S.I. No. 352/1952 - Standard Specification (Gypsum Plasterboard) Order, 1952.


S.I. No. 352 of 1952.

STANDARD SPECIFICATION (GYPSUM PLASTERBOARD) ORDER, 1952.

I, SE?N F. LEMASS, Minister for Industry and Commerce, in exercise of the power conferred on me by subsection (3) of section 20 of the Industrial Research and Standards Act, 1946 (No. 25 of 1946), hereby order as follows :

1. This Order may be cited as the Standard Specification (Gypsum Plasterboard) Order, 1952.

2.—(1) The specification set forth in Part II of the Schedule to this Order is hereby declared to be the standard specification for the commodity described in Part I of the said Schedule.

(2) The said standard specification may be cited as Irish Standard 41: 1952.

SCHEDULE.

PART I.

GYPSUM PLASTERBOARD.

PART II.

SPECIFICATION.

In this specification, the letters I.S., when followed by two sets of numbers, refer to the Irish Standard of which the first is the serial number and the second the year of its promulgation by the Minister for Industry and Commerce.

SCOPE

1. This specification covers the requirements of gypsum plasterboard suitable for use in walls, ceilings or partitions.

COMPOSITION

2. Gypsum plasterboard shall consist essentially of a core of gypsum plaster enclosed between and firmly bonded to sheets of heavy paper. The gypsum plaster used shall be common gypsum plaster conforming to the provisions of I.S. 27 : 1950.

TYPES

3. Gypsum plasterboard shall be of one of the following types :

(a) Gypsum baseboard,

(b) Gypsum lath,

(c) Perforated gypsum lath,

(d) Gypsum plank,

(e) Gypsum wallboard, or

(f) Gypsum recessed-edge wallboard.

DESCRIPTION OF TYPES

4.—(a) Gypsum baseboard shall be gypsum plasterboard of 3/8 in. thickness having surfaces suitable for taking plaster.

(b) Gypsum lath shall be gypsum plasterboard of 3/8 in. thickness having surfaces suitable for taking plaster. The edges shall be such as to obviate the use of scrim.

(c) Perforated gypsum lath shall be gypsum lath having circular perforations of ¾ in. to 1 in. in diameter equally spaced with one perforation for not more than 16 sq. in. of surface.

(d) Gypsum plank shall be gypsum plasterboard of ¾ in. thickness having surfaces suitable for taking plaster.

(e) Gypsum wallboard shall be gypsum plasterboard of ¼ in., 3/8 in. or ½ in. thickness having one surface self-finished or suitable for taking decoration and the other suitable for taking plaster.

(f) Gypsum recessed-edge wallboard shall be gypsum wallboard having shallow recesses along the longitudinal edges such that a uniform surface may be obtained by the application of a suitable filler and tape.

DIMENSIONS

5. Gypsum plasterboard shall be rectangular. The corners shall not vary from the square by more than 1/8 in. in the full width of the board.

The dimensions of each type of gypsum plasterboard, when determined as described in Appendix A, shall conform to the values set out for the type in Table 1. The length shall be subject to a tolerance of ± 1/8 in., the width to a tolerance of ± 1/16 in. and the thickness to a tolerance of ±0·02 in.

TABLE 1—DIMENSIONS

Type

Length

Width

Thickness

ft. in.

ft. in

in.

2

4

Gypsum baseboard

2

6

3

0

3/8

2

8

2

8

3

6

Gypsum lath

3

9

Perforated gypsum lath

4

0

1

4

3/8

4

6

4

8

5

0

6

0

7

0

Gypsum plank

7

6

1

8

¾

8

0

8

6

9

0

10

0

6

0

}

7

0

7

6

2

0

8

0

3

0

Gypsum wallboard

8

6

4

0

¼

Gypsum recessed-edge wallboard

9

0

3/8

10

0

}

3

0

½

11

0

4

0

12

0

WEIGHT

6. The weight of gypsum plasterboard per thousand sq. ft. when determined as described in Appendix C, shall be within the limits set out in Table 2 for each thickness of plasterboard.

TABLE 2.—WEIGHT

Thickness in.

Weight in lb. per 1000 sq. ft.

¼

900 to 1200

3/8

1300 to 1800

½

1800 to 2400

¾

2700 to 3600

TRANSVERSE STRENGTH

7. The breaking loads of the plasterboard shall be determined in a direction parallel to the length of the plasterboard and in the perpendicular direction, as described in Appendix D. The breaking loads for each type of plasterboard shall be not less than the values set out for the type in Table 3.

