E-MAGAZНN     Everything You Need to Know About Lightweight Roof Tiles

E-MAGAZНN     Everything You Need to Know About Lightweight Roof Tiles



The extreme impact of weather is occurring more and more! Is this just imagination or fact? At any rate, uncommon and extraordinary conditions do happen from time to time, which can either destroy property for some, and may "only" cause hours or days of fear for those with cottages, homes or places of business, whether this time the structure will survive …… We are speaking of windstorms, hailstorms or snow avalanches. The winter of 2006 and the snow calamity in Central Europe under which roofs caved in, hurricanes and windstorms in Germany and France, and also in the Czech Republic and Slovakia during past several years which tore roofs to pieces, the hailstorms in Slovenia and the Czech Republic and many other countries not only in 2008; these all depict the strength of natural elements. After years of experience, the methods of slanted roofs and the choice of traditional materials often received a very rude awakening. It is likely that we shall be experiencing more of such events, and thus it is good to know what can happen, and what solutions are available. During the past decade, significant changes have also occurred in the utilization of attic (under-the-roof) spaces, and so damage to a roof often means a direct hit and large material damage even inside the structures.

Problem No.1: — volume of snow on a roof and the burden on the roof and entire structure which results from this. In terms of roof covering, this not only regards surface bearing-capacity, but also its resistance to freezing and temperature change (day-night or sun-shade), which has the consequence of the melting and freezing of ice and its buildup in critical areas of the roof, especially in the neck gutters and above eaves. On a significant level, this relates to whether the covering allows for resolving parts in such a manner that it secures their firmness and tightness, and during the accumulation of more influences. The overall bearing capacity or small bearing capacity of the structure is another matter.

In the mountains, most roofs, or structures in general, are designed for light roof covering or are in a state which calls for the least amount of burden. Light roof coverings differentiate in their materials, appearance, price, firmness, as well as resistance and durability. Not all types of light roof coverings are suitable for climatically-exposed situations and locations. From the view of stress due to snow, sheet-metal coverings are the most suitable, mainly folded systems or small-format steel tiles. Large-format sheet-metal coverings are suitable only for roofs with a simple shape without neck gutters, roof windows or skylights, etc.

Sheet-metal roof tiles — small-format.

1. Tiles with stone granulate on surface.

Advantages: This is a small-format covering which is added in templates on one line of strips and has a length of ca 1.25m (ca 0.5m2). Edges of the tiles in the neck gutters and other parts are modified above the sheeting by bending in such a way that the space given due to the transverse profile of the tile is completely closed, and no ice can get underneath it, which could damage it. In a similar fashion, underneath the leeward plinths or on the corners of hipped roofs, the tiles are modified in such a way that leakage is impossible during the blowing of snow or water. Additionally, the small-format also allows for working with minimal cutting even on indented roofs. The method of mounting with rust-free nails from underneath over the frontal edge of the tile to the board does not disturb the upper surface of the roofing, and the heads of the nails are not affected by sliding snow or ice. The mounting remains firm even during extreme strain and wind gusts. There are 6-7 nails used per m2. The granulate deadens noise during rain and gives exceptional resistance to the surface and protects from the sliding of snow and ice into critical parts and allows for its gradual thawing. The surface bearing capacity of the tiles is 600-1200kg/m2 according to type, so the limiting factor for selecting this type of surface is only the bearing capacity of the truss.

In mountain areas, it is recommended to add snow-catching devices to problem areas and coverings with granulate.

2. Smooth-surface tiles — small-format.

Advantages: The construction advantages are the same as for the tiles with granulate, but the difference is that smooth surface allows for easier sliding of snow from the roof. It is therefore necessary to protect the windows, chimneys, eaves, etc. on roofs from snow drifts or ice damage, or even persons and structures underneath the roof and in the surroundings of the structure. Snow-catchers above the critical parts or over the entire surface of the roof are used for this.

Large-format shaped sheet-metal coverings.

Advantages: Easy snow runoff thanks to smooth surface.

The problem is the open transverse profile (from the side) in the neck gutter and around all sheeting, which has the consequence of pushing and freezing ice under the edge of the roofing mainly in the lower part of the neck gutter, and subsequently, the pulling-out and deformation of the parts caused by moving ice. Because snow does not stick to a smooth surface and slides down, this leads to the pilling of the snow in critical parts. This can only be prevented through the use of surface-wide snow catchers. The slabs are screwed from above at the bottom of the profile, and it is thus apparent that the sealing around the screws comes under stress both mechanically — when ice falls off, during the heat expansion and retraction of the slab, or during wind suction, and also chemically- acid rain and UV rays. The surface modifications generally have a worse quality and mechanical resistance when compared to the technologies for surface modifications of small-format sheet-metal tiles.

Damage to roof covering from falling snow from neighboring roof

Folding sheet-metal systems

Advantages: Traditional roofing solutions in the areas of high snow cover. Certified and reliable solutions to critical parts in view of the effect of ice and snow. Material alternatives — steel, aluminum, copper, titanium-zinc and many other variations of smooth surface modifications.

Problems sometimes arise in view of resistance to windstorms. As soon as the wind tears off a small part of the foundation, the entire roof subsequently opens like a can of sardines. Another common mistake is the absence of ventilation in the roof casing.

E-MAGAZНN     Everything You Need to Know About Lightweight Roof Tiles

Asphalt shingles

Advantages: If quality shingles are selected, then the advantage is the good workability of covering of the crimps, shoulders and shallow neck gutters (if the neck gutter is not sheeted, but is made up of shingles on the foundation from a fused asphalt belt). If the shingle is placed on a quality foundation, and the individual templates are mutually well-glued, then the roof casing even becomes well-resistant to moving snow.

The most common problems arise in relation to the selection of cheap shingles. The production technology of these shingles most likely does not take into consideration their use in colder climate areas, as well as the quality of the foundation and the assembly itself. The influence of these factors causes the shingles to rise, and subsequently rip off. Another problem is the securing of tightness between the shingles and sheeting in certain parts.

Cement-fibrous templates

This type of material presents no advantages in view of snow burden. Problems occur with the cracking of individual shingles on the surface, and mainly in the neck gutters and other parts where the shingles are often ripped from their grip to the foundation. Of course, with regard to this material much also depends upon its precise assembly.

Plastic covering

A) Type — flat templates.

The material itself is basically indifferent to freezing and surface burdens. The resistance of plastic is given mainly by the sturdiness of fastening of individual templates. As a replacement for expensive slate or fragile cement-fibrous templates in demanding conditions, this covering may play a significant role.

Most commonly a large-format covering with edges that remain open in neck-gutters and other parts. From this arise problems with freezing of ice under the covering and subsequent defects. The surface bearing capacity of slabs differentiates between profiles and types used. These materials find more use in countries with warmer climates.

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