My floor measures out at 296 sq ft, but the carpet company wants to charge me for 330 sq ft. Their reasoning is that they are not charging me for the actual square feet of total area, but for the carpet they are bringing with them to do the job which includes the remnants that will be left over. Is this typical or are there shady happenings?
It's totally normal. Carpet comes on rolls in widths from 11'6" to 13'. They need to cut off a chunk of that roll to fit the room.
It's the reason why if you're carpeting a 10x10' room, you can't buy 100sqft of carpet: they'll charge you for more like 120sqft (12' roll, 10' long).
It also depends on the layout of the room, and where they put seams (if necessary). Eg: an L-shaped room has a couple different ways to lay out the carpet, and depending the layout and where the seams are, you'll use a different amount.
A good installer will also consider traffic: if there are seams, you don't want them right in front of a door way, or preferably not running down the middle of a high traffic pathway. I think they also avoid putting seams within a foot or so of walls (so there isn't a narrow strip of carpet running along the wall). All of these things may end up using more carpet than a layout optimized just to minimize scrap, but will result in a much better looking and longer lasting install.
The other factor is in patterned carpets, they will use a bit more since the patterns need to line up. The bigger the pattern, the more is scrap needed to keep it in line.
The important bit is to keep the scrap carpet, unless you really don't need it, since you paid for it. Often there is a good size chunk, which can be used for many things:
- Large door mat
- In front of fire places
- Padding for moving/storage
- Google has many more
They're billing you for their actual materials cost this way. It's not a made-up number. In the end, though, the final price is what matters, not how they come up with it.
Get more than one estimate. Prices of work on your house vary widely, as does quality of work, and the two are not always linked.
They're charging you for the carpet which they will actually dispense and consume to do the job, which, as others have stated, will usually be more than the measured size of the room. Consider it like cloth; if you need a square yard of cloth from a bolt at a craft store, you usually have to buy a yard of the full bolt width, which can be up to 3 times the area you actually need for certain types of cloth. This is because the craft store cannot re-sell your waste to anyone else, so they either eat it or charge you for it. Guess which one is more likely?
Your better carpet guys will minimize the slack at the edges after stretching, but you can still expect to pay them for about a 6" strip along at least two walls of the room. They'll also need enough slack to lay down and seam through doorways, which will be wasted along the rest of that wall, Your better carpet guys will also be able to make the best use of the carpet you're paying for; if you're carpeting a 10x10 room and they have a 16' roll, they'll cut the carpet for the 10' width, then use the remaining 5-6' cutoff for the hallway outside if you're carpeting that as well, or for an 18-20' room.
If there are any sizeable remnants they're charging you for, make sure they leave them behind; as other answers have stated, they can be put to use as doormats, in closets, and even to patch holes if you know how to seam carpet.
Charging for actual materials used is totally normal - suppose they would only do the installation and you would buy the carpet yourself - you'd have to buy a bit extra to compensate for seams, rooms being non-rectangular, etc.
Another example is a countertop - they are usually rectangular, but you have to cut huge windows to install the sink and the cooker - parts you cut out seem to not be participating in the final installation but you have to pay for the entire countertop. Parts cut out can be used elsewhere - same comes for the carpet leftover which can be used for patching worn out parts.