If you vanity is a standard type and not like the one pictured that fits more like a piece of furniture, than yes, seal all around the backsplash. Do not cut the beadboard.

Brutuses,
Every time I see a picture of your beautiful bathroom, it makes me smile! It is so appealing and just so soothing. I love everything about it!

Mary,
I saw the white ice beadboard in 4' x 8' sheets at Lowe's on sale. If you can reduce the height, you can get two 4' high wall sections out of each sheet.

Thanks, brutuses ... it's 48".... I was just adding the height of the baseboard and chair rail to make the point that it goes quite a bit above the 36" vanity. The point being -- should I even attach the backsplashes? It is a full cabinet (to the floor) vanity, so doesn't look like the photo above. However, like those vanities, I wonder wouldn't the PVC wainscoting be sufficient for backsplash and look "cleaner" as in that photo. I actually like the photo above, but you can see the vanity in the link below. It will be in the corner as many are -- upagainst both walls (hence the side splash).

Here is a link that might be useful: vanity

Thanks for the compliment Goldie.

Mary, I would definitely put the backsplash as it dresses up the vanity and you'll be glad not to have things constantly splashing on the beadboard even though it's PVC. It will be so much easier to wipe that backsplash than to be constantly wiping the wall with all those groves.

Are you setting your beadboard on top of the baseboard or behind it? We have our baseboard in front of the beadboard. The beadboard is 1" from the floor.

Thanks, brutuses ... it's 48".... I was just adding the height of the baseboard and chair rail to make the point that it goes quite a bit above the 36" vanity.

Just be careful-- when you get up to that height, you can very easily run into problems from light switches and outlets. Make sure the covers don't fall on the chair rail, or half on and off the beadboard.

Thanks, all -- Brutuses, I didn't realize that was your bathroom in the photo. Beautiful! love those vanities, and considered something similar, but our project is a small kids' bath and we need all the storage of a full cabinet vanity.

Goldie, actually it's the Lowes PVC that I got -- had them cut the planks in half for 48".

The baseboard is grooved specifically to hold the beadboard panels, so it's like a kit. Thanks Bill for the heads up. So far, it's so tall that it goes beyond the switches. My only concern now is for the mirror height. But I've seen lots of photos of mirror frames cutting into the wainscoting. Just trickier for an inexperienced DIY-er to get the cuts right so it doesn't look rough. Will need a friend's help with this -- any tips on working with PVC? Even the power saw at Lowes managed to split it at one point, sending out pieces of PVC...