to cut corners and reduce cost. The bigger problem is going to be if all these changes are going to be documented in a record set, Florida Statutes require that the Developer turn over to the Condo Association a set of documents that depict the actual construction, however this is barely ever done.
When problems start developing with construction defects questions will be asked as to why construction in place does not match the drawings. Condo home owners do not care about the Developer wanting to save $$$, they want to know if they have been short changed.
These days sound control litigation is more likely than mold and mildew. The difference in gyp board thickness could certainly backfire on the Developer and the Architect.
Keep on responding, I have to leave the computer and put my shutters in place before the rain starts…yes I am in Broward County and we are going to have a visit from a storm called Matthew in 24 hours, so much fun I can not tell you.
Gas stations starting running out of gas last night.
Like Dave above, we use Type X for everything that doesn’t require Type C. I was told by a contractor years ago that the cost difference between 1/2 and 5/8 X is nothing compared to the redo if some idiot puts 1/2 where the 5/8 belongs. 5/8 definitely gives better STC than 1/2. University clients of ours require 5/8 everywhere.
Have the GC tell developer to hire 3rd party inspector to continuously monitor installation so 1/2-inch isn’t installed on rated partitions? Or better yet, GC’s change order proposal should include such inspection…that should more than offset cost savings (if any) for using 1/2-inch board?
Don’t be confused between Regular 5/8" and the newer Ultralight 5/8". The Ultralight is 30% lighter which is great on installers, but that 30% in weight will have a negative effect on acoustical STC. (Which as far as I know has yet to be substantiated.)
Be careful that the contractor is not using ultralight for non-rated walls. We are doing an office remodel right now, and the contractor is using 1/2" ultralight for the sound/dust partition. Not good.