Roof renovation buyer’s guide
A successful roof renovation is based on a carefully prepared contract and high-quality materials. Choose a reliable provider that is familiar with building regulations and uses roofing sheets and roofing screws with a 20-year manufacturer’s warranty.
How to ensure a long-lasting sheet metal roof
Almost all roofing sheets installed in Finland have a three-layer coating. Their weather resistance and suitability have been verified through testing, and they come with a 20-year rust protection guarantee.
A three-layer-coated roofing screw is now available on the market. Thanks to the Durabl3 three-layer coating developed by Kingi and internationally patented, the corrosion resistance of the KINGI® roofing screw has been tested to be at least as good as that of a three-layer-coated roofing sheet.
1. Require compliant roof installation
According to building regulations*, compliant installation of a metal roof requires that roofing screws have the same corrosion resistance as the roofing sheets. Unfortunately, high-quality sheets are often installed with single-layer painted roofing screws suitable for indoor use, which do not comply with the regulations. Roofing screws that rust and leak cause an unnecessary and costly replacement of the screws.
Pay attention to the roofing screws
Make sure that your corrosion-resistant roofing sheet is fastened with an equally corrosion-resistant roofing screw.
Make sure that the roofing screw meets ALL of these requirements:
- A three-layer-coated roofing screw for three-layer-coated roofing sheets
- The roofing screw has the same warranty period as the roofing sheet, in writing and including the warranty terms
- The roofing screw is officially approved in Europe for the C4 atmospheric corrosivity category (ETA-25-0267)
- The durability of the roofing screw installed in the roofing sheet for outdoor use has been tested with stress tests
Require the following text in the contract: KINGI® roofing screws shall be used for fastening roofing sheets and flashings.
* The basic idea of building regulations is that products in the same application have the same service lives: they last equally long with the same maintenance. In addition, the technical requirements concerning steel structures stipulate: “The corrosion resistance of connectors, fasteners and sealing washers shall correspond to that of the assemblies to be fastened”, SFS-EN 1090-2, section 5.6.1.
2. Identify a lawful attachment
Warranty
A responsible professional provides a written warranty corresponding to that of the roofing sheet and acceptable warranty terms for roofing screws as well. KINGI® is the only roofing screw for which the manufacturer provides a 20-year rust-through warranty, a 30-year leak-proof warranty and a 50-year cross-section rust-through warranty. The roofing screw also plays an important role in the warranty of the roofing sheet. A poor-quality roofing screw can easily scratch the roofing sheet, in which case the warranty of the scratched roofing sheet usually becomes void.
Crown
Anyone can determine the longevity of a sheet metal roof fastening from the screw head. The head of the KINGI® roofing screw resembles a crown. The crown-like shape of the head has been designed for its intended purpose and is protected by a design registration exclusively for Kingi’s use. Water drains away from the screw head through the gaps between the points and does not remain there to cause rust. The high-reaching points also strengthen the grip of the installation socket, ensuring fast and precise installation without scratching the roofing sheet.
3. Don’t be fooled
The price of a three-layer-coated KINGI® roofing screw is slightly higher than that of single-layer-painted roofing screws that are suitable only for indoor use. In the total price of a roof renovation, however, the price difference between roofing screws is negligible, less than one per cent. It is a small share of the total cost of the roof and a small price to pay for making the roof compliant with regulations and long-lasting.
So don’t be fooled, a negligible “saving” can have really expensive consequences due to the premature replacement of roofing screws and possible leaks.
Fastening durability has been tested
HAMK tested the roofing screws sold in Finland. A 1,000-hour stress test was used to test the long-term durability of roofing screws installed on roofing sheet metal. Based on the corrosion behaviour of the sheet metal’s Pural three-layer coating, 1,000 hours corresponded to more than 20 years of use in the Finnish climate.
On the left, a single-layer-coated roofing screw at the 618-hour mark; on the right, a three-layer-coated KINGI® roofing screw that withstood the 1,000-hour test flawlessly, after the test.
A sustainable choice is easy in every way
The long-lasting building products you have chosen ensure that your property retains its value. KINGI® roofing screw is a patented Finnish innovation and the only roofing screw manufactured in Finland. It is a Key Flag product, and by choosing it you also create jobs and well-being in Finland.