Advanced Wallpaper Techniques
Once you know the basics of how to paste a strip of wallpaper to a wall and trim it to fit, then you're ready to learn the more advanced techniques required in papering a typical room.
But don't be intimidated by the word "advanced". Anyone who can paste and trim wallpaper can also master these techniques.
Soffits can either be papered on the front and the bottom or on the front alone. If you're just papering the front, simply hang the strips from the ceiling, leaving the bottom untrimmed until you've covered the whole soffit. Then you can trim the bottom all at once.
If you're doing both the front and the bottom of the soffit, you can treat it like an outside corner. If it's relatively plumb and square, you can hang the paper from the top where it meets the ceiling, wrap it around the front edge and carry it along the bottom of the soffit to the wall.
Do the whole soffit before you do the wall below and leave a 1/4-inch overlap along the wall. Then when you paper the wall, cut the top to cover that overlap and use vinyl-to-vinyl adhesive as needed to glue that seam.
If the soffit's not plumb and square, your strips will start going out of alignment when you try to wrap the front edge. In that case, paper the bottom of the soffit first, leaving overlaps along the top of the wall and along the front edge.
Then hang paper along the front of the soffit, pasting the overlaps with vinyl-to-vinyl adhesive as needed, and the rest of the wall after that.
Working Around Obstructions
If you come up to a light switch or outlet, turn the power off to that fixture, remove the cover plate, apply the paper, punch through the paper with a razor knife along one edge of the device and then cut along the edges to clear the opening.
For obstructions like plumbing pipes, lay out as much of the strip as you can up to the obstruction. Cut from the loose edge of the paper back to the obstruction and then cut the paper to fit around the obstruction as you lay the two sides of the cut paper in place. That'll leave a seam at your initial cut, but it should virtually disappear when you lay the two pieces back together and smooth them out.
A radiator can be a significant obstacle, especially trying to smooth the paper out behind it and determining where to cut the bottom. A yardstick might do the trick, though.
Once the paper's set above the radiator, angle the yardstick in behind the radiator and use it to lightly press the paper against the wall. Then use the far end of it to crease the paper where it hits the base molding or the floor if there is no molding. Pry the paper back up, cut along the crease and then use the yardstick to press the paper more firmly against the wall.
Wallpaper can be used to good effect on the lower half of a wall in a wainscoting treatment.
The basic hanging principles are the same as for a full wall. But before marking plumb lines to guide the edges of the paper, you need to mark a level line across the wall to show where the top of the paper should hit. Then you need to cut the top of each strip to line up with that line.
An alternative would be to first install a piece of appropriate molding at the desired height and to then trim the wallpaper to the proper height below that.
With borders, the hanging principles are basically the same as for regular wallcoverings, but they're usually a bit more difficult to deal with.
They come in lengths long enough to run from corner to corner, and it's best to hang them in one piece, with overlapping seams at the corners. So you end up pasting and booking long sections at a time.
Just fold those together like an accordion, lapping the pasted sides together as when booking regular wallcoverings, and unfold them as you apply them to the wall.
If you're hanging a vinyl border over a vinyl wallpaper, either along the ceiling or at chair rail height, you'll need to use that vinyl-to-vinyl adhesive all along the border to make it stick.
If you have to join 2 pieces together in the middle of a wall, the easiest way to make the seam is to cut the two pieces extra long, overlap the ends where they meet till you match the pattern exactly, double cut the ends at the least conspicuous point, pull up the ends to remove the waste and smooth out the seam.
If you're papering both sides of an arch as well as the inside edge, first hang the paper on the two sides of the wall, letting the edges hang loose in the archway and trim the loose edges back to within an inch of the arch.
Then in the arched area, make a series of cuts in the edge of the paper every 1/2-inch or so to the edge of the arch. That lets you fold the paper over the inside edge of the arch, creating an overlap.
Cut as many pieces as needed to the width of the arch minus 1/4-inch to cover the inside edge and set those in place, leaving 1/8-inch or so gaps on each side to prevent fraying. Be sure to use vinyl-to-vinyl adhesive where it's appropriate.