Calculate and check
In contrast to painting a wall, when assessing the amount of wallpaper you need, it will not suffice to calculate the surface to be wallpapered. Firstly, roll dimensions in Europe are limited to 10.05m x 0.53m, which is why, for normal room heights, only three full lengths would result. Secondly, patterned wallpaper often requires the pattern repeat to be calculated, meaning cutting off excess paper. Depending on the type of pattern repeat, the excess paper cut off will have to be included in the calculation. Free matching wallpaper can be glued without consideration of the pattern, and can thus be cut continuously. There is practically no cut-off waste. For straight-matched patterns, the patterns of all strips are hung at the same height. When cutting the strips, they are laid out so that the motifs are right on top of each other. For small pattern repeats, cut-off waste is minimal. When working with an offset match pattern, the patterns between strips are offset. The measure of this offset is indicated on the wallpaper roll label along with the pattern repeat. For instance, the indication 64/32 on the label means a pattern repeat of 64cm and a motif offset between the left and right wallpaper edge of 32cm. Thus, cut-off waste will be, at most, as large as the indicated pattern repeat.
If the room has niches, slanted walls, dormers, or bays, these details must also be included in the calculation. On the other hand, the areas of windows and doors are not subtracted but simply disregarded when measuring.
Checking Delivered Wallpaper
Of course, it is obvious that you would check goods that you purchase yourself. However, in the enthusiasm of such a project, things tend to get overlooked. If delivered wallpaper rolls do not have the same batch number, they come from different production series and may exhibit differences in colour and structure. Repeat orders are also problematic for that reason; often, rolls from the same batch number are no longer in stock. In such a case, change the rolls in the corners of the room. The varying way in which light falls in corners can hide differences.
The “fan test” is suitable for obtaining random samples of colour uniformity. The wallpaper rolls are unrolled the length of a table and laid on top of each other, fanning them out.
Images & text courtesy of AS Creations, Wallpaper 1×1 – A Textbook For Craftsmen and Those Who Wish To Be