When I put my bookshelves on top of the cabinets and secured them to the back wall I notices that I had gaps ranging from a 1/16th of an inch to .5in. This did not make me happy. At the time the only way I thought I could compensate for this was to use filler (Rope Caulk) and white acrylic silicone all purpose caulk. What I didn't realize was how difficult it was going to be to fill these voids with rope caulk and white acrylic caulk. Looking back, I should have cut wood strips and used them as filler as it would have been much easier and cleaner. The technique I used worked but it was much fussier to deal with. The Rope Caulk is like putty and it fills the gap but needs to be smooth because it is easy to get bumps and uneven spots. These bumps and uneven spots will show up when you put the silicone based caulk over top of it. I would highly recommend using wood as a filler and then using the silicone caulk, your installation will be much better. Even if it takes a bit more time to cut the strips of wood, it will save you time in the long run.

Once the bookshelves were in installed I needed to nail in the trim at the top of the cabinet to match the fireplace mantel. This was rather easy to do and was done in just a few minutes. At this point everything was installed, nailed, caulked and primed. The last step was to give it a final paint job. This was the moment I had been waiting for for a long time.