WORKS WITH FLAT HOT-DIP ZINC COATED AND COIL COATED STEEL SHEETS
This technical specification refers to roofing, manufacture and installation of horizontal and vertical gutters, flashings, windowsills, expansion joint covers etc.
1. Relevant standards
EN 10346 (2015) Continuously hot-dip coated steel flat products - Technical delivery conditions
EN 10142 (2000) Specification for continuously hot-dip zinc coated low carbon steel sheet and strip for cold forming: Technical delivery conditions
EN 10327 (2004) Continuously hot-dip coated strip and sheet of low carbon steels for cold forming - Technical delivery conditions
EN 10130 (2006) Cold rolled low carbon steel flat products for cold forming - Technical delivery conditions
EN 10169 (2010) + A1 (2012) Continuously organic coated (coil coated) steel flat products - Technical delivery conditions
EN 10169-1 (2003) Continuously organic coated (coil coated) steel flat products - Part 1: General information (definitions, materials, tolerances, test methods)
EN 10169-2 (2006) Continuously organic coated (coil coated) steel flat products - Part 2: Products for building exterior applications
EN 10204 (2004) Metallic products - Types of inspection documents
and other standards mentioned in these standards.
Class DX51D according to EN 10142 for cold-rolled hot-dip galvanized sheet metal is acceptable, zinc coating should be not less than 275 g/m2. The edges should also be coated with zinc.
There are no special requirements for surface quality (A or B).
The thickness of the sheet should be at least 0.55mm.
For works performed with continuously organic coated (coil coated) sheet metal - the thickness of the top layer (face) should be at least 35µ (priming coat and topcoat), UV resistance according to EN 10169-2 at least class RUV3 and corrosion resistance according to EN 10169-2 at least class RC3.
The contractor is obliged to submit manufacturer's certificates for all materials to the supervisor for approval, through the submittal process, before procuring the material. Data on the content of volatile organic compounds (VOC) should be provided.
The manufacturer's warranty should be at least 15 years.
The sheet metal delivered to the construction site must not be damaged and should be stored in a dry and ventilated place. Stored sheet metal coils must not touch each other.
Prior to the commencement of works, the contractor is obliged to submit to the supervisor shop drawings and the method statement, which must include a quality control plan.
All dimensions should be checked on the construction site before the production of elements. At the request of the supervisor, the contractor is obliged to make a sample (mock-up) to obtain approval for further production.
Particular attention should be paid to the fact that the elements located in the exterior are designed so that no water is retained on them.
Before starting work on covering the sloping roof with flat sheet metal, the wooden base should be inspected. The surface should be flat and made of dry boards without defects.
Bituminous underlayer for discontinuous roofing to be placed on a wooden base (boards 24 mm thick with a spacing of 0.5-1.0 cm). The underlayer should be attached to the board base mechanically, with an overlap of 10 cm. In winter, before installing the underlayer is to be left in a room with a temperature of not less than + 10ºC for at least 24 hours before installation.
Sheet metal strips should be joined together with a double lock standing seams (in the direction of the roof slope) and double flat lock seams (parallel to the eave) with a seamer machine or manually. Fixing elements to be made of the same material as the sheet metal.
Joints of two elements of hot-dip zinc coated horizontal gutters should be riveted (at a distance of 3cm) and soldered with tin. Gutter holders should be made of hot-dip zinc coated tape 25x5mm at a distance of 80cm. The gutter and holders to be fixed with Ø4mm rivets. The minimum overlap at the joints is 25mm (the direction of water flow should be taken into account). Flashing above the gutter should be joined with the gutter with a double seam and tinned.
The vertical hot-dip zinc coated gutter pipes should enter each other at least 50 mm and be tinned. Hot-dip zinc coated pipe brackets with holders to be placed at a distance of no more than 2m. A decorative collars should be placed over the brackets. The pipes must be at a distance of at least 20 mm from the wall finish.
Joints of horizontal gutters made of coil coated sheet metal should be riveted also but sealed with silicone. Brackets and holders should be made of coil coated material.
Attic wall flashing and exterior sill should be done according to the details in the design. The edge of the window sill at the joint with the window to be at least 25 mm higher than the outer edge. The gap between the outer edge of the window sill and the facade wall should be at least 3 cm. Bituminous underlayer to be placed over the base of concrete or mortar, below the sheet metal.
During the execution of works, care should be taken that different metals do not touch each other.
For the performance of works at a temperature lower than + 5ºC, the consent of the supervisor should be obtained.
It is not allowed to cut the sheet metal with a grinder, sheet metal scissors or a jig saw should be used. After cutting, the edges to be protected from corrosion. Immediately after installation, the sheet metal should be cleaned of sawdust and other metal parts.
Minor damage to the sheet metal surface, which occurred during the execution of works to be repaired according to the instructions of the material manufacturer with the consent of the supervisor.
4. Supervision and measurement of works
The supervisor should check that the material specified in the design is installed and that the material is not damaged during the execution of the works. In particular, it should be checked whether all joints are made according to details provided in design, seams are done neatly and the joints of gutter pipes are tinned or sealed. For all hidden works there should be a checklist of the performed control, signed by the responsible person of the contractor and the supervisor.
Unless otherwise defined by the contract, roof covering is calculated per m2 of covered area, installation of gutters and flashing per m’ and rainheads, overflow pipes etc. per piece.
Please note that the technical specifications on this web site are templates only, information provided should be carefully checked and aligned with your project needs.
The steel grades are classified in accordance with their increasing suitability for cold forming as follows:
DX51D: bending and profiling quality;
DX52D: drawing quality;
DX53D: deep drawing quality;
DX54D: special deep drawing quality;
DX55D: special deep drawing quality (only +AS);
DX56D: extra deep drawing quality;
DX57D: super deep drawing quality.
The mechanical properties can also be marked as follows:
DC01 - This grade can be used for simple forming work, for example bending, embossing, beading and pulling are used.
DC03 - This grade is suitable for forming requirements such as deep drawing and difficult profiles suitable.
DC04 - This quality is suitable for high deformation requirements.
DC05 - This thermoforming grade is suitable for higher forming requirements.
DC06 - This special deep drawing quality is suitable for the highest deformation requirements.
DC07 - This super deep drawing quality is suitable for extreme deformation requirements.
Surface type A
Mistakes such as pores, small grooves, small warts, slight scratches and a slight discoloration that does not affect the ability to reshape and adhere to surface coatings are permitted.
Surface type B
The better side must be free from defects so that the homogeneous appearance of a quality finish or an electrolytically applied coating is not impaired. The other side must at least meet the requirements of surface type A.
Z275 is the normal coating class, Z200, Z450 and Z600 are optional.
Metal sheets of some renowned manufacturers have a thickness of the covering layer even 55μ, but there are also sheets with a thickness of the covering layer below 25μ.
Resistance to UV radiation is classified from RUV1 to RUV4, where RUV4 means the highest resistance. Corrosion resistance is classified as RC1 to RC5, where RC5 is the highest resistance. Sheets that meet the requirements of RUV4 and RC5 are expensive and are used mainly in aggressive environments, by the sea and for representative facilities where the highest quality is required.