# Drywall thickness



## fiore22 (Jun 11, 2006)

I'm going to call the building department on this tomorrow. However, I thought I might get some clarification on it now. I got a drywaller telling me it's ok to put 1/2" on the exterior wall of a home in Los Angeles. I say it needs to be 5/8's. 
Does anybody here know for certain what the thickness of the drywall needs to be on exterior walls for the city to pass on it. The exterior is stucco, no sheeting.


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## kgphoto (May 9, 2006)

What do the plans say? What is the rating of the house? Type 1, 2, 3, 4 or 5 with what hour rating? What is the stud spacing? Single or two story?

The likely hood is that 1/2 is fine, but 5/8 would be better.

If you can answer the questions above, I can look up the relevant code section.


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## fiore22 (Jun 11, 2006)

kgphoto said:


> What do the plans say? What is the rating of the house? Type 1, 2, 3, 4 or 5 with what hour rating? What is the stud spacing? Single or two story?
> 
> The likely hood is that 1/2 is fine, but 5/8 would be better.
> 
> If you can answer the questions above, I can look up the relevant code section.


Single story residential. No plans regarding the remodel that specify the drywall. It's all wood construction with stucco exterior. Thanks in advance.


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## Chris Johnson (Apr 19, 2007)

Generally 1/2" drywall for single family is acceptable, however, we are both in California and most houses I see are framed 24" o.c., 5/8" makes sense on the walls to help with the strength of one leaning/falling/pushing on it, and 1/2" on a trusses or the underside of floorjoists on 24"o.c. has a habit of sagging which is not noticable until the light hits it a certain way and then it can look like the Pacific Ocean. I'm also betting that your house in question has numerous amounts of HD's, straps, connection plates, etc, all surface mounted creating an uneven wall surface, 5/8 helps 'float' this out and not be as visable.

Use the 5/8" as you want.


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## RockStar (May 11, 2006)

*Stick with the plans*

Your plans were spec-ed with 5/8 and usually for a reason. Perhaps to meet an ASTM, BOCA, or local code that meets the type of building requirements. 

If it says 5/8 and you allow 1/2 even if you don't get caught now, you could be liable if something happens down the road. If you do get caught right away you could be forced to tear it all down and replace it with the 5/8. Is it really worth it?

Check with the engineer and or architect before making any changes.

There are too many reasons 5/8 may have been spec-ed to speculate on why its written in there. 

Good luck:


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## kgphoto (May 9, 2006)

Still not enough information to answer your question accurately.

Here is the table that show 1/2 or 5/8 is acceptable depending on conditions.

Unfortunately, it is a PDF document and I don't know how to paste it so the formatting holds.