TABLE 3.—MINIMUM BREAKING LOAD

Type

Thickness in.

Breaking load in lb.

Parallel to length

Perpendicular to length

Gypsum baseboard

3/8

38

26

Gypsum lath

3/8

43

30

Perforated gypsum lath

3/8

40

28

Gypsum plank

¾

150

90

Gypsum wallboard and Gypsum recessed-edge wallboard

{

¼

60

30

3/8

90

40

½

120

50

QUALITY AND FINISH

8. Gypsum plasterboard shall be free from imperfections or deleterious constituents which would render it unsuitable for its purpose. The plasterboard shall be true and solid throughout.

MARKING

9. Gypsum plasterboard shall be marked clearly with the name or mark of the manufacturer and with the type of the plasterboard.

TESTING

10. The manufacturer shall satisfy himself that the plasterboard conforms to the requirements of this specification.

If the purchaser requires independent tests, these shall be carried out in accordance with this specification and the cost of the tests shall be borne

by the vendor in the event of results showing that the plasterboard does not comply with this specification,

by the purchaser in the event of results showing that the plasterboard complies with this specification.

SAMPLING

11. For the purpose of testing conformity of gypsum plasterboard with the requirements of this specification, samples shall be taken at random from the consignment and shall consist either of half of one per cent. of the total number of plasterboards or seven plasterboards, whichever is the greater.

Appendix A

DETERMINATION OF DIMENSIONS

Length and Width : Measurements of the length and width shall be carried out on each of 6 plasterboards. The length shall be measured at 3 places evenly spaced across the board and the average of the 3 measurements shall be taken as the length of the board. The width of the plasterboard shall be determined in a similar manner.

Thickness : Measurements of thickness shall be carried out on 6 plasterboards. The thickness shall be measured with a micrometer to an accuracy of ±0·01 in. The contact surface of the micrometer shall have a diameter of not less than ¼ in. The sample shall not be deformed when the thickness is measured. Readings shall be taken at 6 places near each end of the plasterboard and equally spaced across the full width of the board. No readings shall be taken within 1 in. of a cut end nor within 3 in. of a folded edge. The average of the 12 readings for each board shall be determined and the average for the 6 boards shall be taken as the thickness of the plasterboard.

Appendix B

PREPARATION OF SPECIMENS

Two specimen pieces measuring 16 in. ±1/8 in. by 12 in. ±1/8 in. shall be cut from each of 6 plasterboards. Of the 2 specimens taken from each plasterboard, one shall be cut with the longer dimension parallel to the length of the plasterboard but shall not include a folded edge and the other shall be cut in the perpendicular direction. In the case of perforated gypsum lath the specimens shall be cut so that the shorter of the two centre lines of the specimens runs directly across a line of perforations.

The 12 specimens shall be conditioned for testing by drying them to constant weight in a well ventilated oven at a temperature of 35°C. to 40°C. The specimens shall be regarded as dried to constant weight when the weight determined after conditioning for a further period of 30 minutes is found to be unchanged. The weighing shall be carried out to an accuracy of ±0·1 per cent. of the weight of a specimen.

Appendix C

DETERMINATION OF WEIGHT

Twelve specimens prepared and conditioned as described in Appendix B shall be weighed. The average of the 12 weighings expressed in pounds per 1000 sq. ft. shall be taken as the weight of the plasterboard.

Appendix D

DETERMINATION OF TRANSVERSE STRENGTH

Each one of 12 specimens, prepared and conditioned as described in Appendix B, shall be simply supported on parallel supports rounded to a radius of 1/8 in. to 3/8 in. and spaced at 14 in. centres. Where the plasterboard has folded edges the surface which has a double thickness of paper along the folded edges shall be placed upwards.

The load shall be applied evenly at the centre of the board by means of a bearing rounded to a radius of 1/8 in. to 3/8 in. parallel to the end supports. Specimens of perforated gypsum lath shall be placed so that the centre bearing runs directly above a line of perforations. The load shall be applied at a rate of 30 to 70 lb. per minute.

The breaking load for each of the 12 specimens shall be determined. The average value for the breaking load of the 6 specimens which were cut parallel to the length of the plasterboard shall be determined and taken as the breaking load parallel to the length. The average value for the 6 specimens which were cut in the perpendicular direction shall also be determined and taken as the breaking load perpendicular to the length.

GIVEN under my Official Seal this 1st day of December, 1952.

(Signed) SE?N F. LEMASS.

Minister for Industry and Commerce.