conduit question...

[eeprete]

I'll be running conduit under a huge concrete slab and have started by preparing a ditch alongside my garage.

Is it better to break the concrete close to the house and bring it up to above grade, enter the house, then back down, or, is it better to simply enter/exit the house below grade underneath all of the slab with the expectation I should make every effort to ensure it is sealed shut.

Slab is in very good shape, about 10-12 yrs ago. My trench is about 21" deep and I've started to tunnel out under the slab (sledgehammer and PVC tube method). In an effort to stay on the direction course I've litererally only been tunnel 3-4 inches at a time. Are there any proximity devices that can be used so I can tell whether my conduit is on course or off-course, either from above at the slab or from inside my basement?

My drawing is slightly off as my target area is dead center between the bilco doors and back steps.

https://scontent-a-ord.**.fbcdn.net/hphotos-xap1/t1.0-9/10457876_10152222485048823_65502120085974817_n.jpg

 

[Mustang51js]

If you go below grade you have a good chance of water leaking into the foundation, I would go up if you can when entering the house.

 

[eeprete]

The soil under the slab has been very dry and there is also almost a 2 foot roof overhang so while I understand the concern not sure I run an enormous risk. I've been considering breaking out a 2x2 square then repouring that small area and getting trim bricks to define the separation that will match the other stone trimmings. I can't seem to find anything definitive re code either. I look at it this way, screwing up the slab runs a lesser risk than if I did something to the foundation...

 

[69gp]

First reply here. you could use this type of fitting going through a concrete wall below grade. I guarantee you will not get water in your basement if you use the seal listed below. Or what you could do is when you drill or core through the wall go a little over sized and pitch the hole going downwards from inside the house heading out. then seal with hydraulic cement. i have used and done both methods and have had good results.

http://www.emersonindustrial.com/en...ru-wall-floor-seals/thru-wall-floor-seals.pdf


steve

 

[69gp]

on a quick note after looking at your drawing can you drill the foundation first and then drive a rigid conduit through the wall and under the slab?

 

[eeprete]

on a quick note after looking at your drawing can you drill the foundation first and then drive a rigid conduit through the wall and under the slab?

Yes, and funny you ask as that's how my father said to do it. I've actually burrowed out about 19 feet so far out of 21 though.

 

[69gp]

yeah fathers Know best

 

[SLYDIT]

i once thrusted a 1" steel pipe under a driveway with a sledge hammer, then drew it out and pushed a 3/4" conduit in its place.

 

[eeprete]

That's sort of the plan slydit. Have reamed the hole plenty, overcome a minor interference halfway through and now I'm close to the other side. I estimate now about 6-12". I'm hittining something now, perhaps slag concrete from the patio or foundation? Prefer not to break through the foundation for the many concerns others have noted.

 

[texasfiremedic]

Penetration below grade and water tight seal. I have used these many times for wall penetrations that are below grade. Once they are tight they do not leak. Maybe this helps.

http://www.procoproducts.com/pensealbro.html
Here is their pdf
http://www.procoproducts.com/pdf/PenSealSinglesWeb.pdf

 

[eeprete]

Thanks for all the tips. Do these devices go on the outer portion of the block, the middle hollow area, or inside the basement?

 

[69gp]

inside the basement

 

[GS-Louie]

Having lived in a house with a block basement I would never do anything to penetrate the block wall below ground. I would go under the slab and then come up and go through the wall above ground. It is mush easier to do, easier to get a good seal and finish the penetration. Water will find a way in through any slight crack in the block wall.
Check the thread in this section about running TV phone and internet to a garage.

Good luck.

Lou