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Multiwall Sheeting Installation Information

Important Considerations

Polycarbonate is both versatile and tough. Use it in place of wired glass and corrugated roofing sheets. Its light transmission, insulation and strength are essential properties for modern conservatories. The ideal conservatory roofing sheet-use also for glazing and insulation on greenhouses, porches and carports or roofing sheds and workshops. Also suitable for insulated cloches and cold frames.

Know Your Roofing Sheets

Most makes of multiwall roofing sheet have a greater thickness in the top wall. This top wall surface normally consists of a co-extruded outer layer of UV absorber that forms a barrier against UV degradation. The protective film on the sheet will indicate this surface and sheets must always be installed with this surface outwards/external.
Roofing sheets will expand and contract as the temperature changes – up to 4mm per metre, in both directions, between mid-winter and high summer. Dark materials expand faster. Allowance must be made for this when fitting. Always lay roofing sheets with the flutes running from the top to the bottom.

Snow Loading

The width of sheeting and spacing of glazing bars must always allow for adverse weather conditions. The weight of the snow load in the area of installation is established by national and regional standards. If in doubt, check with your supplier.

Using Polycarbonate Sheeting with Kents Glazing Bar Systems

Kent’s glazing bars that are fitted down the long edges of each sheet, are designed to allow for expansion. Fix the sheet at one end to allow this movement to take place in a controlled manner.
Seal the flutes of the sheet at the top end with aluminium tape. The bottom end should be finished with ventilated breather tape and covered by the a sheet closure.
Sheets can be fitted vertically, but are normally used for roofs with a minimum pitch of 10 degrees.
The majority of sheets are used at a width of 1050mm. The maximum width depends on the supporting structure. If no cross supports are used then fix 10mm sheets up to 700mm and 16mm sheets up to 1050mm. Where the snow loading is not greater than 60kg/sqm. Please check with us.
10mm sheets glazed at 1050mm wide need support across with width(purlins), at intervals of 1500mm. Wider sheets will need additional supports.
Kent’s glazing bars do not require additional mechanical fixings except where extreme weather conditions are encountered, when the use of a button fixing centrally positioned on to a support in the middle of each sheet is recommended.
Any trimming of the sheets may create swarf in the flutes, which must be removed. This is best dome with a suction type (vacuum) cleaner. Avoid getting moisture in the flutes, at any time.
Leave the protective film on the sheets until installation is complete, folding back only where necessary to expose areas to be covered by the glazing bars, silicone sealant and flashing. This film should then be removed as soon as possible and it is therefore advisable to advance construction of the roof as far as possible before fitting glazing sheets.

Silicones, Flashing & Cleaning

Although polycarbonate is extremely tough and hard wearing, it can be affected by chemical agents. Care must be taken in the choice and use of such items as silicon sealants and flashing which will be in contact with the sheet.
Ploycarbonate sheets should only be cleaned with water and mild detergent, applied with a soft cloth. Never use solvents to remove marks, although paint, whilst still wet, may be removed with white spirit, provided all excess spirit is cleaned off and thoroughly washed down with water. If in doubt-check it out!
Should there be any doubt about the compatibility of any material, check with us.