TABLE 25-G—SINGLE-PLY GYPSUM WALLBOARD APPLIED PARALLEL (||) OR PERPENDICULAR (⊥) TO FRAMING MEMBERS
THICKNESS
OF GYPSUM
MAXIMUM
SPACING OF
FRAMING
MEMBER1
(Center to
LONG DIMENSION OF
GYPSUM WALLBOARD
SHEETS IN RELATION TO
MAXIMUM SPACING OF
FASTENERS1
(Center to Center)
(inches)
WALLBOARD
(inch) PLANE OF
FRAMING
Center)
(inches)
DIRECTION OF FRAMING
MEMBERS × 25.4 for mm NAILS2—TO WOOD
× 25.4 for mm
SURFACE × 25.4 for mm || ⊥ Nails3 Screws4 × 25.4 for mm
Horizontal
16 P P
7 12 N 13 13/ ” l 19/ ” h d 0 098” di t
1/
24 NP P
No. gage, 8” long, 64” head; 0.098” diameter,
2 11/4” long, annular ringed; 5d, cooler (0.086” dia., 15/8”
Vertical
16 P P
8
16
4 0.086 8
long, 15/64” head) or wallboard ( 0.086” dia., 15/8” long,
9/ ” head) nail
24 P P
12
g 64 ) 8 g
32” nail.
Horizontal
16 P P
7 12 N 13 15/ ” l 19/ ” h d 0 098” di t
5/
24 NP P
No. gage, 8” long, 64” head; 0.098” diameter,
8 13/8” long, annular ringed; 6d, cooler (0.092” dia., 17/8”
Vertical
16 P P
8
16
8 0.092 8
long, 1/4” head) or wallboard ( 0.0915” dia., 17/8” long,
19/ ” head) nail
24 P P
12
g 4 ) 8 g
64” nail.
Nail or Screw Fastenings with Adhesives (Maximum Center to Center in Inches)
× 25.4 for mm
(Column headings as above) End Edges Field
1/2
Horizontal
16 P P 16 16 24
1 5
or
5/
24 NP P 16 24 24 As required for 1/2” and 5/8” gypsum wallboard, see
above
8 Vertical 24 P P 16 24 NR
above.
NOTES: Horizontal refers to applications such as ceilings. Vertical refers to applications such as walls.
|| denotes parallel.
⊥ denotes perpendicular. P—Permitted. NP—Not permitted. NR—Not required.
1Acombination of fasteners consisting of nails along the perimeter and screws in the field of the gypsumboardmay be usedwith the spacing of the fasteners shown
in the table.
For fire-resistive construction, see Tables 7-B and 7-C. For shear-resisting elements, see Table 25-I.
2Where the metal framing has a clinching design formed to receive the nails by two edges of metal, the nails shall not be less than 5/8 inch (15.9 mm) longer than
thewallboard thickness, and shall have ringed shanks.Where themetal framing has a nailing groove formed to receive thenails, the nails shall have barbed shanks
or be 5d, No. 131/2 gage, 15/8 inches (41 mm) long, 15/64-inch (6.0 mm) head for 1/2-inch (12.7 mm) gypsum wallboard; 6d, No. 13 gage, 17/8 (48 mm) inches
long, 15/64-inch (6.0 mm) head for 5/8-inch (15.9 mm) gypsum wallboard.
3Twonails spaced 2 inches to21/2 inches (51mmto 64mm) apartmay be usedwhere the pairs are spaced 12 inches (305mm) on center except around the perimeter
of the sheets.
4Screws shall be long enough to penetrate into wood framing not less than 5/8 inch (15.9 mm) and through metal framing not less than 1/4 inch (6.4 mm).


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## kgphoto (May 9, 2006)

Do an online search for the LA City Municipal code and look up section 91-25. the details are there.


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## fiore22 (Jun 11, 2006)

kgphoto said:


> Do an online search for the LA City Municipal code and look up section 91-25. the details are there.


If you have a link to a specific site I would be very grateful.


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## Dustball (Jul 7, 2006)

kgphoto said:


> Do an online search for the LA City Municipal code and look up section 91-25. the details are there.


I'm looking at it right now and the lowest 91.xxx code is 91.101.1 Plumbing starts with 94.100.0 I don't see 91.25 anywhere.

http://www.amlegal.com/los_angeles_ca/


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## kgphoto (May 9, 2006)

Here's the text right from the document you sited.

DIVISION 25
GYPSUM BOARD AND PLASTER

(Division Amended by Ord. No. 172,592, Eff. 6/28/99, Oper. 7/1/99.)

Section

91.2500 Basic Provisions.

91.2513 Shear-resisting Construction with Wood Frame.
SEC. 91.2500. BASIC PROVISIONS.

Heres the link from the top of the page. The section is about 1 inch down the scroll bar.

http://www.amlegal.com/nxt/gateway.dll?f=templates&fn=default.htm&vid=amlegal:lamc_ca


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## Dustball (Jul 7, 2006)

I don't know why I was looking for plumbing- had my mind set on a different thread.

There you go fiore22- the answer you need.


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## fiore22 (Jun 11, 2006)

kgphoto said:


> Here's the text right from the document you sited.
> 
> DIVISION 25
> GYPSUM BOARD AND PLASTER
> ...


Thank you...this was very helpful.


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## kgphoto (May 9, 2006)

What did your building department say?


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