Many modern homes have extensions of one sort or another. Porches, car ports, sun lounges or other small extensions of the house often make use of PVC roofing. Over time, the roofing may become worn or damaged and need repairing or replacing. Alternatively, if you are thinking of adding such an extension to your home you might well be contemplating adding a corrugated PVC roof as the finishing touch. This is a brief guide on the best method for installing corrugated PVC roofing.
• Clear PVCu corrugated sheets are supplied in 1. 8, 2. 4 or 3 metre lengths x 660mm wide.
• There are mini-profile sheets with a shallower roof corrugation also available from major Builders’ Merchants Stores in a sheet size of 2. 4 metres x 660mm wide.
• Corrugated screws and PVC screw washer sets.
• PVC corrugated eaves fillers.
• Exterior cladding for a professional looking finish to the roof, canopy or car port.
• Wooden joists for canopies, car ports, garages, building roofs and lean-to’s, and wooden support purlins.
Power tools often make light work of even the toughest job. Cutting down on the time it takes to complete a job and making your life easier. For this job we recommend the following power tools:
• Power drill, drill bits and driver for fixing corrugated screws through PVCu corrugated sheets into roof joists and purlins.
• An electric power saw for cutting clear, corrugated PVCu sheets, and timbers and purlins to size.
Clear PVCu roof supports:
All corrugated, clear PVCu sheets should be spaced and placed at 600mm centres and, where mini profile PVCu sheets are applied, placed at 500mm centres. A minimum slope of at least 5 degrees is recommended to achieve a rainwater run-off, but I would advocate you plan towards a 10 degree slope for maximum rainwater run-off.
When any person is working on erecting and fixing large, clear PVCu roof sheets to canopies, car ports and lean-to’s or roofs; you must conform with all Health and Safety issues as stated earlier in this roofing feature, and also work with an assistant and NOT work in windy conditions.
Fixing clear PVCu corrugated sheets:
Always ensure each sheet is applied vertically running from the highest to the lowest roofing point.
I recommend you follow my overlap recommendations as stated in the bitumenised, corrugated, roofing pitches but would add, if an overlap of clear sheets facilitates a good fit without cutting and necessitates an increase in the overlap, do so with my full recommendations. Do not reduce overlap measurements as it could easily create a gap for water to be blown through in windy conditions.
Drill all your fixing holes to fix clear corrugated PVCu panels (including mini profile panels) through the crown-point and not in the valley. Make all your drilled sheet fixing holes at least 5mm bigger than the screw diameter size to allow for thermal movement as a result of the sun.
Always use a PVC sealing washer on each screw fix as it is designed to stop any rainwater penetration and soften the pressure when the roof sheet is screwed firmly down.
Use a slow speed power drill and sharp drill bit when drilling each hole with a firm support positioned beneath the clear PVCu panel’s corrugated crown. Don’t push the drill; let the drill do all the work and be patient as applying firm pressure can easily split a corrugated sheet at the crown point.
Apply all horizontal wooden purlins across the timber joists at the appropriate 500mm or 600mm centres. Cut a purlin joint recess into each timber joist at the appropriate 500 or 600mm centres to create a flush roof pitch level across the building’s roof. Be sure to take advice from your timber supplier that the cross-member purlins ARE the correct size to support your new corrugated roof.
Laying each clear PVCu sheet:
Ensure all timbers and purlins have been pre-treated with primers, paint or the appropriate wood preservatives recommended by your Builders’ or Timber Merchants. Be sure they are completely dry before starting to apply clear PVCu corrugated roof sheets to your building.
There must be a horizontal purlin in position near the top of the roof pitch and near the extending edge at the bottom, where rainwater will flow into a gutter, or straight off the roof if no gutters are being erected.
When you have decided where these two critical purlins are to be positioned, be sure there are purlins or timber joists located at each corrugated sheet overlap point for fixing the overlapping sheets down firmly with screws.
Place all other horizontal purlins at an equi-distant 500mm or 600mm gap between the highest and lowest horizontal purlin.
Lay your corrugated sheets down loosely at first before starting to make any final screw applications. Adjust the overlaps of any loose fitting sheets to avoid making unnecessary cuts to a fitting size. Both end and side corrugated sheet overhangs must not exceed 70mm and can easily be adjusted at this point before a final fix. Do not attempt to do this work in any windy conditions, or a slight breeze.
Sheet overlaps can easily be lifted and adjusted to hide any excess roof overhang areas, which must not exceed 70mm or a strong wind could lift the roof and cause untold damage to your work.
Fixing points – for drilling – can be clearly marked (by magic marker) on each corrugated sheet’s overlapping and final fix crown-points, together with any cutting lines before the cutting, drilling and final fix is commenced.
Once all markings, cutting and drill holes have been applied, you can then go back on the roof to commence a final fix. Be sure to spread your weight on a roofboard with a soft underside to avoid splitting any sheets.
It is a little like pre-determining the roofing jigsaw pieces before they are finally screwed into place.
Use fine-toothed hacksaws or a fine toothed, electric power saw to cut all your clear PVCu corrugated sheets to size. It might be wise to practice a cut of a PVCu sheet before attempting any final cuts. Always support these big expansive sheets when cutting (through an assistant’s help) before commencing any final cuts. If you are cutting vertically, draw the cutting line on the lower sheet using the upper sheet’s overlapping edge after you have created a new crown overlap line while it is temporarily in position on the roof purlins. You will then create a perfect sized lower cut panel to accommodate a single crown overlap for a final fix of the roofing panels.
To prevent rainwater getting in to a building’s end verges under the clear PVCu roofing sheets, I strongly advocate the sheets must overhang the roof verges by at least one corrugation, but no more than 70mm because of the possibility of damage from high winds.
The maximum size corrugated PVCu roof area for accommodating rainwater flow into gutters using a squareline guttering design, set at 65mm from the roof edge overhang, is 78 to 150 sq. metres. Smaller roof area designs will easily accommodate the rainfall even in a heavy storm
Flat, clear, corrugated PVCu and bitumenised, roofing sheets can be fitted and used in climates not exceeding minus 20 celcius and plus 60 degrees celcius.
They are a great value-for-money, cheaper roofing alternative for the prevailing weather conditions in the UK, Ireland, Scotland and Europe. They are a perfect roofing and canopy sheltering system for covering walkways, car ports, garage roofs, cycle and garden sheds, agricultural equipment barn roofs, livestock enclosures, zoo animal breeding and enclosure shelters, and for creating a cheaper roofing system for covering animal food supplies and materials’ storage enclosures where security is not an issue.
Bitumenised corrugated roofing sheets and clear PVCu roofing sheets offer enormous building savings’ potential for DIY enthusiasts, farmers, zoo owners, builders, landscape gardeners, allotment owners, market gardeners, plant breeders, and business trying to erect new storage areas and reduce building capital costs, wherever possible.
Be sure to think how you can build cheaper, by erecting an economical, corrugated, sheet- roofing system that will dramatically reduce capital outlay costs and yet still deliver on sturdiness, durability and waterproofing.
Cut down the hassle of this sort of job by making the most of the power tools available to you. Power tools often make light work of even the toughest job. Cutting down on the time it takes to complete a job and making your life easier.