"v" wrote in message

And if the section breaks, it will be a big trouble.

Why so?

Sheetrock work is not so much hard as time consuming.

Open the wall and ceiling as needed and fix it. Not a big deal.
Rather than make a lot of trouble for yourself trying to work thru a
small hole, I'd suggest opeing up from stud to stud (or joist to
joist) and then you have big area to work in, and can easily
nail.screw the replacement pieces of wallboard back in.

In my downstairs laundry/bathroom the dryer vent is in the wall. I've had a
couple of problems with it. Instead of drywall patching, I screwed a piece
of masonite over the opening and painted it along with the wall. Easy
access and hardly noticeable.

On another wall I have an opening from when the shower valve had to be
replaced. It has a mirror over it and is easily removed if I ever have to
get to it again.
Ed

http://pages.cthome.net/edhome