Metal roof tiles or trapezoidal steel sheets: what to compare before buying

Tile-effect metal roofing has transverse steps and waves imitating the layout of roof tiles. It creates a distinct rhythm that combines well with a house of traditional form. Trapezoidal sheet runs in straight lines from eaves to ridge. Its appearance is calmer, although a high profile can stand out strongly on a small roof.

It need not be assigned exclusively to a hall or garage. On a house it can look good if it suits the proportions of the roof, eaves and façade. Assess a larger sample in daylight. A small colour swatch will not show the shadows between the profiles or the sheen of the whole roof slope.

The covering is selected for the actual roof pitch. Profiles with a similar name may have different conditions of use. This also applies to T18 and T35. The minimum pitch of one product must not be transferred to the whole family. The shape of the overlap, the length of the drainage path and the connections of the sheets are significant.

A roof with a single sheet along the length of the roof slope behaves differently from a covering with a transverse overlap. The documentation may impose stricter requirements on the latter. If the roof is close to the permissible pitch limit, the sealing details must be established before ordering, not during installation.

With a similar thickness and grade of steel, a higher profile may provide greater rigidity. This does not mean, however, that T35 always allows an arbitrarily wide support spacing. The tables for the specific product and the loads assumed for the building are needed. Snow and wind suction do not depend on the price of the sheet.

Tile-effect metal roofing requires battens matched to the rhythm of the profiling. Trapezoidal sheet also needs proper support, but the spacing is determined according to different rules. During renovation, the existing roof structure and battens must be checked. The low weight of both coverings is not confirmation of the good condition of an old structure.

On simple roof slopes, long trapezoidal sheets or cut tile-effect sheets may reduce the number of joints. Lengths are selected according to the roof measurement and the flashings envisaged. Ordering sheets with excessive allowance increases waste, and sheets that are too short cannot be remedied by a wide strip of sheet at the eaves.

With dormers, roof valleys and hips, it is worth comparing the exact cutting layout. Modular tile-effect metal roofing makes it easier to carry and handle small elements. It does not, however, eliminate offcuts. A cut-off piece cannot always be used on the other side of the roof because of the direction of the overlaps and the shape of the profile.

First check the unit. A square metre of total sheet does not correspond to a square metre of surface covered after the overlaps are made. For modular products, the price of a sheet must be converted by its effective area. Two offers must also cover the same thickness, coating and method of taxation.

Add screws, flashings, ridge tiles, layers beneath the covering, transport and labour to the comparison. A roof valley or chimney flashing does not disappear just because a cheaper profile was chosen. It is best to compare full cost estimates for the same geometry, instead of multiplying the roof area by an advertising rate.

The sound of rain cannot be reliably assessed from the name of the profile alone. The whole assembly matters, including insulation, the attic lining, the method of fixing and airtightness. Exposed sheet metal over a carport will behave differently from the same material over a correctly constructed attic.

The same applies to temperature. Thin sheet metal does not replace thermal insulation. If a heated room is to be created beneath the roof, insulation, vapour control and ventilation must be planned. Solutions for an open carport should not be transferred unchanged to a bedroom in the attic.

Trapezoidal sheet works well when it matches the design and its straight line and method of installation suit the project. Tile-effect metal roofing makes sense when you want the rhythm of roof tiles and have the conditions to lay the chosen profile. Both materials require a coating suited to the surroundings, as well as correct details.

With a complex roof, it usually pays to devote more time to the cutting layout. With a long, simple roof slope, transport and the safe delivery of the sheet may play a greater role. The best decision results from these specific constraints, not from a general conviction that one group of sheets is always better.

Ask for two schedules for the same roof plan. Each should state the effective area, the number of sheets, the flashings and the delivery cost. This will show you whether the difference in the price of the profile remains a difference in the price of the whole order.

The choice between trapezoidal sheet and tile-effect metal roofing begins with the geometry of the roof and the requirements of the structure. Only then compare appearance and cost. A well-chosen material does not require circumventing the instructions on pitch, overlaps or fixing.