Question on drain vent through corrugated metal

[green.bubbly]

This is actually a plumbing question so I did not know where to post it.




First off, I called my inspector for my open wall electrical inspection this morning. He hit me with depressing news. They prefer to do all the open walls at the same time. I was really trying to get the electrical inspection done so I could use the upcoming three day weekend to put up the interior wall sheathing.


So my plumbing and air conditioning needs to be done as well. Pretty straight forward on the plumbing. One cold water pex coming out the slab and one simple drain pipe. A/C is nothing terribly hard either. I just only have a few hours after work Wednesday and Thursday night so I can get the inspector out on Friday.

Problem one. I need to drill a 2.5 inch hole through three girts for the vent pipe. There has to be an easier way of drilling this size hole through metal??? I got one drilled but it was not fun. I used a hole saw bit like below which is made for wood of course. First issue is that as soon as the large hole bit hit the metal, it would bind and bend or break the center drill bit.

After three more bits, I ran out and ended up sticking a screw driver through the hole and into the hole saw bit. That actually worked a little better since the screw driver could flex without bending or breaking. But is there a better way?

Second question is on the drain vent. I want it to come out the back wall which is PBR steel siding. Anyone have any suggestions on flashing this? A regular roof flashing vent like below would more or less work if I could find one that is small enough to fit between the ridges of the PBR panel.


I actually just found this online at Lowes.com. If it is indeed 4" wide then that may work. Any other suggestions?

 

[brewchief]

The style flashing you are show will work even if it's wider, those are designed to bend over the ribs on metal roofs, a little sealer on the back then screw it down and your good.


On a side wall I wouldn't bother with a flashing unless it was in a spot that would see a lot of water, cut the hole the right size and just use some good caulk.

 

[green.bubbly]

Thanks. I might go with just the caulk. I think the flashing would just end up being ugly unless it is really small.

 

[csp]

For your bit breaking, if the center hole is already drilled in the metal pull the hole saw out and swap the center bit out for a piece of round stock metal the same size as the bit. There won't be anything to bind anymore and it also prevents the center hole from wallowing out and keeps the overall hole the correct size.

 

[texasguy]

green,

I've used the lenox bi-metal saw through pbr with xlnt results - I just put in a 2 1/8" hole for meter/electrical panel. The fit was clean and tight and I gave it a light hit of expanding foam - it is hidden behind the panel so appearance was not of highest concern - for something more visible, caulk would be fine. I have used only smaller step bits for girts - you might see if such thing as a 2.5" step bit exists - I couldn't find one using the google.

These are better for thicker material:

http://www.holecutterstore.com/xcar...r-sheet-metal-stainless-iron-brass-p-189.html


or you can go to a 2.5 knockout punch but warning - they are expensive for a seldom-used tool. You might check rental tool places or see if a local plumber / sheet metal fabricator will loan/rent you one.


I agree with csp's idea on the bit. you might also consider clamping a 2x4 or 2x6 under the girt where you are drilling which should help provide some stability and will also ease the breakout at the end of the cut. position it so you actually cut into the 2x.

 

[green.bubbly]

For your bit breaking, if the center hole is already drilled in the metal pull the hole saw out and swap the center bit out for a piece of round stock metal the same size as the bit. There won't be anything to bind anymore and it also prevents the center hole from wallowing out and keeps the overall hole the correct size.

This is basically what I did with my screw driver. It worked surprisingly better than a drill bit.

green,

I've used the lenox bi-metal saw through pbr with xlnt results - I just put in a 2 1/8" hole for meter/electrical panel. The fit was clean and tight and I gave it a light hit of expanding foam - it is hidden behind the panel so appearance was not of highest concern - for something more visible, caulk would be fine. I have used only smaller step bits for girts - you might see if such thing as a 2.5" step bit exists - I couldn't find one using the google.

These are better for thicker material:

http://www.holecutterstore.com/xcar...r-sheet-metal-stainless-iron-brass-p-189.html


or you can go to a 2.5 knockout punch but warning - they are expensive for a seldom-used tool. You might check rental tool places or see if a local plumber / sheet metal fabricator will loan/rent you one.


I agree with csp's idea on the bit. you might also consider clamping a 2x4 or 2x6 under the girt where you are drilling which should help provide some stability and will also ease the breakout at the end of the cut. position it so you actually cut into the 2x.

I checked around our local rental stores and they did not have a punch machine. I like the 2x4 idea. If nothing else, it make quiet the horrible vibration noise when drilling.

I like that cutter you linked. That looks like the ticket. I only have two holes left on my garage but I will have plenty to drill on my steel house. That might be well worth the $45.00 investment.


Thanks