Corrugated plastic roofing

Corrugated plastic roofing

Corrugated plastic roofing is not intended to be a main house roofing system, but rather it is very useful for smaller roofs around the home.

Many of these products are manufactured to share the same profile as similar steel rolled formed sheets. It does not mean however that they are as strong and caution should be used when walking on roofs with these products as I have seen some that are extremely fragile looking when new and downright dangerous when aged and affected by sunlight.

That being said there are a lot of very strong and good looking products that are excellent for their purpose.

  • There are a series of very strong commercial grade fiberglass sheets that are made specifically for very corrosive environments. The factory that I go to that does hot dip galvanising has had it’s steel roof replaced at least twice to my knowledge. Why they don’t replace the sheeting over the caustic or acid cleaning baths with fiberglass I don’t know.
  • Apart from strength there are also many different colours and transparency ratios. From clear though grades of translucency to opaque. Some of them that filter UV but still let plenty of light through.
  • A few times I have done an addition to an existing house that consists of a roofed patio or verandah. I live in the tropics, so we do many of these for outside living areas and shade, so we use steel sheeting. When the new roof is completed it sometimes shades the kitchen window, so we put a couple of sheets of corrugated plastic roofing that is the same profile as the steel roofing to allow natural daylight to get into the kitchen again.
  • After doing a couple of these I have come to the conclusion that a single sheet of clear or semi opaque sheeting would make an excellent substitute for a skylight. It may not look as good as a skylight, but it could possibly be only a tenth of the cost.
  • Some manufactures standardise on smaller sheets say 1800 (6ft) long and actually call them corrugated plastic roofing tiles. Others make sheets up to 3000 (10ft) long.
  • In temperate climates these translucent sheets can provide soft filtered light for decks and sun rooms.
  • Many of these products are excellent for greenhouses and they are a cheap alternative to glass.
  • All of these corrugated plastic roofing products have a large thermal expansion rate, compared to most other roofing materials. FRP (fiberglass reinforced panels) at a lesser rate than Polycarbonate and PVC panels.

Fixing tips

  • Some of these corrugated plastic roofing panels will not hold your weight if you stand between supports, you must read the manufacturer’s instructions in regard to correct fixing.
  • Wear safety glasses when using power tools. The small chips really fly on some of these brittle materials.
  • A barrier cream can stop the itch effect when cutting fibreglass corrugated sheeting.
  • Because of their large thermal expansion rates these products should have their fixing holes pre-drilled at least 2mm larger than the fixing screws.
  • Polycarbonate sheets have a UV resistant layer on one side of the sheeting. This layer faces the sun and each sheet is marked which way to fix.
  • Follow the manufacturer’s recommendation’s for fixing screws, washers and seals.
  • Don’t over tighten. Set the screw gun so that you can slowly wriggle them in, stopping as soon as the seal grips the sheet.
  • Don’t store a stack of translucent sheets in direct sunlight. They can build up a terrific amount of heat and this can cause a clouding effect in the sheet which can not be removed.
  • Some of the thinner sheets can be cut with a sharp hand saw, and I have also used tin snips for small cutouts. These thinner sheets can also be cut lengthwise with a utility knife.
  • Thicker sheets need to be cut with a power saw. Use the finest toothed blade that you can find. Using a coarse blade can cause splinters to fly and leave a very rough edge.
  • A normal HSS drill bit will drill the sheets easily if it is kept sharp.
  • As a general rule try not to drill too close to the ends. I like to arrange the purlins so that end holes are about 100 (4") from the end.
  • Corrugated plastic roofing
  • Another general rule is to keep the purlins a lot closer together. Like 600 or even at 450 centres, but take the manufacturer’s advice on this for your area.

When travelling in the outskirts of an urban city you would see many roof tops in plastic and fiberglass materials which have wavy pattern in them. These roofing materials are known as corrugated roofing. The reason why this design of roofing is very popular in both urban and rural homes is because they are very sturdy due to the presence of alternate grooves and ridges. Many materials are used to make this type of roofing’s but below we have tried to understand the basic features of Corrugated Plastic Roofing and the basic things to keep in mind during the installation process.

What are the basic features of corrugated roofing when made from plastic?

1.    Corrugated plastic roofing is manufactured from polycarbonate plastic.

2.    Now days they come in a variety of textures which could be translucent or clear too.

3.    They also come in various vibrant colors which can be used with your existing home décor.

4.    The grooves and ridge patterns of these corrugated roofing when made from plastic makes them durable in any climatic conditions.

5.    They can also be used in extreme monsoon climates as excess water is removed with the presence of these ridges and grooves.

6.    These plastic corrugated roofing’s are used to cover green house in your garden, outside patio area of your home and also airport outside areas.

7.    The use of plastic corrugated roofing’s makes them expensive.

8.    They are easy to install.

9.    They can be painted fresh after some year and this makes them economical.

10.    Before using these plastic roofing’s take the advice of an expert to implement whatever water proofing measures you would require before installing them.

