Baseboards are often installed before flooring since they must be finished in place with either stain or paint and this is much easier without worrying about staining the hardwood tile or carpet.
Install moulding before carpet.
For things like tile or hardwood you would want to give a to inch clearance for the installers to be able to put the flooring in and be able to slide the edges beneath the baseboards.
Determine the type of corner at the opposite end of the wall then cut the necessary inside or outside angle.
The first cut will mirror the corner cut of the molding already installed.
Or you may be replacing the baseboards but leaving the carpet.
Install the carpet install the carpet all the way against the wall.
Install subsequent baseboards using this procedure.
The carpet installer can run the tack strip up to the trim then roll excess carpet under the trim.
Fasten the molding with nails.
If adding baseboards after carpet is laid it should be installed at the same height as without carpet.
Baseboard first set on 3 8 wood lath strips tack less set between 3 8 1 2 inch away padding brought up to tack less and carpet installed and stretched over tack less and tucked under base.
Oftentimes it is best to install the baseboards after the carpet is installed simply because of these tack strips.
Then touch up base if need be.
Measure the length of a wall adjacent to the finished wall.
A really thick shag carpet can make it difficult to judge how high to place the trim.
If you plan to install baseboard moulding before adding carpet it needs to be installed 1 inch above floor level to allow room for both pad and carpet.
However consult with your installer to be.
This is because when installing the baseboards after carpet installation they tend to wedge the carpet in between the tack strips and baseboards like a vice.
For most installers this is not a problem and can be done easily.
When installing baseboards before carpet ask the installer how large of a gap to leave between the floor and the trim e g.
The trimmer is not going to make a special trip back to install the base after carpet is installed.