Under Slab Plumbing

bayview · August 28, 2008, 06:35:32 AM

I am about ready to do the "rough in plumbing" on a small cabin. (16X20)

Would you be concerned about using cpvc under a concrete slab with all those fittings? . . . ( 90s, Tees, couplings, etc.)

I was wanting to use pex, but am unable to rent a crimper. Crimper at Lowes is about $160.00. More than the cost of all the rough plumbing.

Is CPVC ok under a slab? Or should I (bite the bullet) and purchase the crimper so I can use pex.

MikeT · August 28, 2008, 07:43:08 AM

I just bought this online: http://www.pexcrimper.com/

Price is right. It seems like it should hold. I received it in the mail last week--it is quite hefty and solid.

mt

August 28, 2008, 09:27:37 AM

Under slab I wouldn't use it. When it breaks you will tear your walls out to re-plumb from above. I'd do the Pex with no underslab connections if it was me.

MountainDon · August 28, 2008, 09:30:23 AM

I live in a house on a slab on top of the plumbing. My whole neighborhood is built that way; heck 99 44/100ths of the city I live in is built that way. My thoughts on plumbing under a slab is that a slab is no place for there to be any connectors at all. In fact, I'm not certain, but I believe around here it is not allowed in a potable water system.

I would buy a good crimper and call part of the cost of building on my own. It's still cheaper for you to buy a good crimper than to hire a plumber.

Lots of sources out there. If I was buying a tool I'd go for a Wirsbo type. But there are two other choices for good tools as well. One uses stainless steel bands, the other copper bands

One source is... http://www.pexsupply.com/CategoryPre.asp?cID=544&brandid=

They have the SSC tool for $80 at present. The Wirsbo type (expander) is more expensive.

Another recommended source is... http://www.houseneeds.com/shop/plumbing/pexcrimptoolbuy.asp

One thing to remember when using the type with the standard copper crimping rings is to be certain to use a go-no go gauge to be absolutely certain the band is crimped enough. One of the easrly failures that was run into with polybutylene was that work crews got sloppy and didn't gauge all their crimped fittings. That led to undercrimped joints and leaks. On ocassion it also led to over crimped bands and some of those bands snapped after being in service a short time. I had one of those that showed up early.

The SSC tool will do multiple tubing sizes, the others have heads or inserts that are matched to tubing size.

MountainDon · August 28, 2008, 09:33:48 AM

Glenn snuck in there before I was done...

I want to add that I've seen the floors of a couple of homes jack hammered open to repair an under slab leak. It's not something I'd ever want to deal with. It was bad enough having to have holes cut in the walls. At least the ceramic and porcelain tile floors did not need to be cut open.

August 28, 2008, 09:40:02 AM

At least I agreed with you. I've seen lots of new commercial floors cut up for booboo's and changes also. I like the Wirsbo tool best also.

I prefer the shrink back to fit rather than the pushed in to fit. May just be me but it seems more reliable. I spent around $300 for my tool with 1/2 3/4 and 1" dies.

Even that is cheaper than a plumber. ...and I don't think we'll cut into Scott's business - and we are not picking on good plumbers.

We actually are taking over the job of all of the trades in most cases to our benefit.

bayview · August 28, 2008, 04:36:33 PM

Thanks for all your responses. . .

I'll scrap the under the slab CPVC. I would hate to do any under slab repairs. I'm still stuck on wanting to use the CPVC since I'm accustomed to cleaning and glueing PVC.

Roof trusses have been built. . . The cushion sand has been spread, barter boards and lines are up. I am hoping to get plumbing done this weekend and the concrete contractor within the next week or two.

Here is the floor plan that I am working with.
https://i38.photobucket.com/albums/e149/bayviewps/16%20X%2020/16X20.jpg

The property is about 35 miles NE of the Prez's Crawford Ranch. So not a big fear of of long term freezing weather.

I have a straight shot for the sewer from the toilet towards the septic.

The water heater will be in a corner cabinet in the kitchen.

The exterior walls will be 6". Would it be feasible to run the lines in the exterior wall? I then would only have one fitting under the slab coming from outside and up to the water heater. Running the plumbing completely around the tub and toilet and coming in on the inside wall to the bath sink. Would I notch or drill the wall studs? Should I insulate the plumbing?

Your help is greatly appreciated.

glenn kangiser · August 28, 2008, 05:01:20 PM

I'll put it here so it's easy to see.

I prefer drilling when I do it. I don't do it often so am not up on all the details. The PEX is very easy to pull through drilled holes. I haven't used the CPVC.

ScottA · August 28, 2008, 05:05:16 PM

Take it from a plumber. Rent the crimper or buy one.

August 28, 2008, 05:06:45 PM

I was hoping you would show up.

There are also compression fittings and Shark Bite fittings that work on PEX but a bit expensive.

MountainDon · August 28, 2008, 05:45:18 PM

I believe those fittings might be good for a small quick add-on or repair/replacement... but if you buy the tool now you'll have it when that time comes around and avoid the expensive fittings.

Redoverfarm · August 28, 2008, 05:51:05 PM

Glenn I wish my plumbing was so easy as your diagram.

glenn kangiser · August 28, 2008, 05:53:25 PM

That's bayviewps floor plan with plumbing , but you are right - it's never as easy as it looks, is it?

MountainDon · August 28, 2008, 05:59:05 PM

But let me add that with PEX it is almost as easy as it looks. Our repipe was basically plumbed in a day. Most of the time was spent in prep (cutting open walls) and in finish (replacing drywall cutouts, taping, tecturing and painting.

Also I I could use PVC or CPVC, copper or even galvanized pipe... I've done all. But I'm actually looking forward to doing the cabin in PEX. I'm additionally lucky with Frank being willing and ready to loan me his PEX crimper.

PS I'll be using a little bit of copper to make up a few things I want, but it'll be a breeze pulling PEX from here to there. It's more like wiring than plumbing. In fact I found myself thinking in terms of the kitchen circuit, the shower circuit...

August 28, 2008, 06:29:49 PM

Interesting - I think of electricity being like water.

Redoverfarm · August 28, 2008, 06:31:24 PM

Just as long as you know the difference. Usually not compatable.

glenn kangiser · August 28, 2008, 06:34:53 PM

That's what they tell me but I've been welding standing in water for years.

Sometimes it was a little hard to hold on to the stinger though. I guess that's why they call it a stinger.