Wallpapering Inside and Outside Corners

Inside and outside corners are the more difficult parts of hanging wallpaper. By themselves they are not difficult but it is usually the case that corners are not true plum or vertical. Therefore this is where it becomes difficult.

You have to be able to hang the wallpaper plum, even if it is the case where the corners are not. This can be a hard task so you should take it slowly and do the job with great care.
Inside Corners

You need to measure the distances from the strip of wallpaper next to the corner to the actual corner itself at both the top and bottom of the wall. You should add one inch to the larger of the two measurements and then cut a sheet lengthwise to this measurement. If it is the case that this measurement is within 6" of the full sheet measurement you should use a full sheet of wallpaper. If there is a sheet that is next to the corner, the edge of it can be used as a plum line.

But if there is not a sheet at the corner you only have to measure out from the corner, at dimensions of a roll of wallpaper less than one inch, for an overlapping corner, and then draw a plum line. This line you make will guide you when you hang your primary sheet. Generally the first sheet you hang will be in a non-conspicuous corner, you will use this process when installing the first sheet of wallpaper.

Next step is to hang the sheet, described earlier, and then wrap the extra wallpaper into the corner. Typically corners are not perfectly plumb so you will have to strike a plumb line on the adjacent wall. Again this should be at a distance from the corner of one inch less than the dimension of the wallpaper roll. Now apply another sheet and wrap the excess so that it will overlap the first sheet. Next you take a broad knife or razor knife and cut the overlapping sheets in the corner. Now peel away the two extra pieces.
Outside Corners

If it is the case where the outside corner is exactly plumb, which is not often, you can wrap the wallpaper around the corner and then begin from its edge on the other side of the corner. But if the outside corner is not plumb you need to be a little more careful and give it more attention.

Just like with inside corners you should measure at the wall's top and bottom, the distance from the last sheet to the corner. Add one inch to the measurement that is longer and then cut a sheet that exact size. If the measurement you took is within 6" of an entire sheet, you need to use a full sheet. You can hang this sheet and cut a diagonal slit at the top corner in order for it to bend around the corner.

Make sure to hang it so the paper is smooth and then fold it smoothly around the corner. Next you will have to have another plumb line on the intersecting wall. In order to accomplish this strike a plumb line on the intersecting wall with a wallpaper level. The plumb line you make should be the width of the roll from the corner.

Next you can hang the intersecting piece to the plumb line you made. When both pieces are in place you can make a new plumb line 1/4"- 1/2"  from the corner on the side of the corner. Where this line is you need to cut both pieces of wallpaper and then peel away the extra wallpaper.

Author: Jason Green