Hi All:
I need some help thinking about what things to consider before we pour a slab.
Wife & I are building (maybe attempting to build would be more accurate) a new house. Northern MN. After years of DYI, I am attempting to be the GC & having a fun time (don’t ask me about architects and well drilling/hydro-fracking!). The house site is on ledge rock, so the plan is for a footer pinned to the ledge, a short (3 course) block stem wall and then the concrete slab. We are planning on hydronic radiant floor heat for the first floor. The slab will be insulated and a vapor barrier installed (ala’ the online article on floor heat at the FHB site).
My real concern is that our plans call for a kitchen sink in the island. I know we will need a drain line set before the pour, but what about supply lines? I would like to have a “home-run†PEX system. Is it overkill to layout, say 1 ½â€ pvc as “conduits†for both the hot and cold PEX lines to the island, or would you just lay the PEX under the slab (under the insulation) and go for it…..Opinions – thoughts? In the same light, would you run conduit for the wiring, or just lay under the slab?
Do you all have any other “Gee I should have done that before we poured the slab†ideas?
I am sure my plumber will have a preferred way on the supply lines, but as they say, knowledge is power….
Thanks…..
Pinemarten
Replies
Don't forget any floor drains by W/D and even by the DW if you choose. Or Water Heater. Or garage floor.
You also need electric. You will have outlets on the island. Possible a disposal, dishwasher, and/or switches for some lights.
Conduit and plastic pipe are cheap compared to sawcutting and patching a slab. In commercial buildings we don't run plastic water lines. Copper with a foam sleeve where it comes up through the stone base and slab will isolate it from abrasion. Haven't had to replace many of those.
Eric
Thanks for the thoughts.
Did not think about a floor drain for the DW. Could save a a lot of headache.
My thinking is some sort of conduit for the H20 supply runs is cheap insurance, but was wondering if my subs would look at me like I was from Mars for suggesting it. Is 3/4" PEX flexible enough to make a 90 degree bend inside a 1 1/2" PVC pipe, or should the PVC conduit "sweep" up? I guessing I also need separate conduit runs for hot & cold to minimize heat transfer.
Did not think about light switches either, only power for the DW, outlets, etc. Might need a bigger electrical conduit.
Any more words of wisdom?
Pinemarten
>Is 3/4" PEX flexible enough to make a 90 degree bend inside a 1 1/2" PVC pipe, or should the PVC conduit "sweep" up?
Absolutely not, especially if you're trying to snake it through. I'd go to at least 2" and sweep the curves. I can curve the 3/4 pex to about a 6" radius on open ground. Pushing it through a pipe won't be as easy. You're using gray electrical conduit as the chase, right? Not the white plumbers pipe. Other's might have even better numbers for you. Try an experiment before you bury the pipe in concrete.
In a similar situation we ran three conduits and a pipe to the general location. The plumber ran a drain pipe, I think it was 1-1/2", for possible sink drainage. I ran three 2" conduits with large radius, about 2' rad, sweeps for any water supplies, they had a central RO unit in the garage, and small appliance branch circuits and a possible stove top and/or oven. There was even talk of a needing gas. The other end was in a utility room off the garage. The HO didn't know what was needed. His wife couldn't decide. The general needed a solution to keep the ball rolling.
The three conduits gave a lot of flexability. As it turned out the plumber pulled in, PEX I think, a hot and cold and I only had to pull in a single circuit. If, at a later date, the HO wanted to change things they will be all set. The conduits end an inch or so above finish floor under the cabinet bottom. The carpenters rigged up a nice removable floor in the cabinet so everything is accessable. The actual cost was about $300. The HO was happy to see the job move forward.
Edit to corect number of conduits. After installing two we decided to add another when gas piping became a potential issue.
Edited 9/14/2002 10:11:54 PM ET by 4LORN1
You're on the right track...good advice so far.
For the island w sink, you'll need hot supply, cold supply, drain pipe...and don't forget the vent unless your code allows a wet vent. Look at studor vents. As already mentioned you'll need at least 20A electrical for island outlets.
If you think you'll ever have a cooktop on the island, you'll need an additional 220 electrical if the cooktop is electric, or a LP/gas run if it's propane/gas. Will there ever be an overhead vent over the possible cooktop on that island? Is so, plan for a dead-end run of romex in the ceiling overhead to power the fan/lights, as well as ductwork (8" round minimum is a large BTU cooktop) for the vent.
