The perfect Shelter
Cement Roofing Sheets
The Visaka Timeline
Visaka’s priority is quality and strength. Therefore, it prides itself on excellence, superior technology, and most of all, the professional expertise that goes into making its products. Visaka’s products are undisputed recipients of appreciation for their affordability and durability. Visaka’s state-of-the-art Fibre Cement plant is a fully automated factory that incorporates new-age, sophisticated technology, ensuring consistency in physical properties and strength that surpasses the ISI standards.
|Year of Establishment
|| Established in 1981, our first factory commenced production of cement sheets in 1985.
|Production Quantity (Annual)
||Initial Capacity (1985)- 36,000 tons Current Capacity (2015)- 8,02,000 tons
||8 plants across India
||Procured from renowned Engineering groups, our machinery and equipment are top-of-the-line, undergoing periodical inspection and maintenance.
||FY: 2015-16 About Rs. 1,000 crores
ISI SPECIFICATION TECHNICAL DATA
|Standard lengths in (Metres)
||3.00, 2.75, 2.25, 2.00, 1.75, 1.50
||Tolerance (in mm)
+5 -10 +Free -0.5 +6 -2 +3 -5 +10 -5 +10 -5
|Maximum unsupported overhang
||Maximum Purlin Spacing for roofing
||Maximum Rail spacing for Vertical cladding
||ZB:75 cm3 ZT:85 cm3
||Moment of Rupture
||Running Metres per tonne
|Minimum End lap
||150 mm (for slopes 180 and above)
ECONOMICAL SIZING & ESTIMATING FOR
VISAKA CORRUGATED SHEETS & ACCESSORIES
- Let us assume the slope length is L metres
- To cover this length, a minimum of N number of sheets are; where N = L - 0.200/2.8 (a whole number)
- Maximum lap loss is M metre Where M = (N-1) x 0.200
- Maximum sheet length required is P; where P = L + M => L + (N-1) x 0.200 (rounded off to next digit divisible by 0.25)
- Once P is obtained, sizing should be done keeping the number of sheets at N
- Check if the slope can be covered by (P - 0.25)
- Check that the number of purlins does not exceed - K; where K = L - ( a1 + a2) / 1.40 + 1 (a whole number); where a1 = distance between the eaves purling and the eaves edge in - Metre; where a2 = distance between the eaves purling and the eaves edge in - Metre.
For Wall Cladding :
Most economical length is 1.75 M, which allows a rail spacing of 1.6 M.
For both roof and wall cladding, the number of sheets in a particular row N = L - 0.04 / 1.01 (a whole number); where L = length of the shed in metres.
ESTIMATING ROOFING ACCESSORIES
The covering capacity of the following Roofing Accessories corresponds to the width of the sheets :
- All Ridges (number in pairs)
- North light curves (in numbers)
- Apron pieces (in numbers)
- Eaves Filler pieces (in numbers)
The fixing procedure should be followed as per is 3007/1964: code of practice for laying of non-asbestos cement sheets - part 1, corrugated sheet:
- Before laying of sheets check the purlin spacing and the length of the sheets to ensure that the sheets’ arrangement will provide the required end lap (min. 150 mm as shown in fig 5) and the specified overhang at eaves (max. 300 mm) and at the ridge (typically 75 mm).
- The sheets are to be laid with the smooth side facing the weather.
- For left to right fixing, start at eaves with sheet ‘a’ - (fig. 1) to the purlin with downward corrugation on the left and upward corrugation on the right, so that the downward ridge of the next sheet can site on it.
- Next, place the sheet ‘b’ which is mitred at the bottom right-hand corner in the manner shown in fig 2.
- All other sheets in this slope, including ridge sheet ‘c’ should be fixed similarly.
- Start the next tier with sheet ‘d’ which is mitred at the top left-hand corner. Make sure that the side lap (1/2 corrugation min.) is correct. Mitring is done, as shown in fig. 3.
- Continue with sheet ‘e’ which is mitred at the top left-hand corner and bottom right-hand corner.
- At the ridge, fix the sheet ‘f’ which is mitred at the bottom right-hand corner.
- Fix ‘g’ & ‘h’, which are mitred on the top left-hand corner.
- Fix ‘i’ without mitring (whenever four sheets meet at a lap joint the intermediate two sheets are to be mitred).
- The bolt should pass through the second and last corrugations, i.e., the bolt distance between two successive sheets should be 279.4 mm (fig 4.)
- For hook blots with a diameter of 8mm (conforming to is 730-1978) - a hole of 10 mm diameter should be drilled (never punched), on the crown of the corrugation.
- A bitumen or GI washer should be used while fixing the sheet with hook blots.
- Hook bolts should not be tightened too tightly.
- The sheets should be fixed with hook bolts at intermediate purlins.
- Mitring or cutting of sheets should be done with an ordinary carpenters saw only.
- Always use a cat ladder during installation for safety and better results.
FIXING OF VISAKA AS-10 SERRATED ADJUSTABLE RIDGES
- Commence from the right-hand edge - lay a few inner rolls r1: the rolls should sit flush with the whole sheets in a straight line (fig. 6).
- Commence laying r2 (outer rolls) - on the opposite slope and in the same direction of r1, so that the small serrations rest with the side lap of the sheets, ensuring a snug sitting of r2 over the roofing sheets and also staggered jointing between r1 and r2.
- The ridge is secured with the same bolt used on the roofing sheets at the right purlin.
"Visaka Towers", 1-8-303/69/3, S.P.Road, Sec-bad-003.
Tel: 091-040-27813833, 27813835
REGD.OFFICE & FACTORY : (A.C.DIVISION I)
|Survey No. 315, Yelumala Village, R.C.Puram Mandal, Medak Dist-502 300(A.P)
FACTORY : (A.C.DIVISION II)
|Behind SUPA Gas, Manikantam Village, Paramati - Velur Taluq, Namakkal Dist - 637 207. Tamil Nadu.
FACTORY : (A.C.DIVISION III)
|Plot No. 11& 12, 18 to 21 & 30, Changsol Mouza, Banki Bundh, GP No: 4, Salboni, West Midnapur, West Bengal - 721 101 Tel: 03227- 285852 / 285851
FACTORY : (A.C.DIVISION IV)
|No. 27/1, G. Nagenhalli Village, Kora Hubli, Dist & Taluk : Tumkur, Karnataka. Tel: 0816-3090393
FACTORY : (A.C.DIVISION V)
|Village Kannawan, P.S. Bacharawan Tehsil : Maharaj Ganj, Raibareli Dist, U.P - 229 301