How To Install Underlayment For Roofing

Andrew is a professional carpenter who has over 15 years of experience.

The modern-day metal roofs, which have been manufactured by following the highest quality standards, aren't worse than any other roof material. It's also extremely easy and fast to install as the material comes as up to 10 m2 plates. I'm sure that most construction workers also like the fact that it doesn't require a full wood purlin.

So if your house needs a new roof, then metal is the way to go. They come in different colors and finish types. Not to mention a whole selection of different profile types. There's something for everyone.

The edges of the metal roof panels can be quite sharp. They can easily cut through an electrical power cord, and that can create some dangerous situations. That's why it's better to always use a cordless drill when installing a metal roof. Go with anything that's high quality. Some of the most professional brands are Bosch, Makita, and Metabo. So try to avoid cables as much as possible when working with sharp metal sheets.

Hammer / Nail gun
Crowbar
Measuring tape
Pencil
Circular saw
Hand saw
Screwdriver bits / Cordless screwdriver
Cordless drill
Stapler
Sheet metal cutters

Tips for Easier Installation

The edges and corners of the metal sheets are sharp. That's why you should always use work gloves to avoid injuries.
Avoid bending the sheets while moving them. It can really ruin the final look.
Store the metal sheets on a flat surface. It would also be great if you could store them in a small angle so that water can runoff.
Do not cut the metal sheets with a circular saw. It can ruin the galvanization and make it corrode. That lowers the lifetime of the roof as the corrosion can spread throughout the metal sheet.
Avoid scratching the metal sheets as it can make it corrode.
Only use screws with seals for installing the metal panels.
Metal sheets that have received scratches or any damages on the surface, should be repainted.
Sealed screws make it more resistant to storms.

Removing an Old Roof and Installing on the Purlin

If your old roof is made out of eternit, then the first thing you should pay attention to is the fact that eternit includes asbestos, which is dangerous to breathe in. That's why you should always use a respirator when removing them.

Since adding a new roof is a long-term investment, then I also recommend inspecting the old roof purlins and rafters while you are at it. Sometimes it's worth rebuilding if it's in a really bad shape.

A metal roof requires using a base sheet. Its main function is to protect the wooden purlins from water. Metal roof panels are connected with overlapping joints, so there's always a way for water to get under. The base sheet protects you from that.

That's why it's recommended to choose a plastic or bitumen base sheet. They don't absorb any water. However, I do recommend choosing a type that has one side that can absorb condensate.

The base sheet can be installed both horizontally and vertically. Vertical placement means that the distance between rafters needs to be 30 cm shorter than the width of the base sheet. With vertical placement, you are supposed to measure the length of the sheet in a way that it sits over the sides. With horizontal placement, you should also cut lengths that sit over the side walls. You should also have enough length that you don't need to tighten the sheets later. All of the base sheets can be cut on the ground and then lifted up. The installation should start from the sidewall and then move towards the other side.

The base sheets are fixed to the rafters with large-headed nails or staples. The sheet should be loose enough between the rafters that it makes a small groove that directs water away from the roof.

Then you install the next sheet panel and overlap the first one by around 20 cm. Again fix it to the rafters and keep doing it with the rest of the panels.

Next, install a purlin on top of the base sheet and rafters. These really fix the base sheet and later on work as a base for the metal roof.

Purlins

A purlin distributes the weight evenly to the rafters. In addition, it creates a path for the wind and air to move through. This is a must as it makes sure that the entire construction is dry and you don't need to worry about condensate. Also, the roof metal panels are installed to the purlin.

Different metal roof profiles have different requirements of the perlin. Some require less of them, and some require more. All of this is written by the manufacturer, and you should definitely follow what they recommend.

Installing the Roof Panels

You first need to lift the metal panels onto the roof. Be careful not to bend or damage them. It might be a good idea to build a strong wooden ramp that you can use to slide them up.

The first plate should be placed onto the roof so that it stays over the edge by 30 mm. You should also attach it from the center with one screw so that you can, later on, adjust the position if needed.

The second plate is positioned right next to the first plate and also attached with one screw. Adjust both of the plates so that they align and overlap. Once you are happy with the result, attach them both to the rafters with special sealed screws.

Carry on doing this to all of the roof plates.

Correct Maintenance Is the Key for Longevity

It takes quite a bit of work to fully install a metal roof. And it doesn't mean that the work is over after you are done. A metal roof still requires yearly maintenance to keep increasing its lifespan. The roof should be cleaned from dirt at least once a year. Preferably twice, once in the autumn and once in the spring. You can wash the roof with a soft broom and water.

The snow will slide right off in the winter, so you don't need to usually push it off. However, this mostly depends on the angle. If it starts collecting a lot of snow, then you should definitely remove it to avoid any possible dents from increased weight. In which case you should also use something soft and blunt to remove the snow. Sharp objects can damage the surface, and you risk corrosion.

This article is accurate and true to the best of the author's knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Muhammad Waqas from Pakistan Punjab City sheikhupura on November 02, 2018:

This is the matter of quality it's about art ,

It's depend on yourself whatever you want when you going to start anything