Expert: Dan Griffin - 3/24/2009

Question
QUESTION: Dan I want to install a washer/ dryer in a second story (top floor) apartment.  As this apartment does not have any gable ends and the apartment directly below it is also getting a washer/dryer installation, I thought the best way to vent was to go down through the floor into the ceiling of the first floor and then to the outside back wall. The second floor has a lightweight concrete on top of wood. I have to drill/cut a 4" hole through that concrete that is below the 6" service wall (where the bathroom stack/vent is). I also have to drill/cut 2-1" holes through that concrete for the electrical to the lower floor.  What would be the best way to get those holes cut  Many Thanks Carol

ANSWER: Carol, are you planning to do the work yourself?  There are seveal drills that will work on the light weight concrete.  There are dry cut diamond core bits and carbide core bits, but these are far too expensive for your limited use.  A plumber may have the drill and bits.   It is very possible to drill a series of small holes all around the penetration and break out the center and can be pretty fast.  It is also possible to just pick away at the light weight and peck a hole through it.  The 1" holes are easy, both an electrician or plumber will have that size, though, again, you can peck out that size also.

Carol, the big deal here is that the plumber might need to get a plumbing vent tied back into the stack or through the roof above your space.  If this comes up, suggest a Studor vent (air admittance valve).  Make sure you also plan on hot and cold water.  The dryer vent is very limited on fittings and distance.  There are inline booster fans that can be used.

---------- FOLLOW-UP ----------

QUESTION: Dan:  Wow! Thanks for your quick answer.  The washer drain will be tied into the existing 3" stack that is 2' away. The dryer vent has a vertical run of 3' then a horizontal run of 12' to the outside.  I think 4" solid (not flex) duct should be okay here (screwed and foil taped).  By the way, yes this girl has done this type of thing before ;)  I was hoping for a magic bullet in going thru this concrete floor.   I have to cut through the aged vinyl siding to put the 2 4" dryer vents in.  I am thinking that a very hot hair dryer on that cold vinyl siding before cutting with tin snips should prevent the siding from shattering.  Thoughts.   Many Thanks Carol

Answer
Carol, I'm impressed.  You're right,the vinyl siding will probably be old and brittle.  If there were any way to borrow a hole saw I think your chances would be better, even then I would run the bit in reverse at least to start.  You should be able to rub the bit in reverse through the vinyl, then forward through the sheathing.   Warming the vinyl can't hurt.  Smooth wall tin is much better than the krinkle wall or vinyl stuff.  Be very sparing about using screws though as the sharp tips really catch lint - short pop rivets might be better, at least keep them out of the bottom.   Finish off with  foil tape on the joints and plenty of hanging straps to keep pressure and movement away from the joints.

Check how far your dryer can push - different brands use different numbers, but most residential dryers can go about 25 feet.  Each bend or turn counts as 5 feet so you have 2 bends and 15 feet of pipe, you're at the limit unless your dryer can push farher.  Some can make 40', but I may be thinking of a commercial unit.