Basic Guidelines to understand during the installation process

•    You would need to mark the Corrugated Plastic Roofing material using a water proof marker and then cutting it with the table saw as per specifications. When cutting the material you can use clamps at the side and this would make your work easier. Also do not forget to wear protective gear like goggles and gloves when undertaking the task.

•    For fastening the molding trips to the roofing panels you would need a nail gun. The nail gun would attach the rafters and cross braces to the molding trips. Here you might need to drill holes and it is best to start from the highest point of the roof to the lowest point. The drilled holes can enjoy a size of around 2mm in diameter. You can also use sealants to make your work more secure.

•    If you are installing the plastic corrugated roofing from one side to another you have to take care that each panels overlaps the other properly. You can use a sealant which is made of silicone to prevent water from running inside.

•    If you are installing the plastic corrugated roofing from the top to the bottom areas of the roof then you would start from the bottom and then work your way to the top area.

What are the benefits of using these plastic corrugated roofing?

Add color to the existing home décor

Plastic corrugated roofing come in a variety of colors and when you add these colors on your roof your outside home décor would receive a face lift and your home look good as new. You can also do away with traditional boring colors like grey, brown and red.

Introduce sunshine in your room

Other types of roofing materials completely block the sunshine from entering the room. When you use these plastic corrugated roofing in your outside patio area or green room you can enjoy the natural sunshine and cut out the extra electricity expenses.

Say goodbye to water pooling

During the monsoon season most homeowners face the problem of unwanted water pooling in their roofs. When you use these plastic corrugated roofing you would have free flow of water from the roof to the side gutters in your home in no time.

Easy maintenance cost

When you use old traditional roofs you have to have specialized people to clean them at least twice a year. When you use plastic corrugated roofing you and a group of friends can clean them at regular intervals after observing the safety measures.

Roofing materials are available in different types. A corrugated roofing refers to the large panels of roofing material that come in a wavy pattern. It is the alternate ridges and grooves that make them stronger. This can be explained with the example of corrugated cardboard, in which overlapping sheets of papers are reinforced with the ridges and grooves. Various materials are used for making corrugated roofing, and they include steel, fiberglass, plastic, etc. Corrugated plastic roofing has the typical ridges and grooves pattern, and is made of polycarbonate plastic.


This type of roofing comes in different colors that range from clear and translucent, to green and blue. The ridges and grooves pattern makes them strong, and allows water run off. While the wavy pattern is known as round profile corrugated plastic roofing sheets, even box profile types with box-type ridges are available in the market. Usually, these roofing panels are used for covering patios, carports, and greenhouses. Clear sheets are used for covering greenhouses, as this material admits enough light into the structure, and maintains the temperature and humidity levels. Sometimes, these roofing panels are also used as siding. Some types are reinforced with fiberglass threads.

This roofing material is lightweight and is easy to install. As compared to some other types, like the corrugated fiberglass roofing, these plastic panels are inexpensive. However, they can be weaker than other types, like the corrugated sheet metal roofing. So, avoid walking over these plastic panels. Even accumulation of snow and other debris must be removed regularly. However, they are resistant to corrosion and weather damages. They can also be painted afresh, if the color fades off. Before installation, you have to make sure that the roof is having a pitch of at least one inch per foot, so that the water will drain properly. Otherwise you have to opt for some additional waterproofing measures.

Installation Tips

Cutting. If you want to cut corrugated plastic roofing, use a fine-toothed hand-held power saw or a table saw. Measure and mark the sheet, as per the required dimensions. Use table clamps to attach the edges of the roofing panel to the surface of a table, so that the part of the panel you want to cut hangs off the table. Put on the safety goggles and gloves, before cutting the roofing panel through the markings. It will be always better to use the blade with the smallest tooth, for this purpose.

Fastening. You have to use round molding strips on vertical rafters and corrugated molding strips on cross braces. Use a nail gun and attach the molding strips to the rafters and cross braces, using aluminum nails. In order to nail the roofing panel to the wall, you have to drill holes, beforehand. It is often recommended to drill holes on every fourth corrugation, that too, at the higher points. The holes must have a diameter of eight to ten millimeters. The diameter of the holes must be wider (around 2 mm) than the diameter of the fasteners, because the sheet may expand slightly, during hot weather. There are various types of fasteners with water sealants, and it is better to opt for such versions, rather than the regular ones.

Sealing. There are certain basic factors that have to be taken care of, in case of corrugated plastic roofing installation. If you go for side by side installation, make sure that the panels overlap properly. You should also caulk the seems with a silicone sealant, throughout its length, so as to prevent water from entering inside. It is always advisable to overlap the ends of the adjacent sheets, by one corrugation. If you are installing them one above another, then, it will be better to work from bottom to top.

In short, corrugated plastic roofing can be a perfect choice for greenhouses, patios, carports, and other such constructions. You must understand its pros and cons, before investing on this product. If you find it not suitable for your purpose; go for other types, like metal roofing or fiberglass roofing.

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