New Interior Wall (Non-Load Bearing)

I need to build a “room within a room” on the second floor of an office building. The new walls will not be load bearing and the first story has enough interior partitions that I am not concerned with any sagging of the 1st floor ceiling. Here is my question: The current large room has wall to wall carpeting. Can I place the lowere plate of the new walls on the carpeting, thus eliminating the need to restretch and tack strip the carpeting or do I need to cut the carpeting away to the sub floor. The wall to ceiling joints will have crown molding, so small settling cracks at the ceiling to wall interface would not be a problem.
Replies
What kind of carpet? If it is traditional short pile commercial carpet, it happens all the time. Not saying it's right, but it is done. If there is pad, that's too thick. Oh, you said stretched ... usually I see it over glue-down carpet.
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Use screws with at least 1" of smooth shank near the head and screw the bottom plate down with 2 screws per bay (8" OC.)
This will compress the carpet and foam to all but a very small fraction of their limit and any additional compaction over time will not be enough to notice.
Alternatively, you can use two flat head screws through the carpet under each stud as standoffs, then use one screw thru the plate next to each stud. This will prevent compressing the carpet any at all.
SamT
Anyone who doesn't take truth seriously in small matters cannot be trusted in large ones either. [Einstein] Tks, BossHogg.
Is a rule I always remove the carpet from the plate area and most likely you will be installing sheet rock and painting the surface so pulling back the carpet will also save the carpet from any damage. A carpet installer is not that expensive so call up a carpet store and ask to speak to one of there installers for a quote and add it on to your cost. Pass it on. (use drops to protect the floor.)
Screw the bottom plate down with a couple screws, run your layout, place 2 additional screws at each stud. Plumb up at each end, cut and screw top plate in place either to ceiling joists or use pairs of diverging or converging screws into the drywall (if it's a drywall ceiling.) Cut studs snug but not tight enough to deflect the ceiling, hang and finish, trim and done.
Perhaps it's best to think of this as a temporary wall in which case leaving the carpet intact may be a benefit.
Lance
I see a lot of comments about screwing the botom plate down..
Odds are 50/50 that you would unravel carpet fibres that way.
If I had to do what you say, I would place plastic first over whole area, then shoot the plates down through the plastic, then build the walls, cutting the plastic loose after all is done.
I have a concern about an other assumption you made though. The first floor has partition walls. In plenty of commercial jobs, that means that they are below the gypsum cieling down there and have no structural connection whatsoever to the floor structure. That structure needs to holdthis load or not all alone. If it does have much deflection, you will see it in the cieling below
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On many of the commercial jobs I have dealt with the carpet was laid and then the partition walls were installed with no fasteners into the floor at all. The idea being that changes to the offices did not necessitate re-flooring.
Why a room within a room? Is it for sound isolation?
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