Welding Pitched Roofs

A construction worker in a red safety helmet installs waterproof roofing membrane on a steeply sloped roof, using a welding machine against a scenic mountain backdrop.

The pitched roof is definitely the most preferred roof type in privately owned homes. This is true not only for cultural or visual reasons. The construction and maintenance costs are lower for pitched roofs. The facade is protected by pitched roofs, and rainwater can drain effectively due to the incline.

The subroofing membrane as a part of the roof structure, which is laid under the actual roof covering, i.e. under the roof tiles, is a second water-draining layer that protects against drift water, capillary, backwater and condensation water as well as against dirt. If a roof membrane film is used as a subroofing membrane, it can be welded with Leister automatic welding machines.

New regulations in some European countries require homogeneous welding of roofing underlayments. Adhesive tape joints are no longer permitted. Under-roof membranes are required for additional protection under the sloping roof shingles. Both types of welding - from bottom to top and from top to bottom - are easily possible with Leister welding machines. Thanks to the optimized wedge geometry, even thin membranes (0.3 - 1.0 mm) can be welded perfectly.

For plumbing work on the roof, Leister offers special nozzles that make work easier for roofers and plumbers. Rain gutters and other metal parts made of copper, zinc and chromium steel can be soldered flamelessly and in an environmentally friendly way with the TRIAC AT and the corresponding soldering iron kit.

For further information, please refer to the expert topic “soldering”.

Properly weld the roofing underlayments

Only a few correctly executed steps are required to make the welded roofing underlayment meet performance standards.

A construction worker in safety gear uses a specialized welding machine to install waterproof membrane sheets on a sloped roof at a scenic, outdoor building site.

With the right membrane material and the use of high-quality welding machines and manual welding devices, every category of sub-roof can be welded perfectly, no matter whether normal, increased or extraordinary stress is expected on the roof.

SIA Standard 232

New regulations have applied for roofing underlayments since the introduction of the SIA Standard 232 in 2000. Sub-roofs are subdivided into three different categories:

normal stress for customary water drain-off
increased stress - waterproof against water accumulation of max. 50 mm
extraordinary stress - just as with increased stress with additional backwater protection

Changes to the SIA Standard 232/1:2011

The revision of the SIA Standard 232/1:2011 makes a uniform provision and classification of the roofing category possible and thus has an influence on the selection of material and design of a sub-roof.

Starting at a reference altitude of 800 m above sea level, a sub-roof is required for extraordinary stress.
Independent of the reference altitude, in thermally insulated roofs with a roof pitch of less than 15°, a sub-roof is required for extraordinary stresses.

Requirements of sub-roof materials for extraordinary stresses:

Sub-roof systems and materials must withstand the expected high pressure (water level 50 mm).
Homogeneous welding of overlaps and connections, and special sealing of penetrated spots must be ensured.

(Source: Gyso)