Burying things now is easy. Remodeling later will cost 10X what the installation will cost today with your open framing.
Without a doubt use separate conduit with large-radius sweeps instead of traditional 90s for pulling PEX and 12ga electrical.
For the slab, take a really close look at your floorplan. Mark up the plans to show all appliance, fixture, and electrical run locations. Think about how you'll supply, and how you'll drain/vent these theings.
Put your plans away and look at them with a fresh brain another day.
As others have mentioned, conduit is cheap and easy. Diamond blades and jackhammers are a pain.
I don't now what the lengths of your conduit will be, but...if pull ropes aren't set when the conduit is installed, a really easy way to set the pull rope is to start with fishing line (or a real lightweight braided pull line if you have access to one) and a wad of cotton or something similar. Tie the cotton to the end of the line and stuff it in one end of the conduit. Put the hose of a shop vac on the other end of the conduit. Works like a champ. Used it several times on underground street-to-house utility runs up to 600' long. The first lightweight line pulls the second heavier line, the second pulls the PEX or electrical, etc.
There are also load losses (possible overheating) when many conductors are run in long lengths of conduit. Shouldn't be a factor in your case, but discuss it with your electrician for a warm/fuzzy.
As (was it Cloud?) was already mentioned, use the proper conduit for each application.
To answer you other question..."is it overkill...". When building on a slab, it is possible, but very difficult, to overplan what you need for utilities. It really is a case where "mo is bedda."
run the supply, drain, elrectrical conduit close to area for island. Have a blockout in slab under island. once you start hooking everything up, you can pour the blockout with bag cement. This way you can be close on measurement and have area to play.
Thanks to all for the hints. I don't get to visit as often as I like, so the delay.
One further question: Cloud wrote:
"You're using gray electrical conduit as the chase, right? Not the white plumbers pipe."
I was planning on gray for the electric chase, but white for H20 supply. Should I use gray for everything & why?
Thanks..
As a conduit for running the PEX, the grey we used had big sweeps on teh elbows, whereas the white didn't. Wouldn't want to try to make PEX take a sharp 90.
Thanks. I knew there was a reason. Gray it is!
White PVC should never be used as electrical conduit under any circumstances. It is a code viol;ation in some jurisdictions because it would be pretty easy for someone doing plumbing repairs to think it was a water line, and the results could be tragic.
Admittedly, in this case, the chances of that are remote, but worth thinking about anyway.
Another way to get a little wiggle room on your rough-in is to wrap all of the pipe coming up through the slab in a couple turns of sill sealer. (That's the foam strip you put under the bottom plate.)
It will protect the pipe, and you can rip it out and get a little movement out of the pipe if you need to.
Worst case, if you have to get out the chipping hammer, the pipe is away from the concrete by enough to avoid damage.
DRC
Another approach --
How about a utility tunnel? If the floor can accommodate a removable top, you might have a 12" x 12" or something like that tunnel that you can access from above by taking out some screws or something. They do this all the time in film developing labs. The trick for a kitchen is coming up with a floor design that lets you hide the edges of the access panels. Or if the rock leaves you room enough, you could go really big and make a tunnel that you could enter from one end and work in -- sort of re-inventing the crawl space.
-- J.S.
Utility tunnel? No, don't do that. You'll be depriving future plumber repairmen of their wages since you wont have to call them in to fix the lines when the slab shifts.Half of good living is staying out of bad situations.
Forget the primal scream, just Roar!
> You'll be depriving future plumber repairmen of their wages
Or you could make it worth their while by hiding your valuables in the utility tunnel and then forgetting where you put them.... ;-)
-- J.S.
Thanks again - I am amazed at the number of good ideas that "pour" in. A utility tunnel...now there is an idea. How to construct? Maybe just place a large (10" or larger) white pvc and "block out" the area in the mechanical room and under the kitchen island and finish the slab in these areas with a bag mix as was suggested.
With regards to the gray PVC. I went to the local "big box" last night and did a test. They had short sections of 3/4" PEX (8') and I grabbed a 2" gray PVC "sweep".
The PEX fed through the sweep without a hitch. Cool.
Thanks
Pinemarten