4" Core through floors

[Alwayslearningelec]

If you had (6) 4" conduits gopgin through existing floors and they had to be cored would you individually core or creatwe a slot for all them. Seems like individual cores would be MUCh more time consuming

 

[gadfly56]

If you had (6) 4" conduits gopgin through existing floors and they had to be cored would you individually core or creatwe a slot for all them. Seems like individual cores would be MUCh more time consuming

Time to talk to the structural engineer. In fact, if this is new construction you are usually required by the specs to consult the structural engineer before making any penetrations not already on the drawings.

I know that you might be able to cut (6) 4" holes more readily than a slot depending how far apart they are because a slot is more likey to interupt more of the rebar than separate cores. And with that, we've pretty much exhausted my knowledge of reinforced concrete slab construction.

 

[Rewire]

coring will make firestopping easier

 

[480sparky]

coring will make firestopping easier

My first thought.:roll:

 

[Alwayslearningelec]

Time to talk to the structural engineer. In fact, if this is new construction you are usually required by the specs to consult the structural engineer before making any penetrations not already on the drawings.

I know that you might be able to cut (6) 4" holes more readily than a slot depending how far apart they are because a slot is more likey to interupt more of the rebar than separate cores. And with that, we've pretty much exhausted my knowledge of reinforced concrete slab construction.

Good stuff, thanks.. it is a renovation....but good insight about the integrity of the slab.

 

[iwire]

coring will make firestopping easier

Big time.

 

[Alwayslearningelec]

Big time.

\

Exactly why though? Thanks.

 

[480sparky]

\

Exactly why though? Thanks.

If your pipes are, say, 4?" OD, you drill 5" holes, and you end up with only a ?" space all the way around each pipe.

Cut out a big rectangle, and you've got two 'triangular' spaces between each pipe big enough to park a Volkswagen in that you need to fill with some sort of firestop.

 

[iwire]

Cut out a big rectangle, and you've got two 'triangular' spaces between each pipe big enough to park a Volkswagen in that you need to fill with some sort of firestop.

And fire stop is not cheap.

 

[gadfly56]

And fire stop is not cheap.

And fire stop material may not be enough. Such a floor is likely to be fire-rated, as you and others have inferred by your comments. You will need to install a "fire-rated assembly", not just stuff the crack with some 3M FD-150+. You'd have to look at the application brochure which would tell you to see UL System C-AJ-1317 and install per those requirements. But I agree, a slot is likely to be much tougher to protect than a single circular penetration.

 

[hurk27]

If you had (6) 4" conduits gopgin through existing floors and they had to be cored would you individually core or creatwe a slot for all them. Seems like individual cores would be MUCh more time consuming

Make sure this floor is not a pre-stress type, if it is, your going to need a metal locater, which you might need anyway to keep from hitting other pipe or re-bar, you do not wana hit a pre-stress cable.

 

[satcom]

Make sure this floor is not a pre-stress type, if it is, your going to need a metal locater, which you might need anyway to keep from hitting other pipe or re-bar, you do not wana hit a pre-stress cable.

Other things to watch for when cutting any floors are changes live load factors, sounds like something you engineer should be tending to.

 

[MikeyinLA]

Saw a plumber core through (8) number 11 re-bars, twice, man that cost him about $50K...

Be sure before you drill/core/dig/cut.
Structural engineers are expensive, as are lawyers :roll:

 

[LarryFine]

... you do not wana hit a pre-stress cable.

Back when I was a helper, I was told (by a boss who apparently didn't know (or care)) to cut through a post-tensioned cable in a floor with a cold chisel and a baby sledge.

I never heard of any repercussions about it, but you sure can hear the boom throughout the building.

 

[gadfly56]

Back when I was a helper, I was told (by a boss who apparently didn't know (or care)) to cut through a post-tensioned cable in a floor with a cold chisel and a baby sledge.

I never heard of any repercussions about it, but you sure can hear the boom throughout the building.

How far apart did the cable ends wind up?

 

[Alwayslearningelec]

Make sure this floor is not a pre-stress type, if it is, your going to need a metal locater, which you might need anyway to keep from hitting other pipe or re-bar, you do not wana hit a pre-stress cable.

Is that post tensioning??? THanks.

 

[MikeyinLA]

Is that post tensioning??? THanks.

Post-Tensioned Concrete
Buildings Home > Post-Tensioned Concrete

Stressed anchorage Designers use post-tensioning as a way to reinforce concrete by prestressing it. In prestressed members, compressive stresses are introduced into the concrete to reduce tensile stresses resulting from applied loads including the self weight of the member (dead load).

More....... >> http://www.cement.org/buildings/post_tensioned_splash.asp



The tension on the cable is incredible, I was stunned the first time I saw just how much tension was applied to the cable.

 

[LEO2854]

Post-Tensioned Concrete
Buildings Home > Post-Tensioned Concrete

Stressed anchorage Designers use post-tensioning as a way to reinforce concrete by prestressing it. In prestressed members, compressive stresses are introduced into the concrete to reduce tensile stresses resulting from applied loads including the self weight of the member (dead load).

More....... >> http://www.cement.org/buildings/post_tensioned_splash.asp



The tension on the cable is incredible, I was stunned the first time I saw just how much tension was applied to the cable.

good link thanks.hers one for fire stop.
http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSu7zK1fslxtU4Y_1mY_Bev7qe17zHvTSevTSeSSSSSS--

 

[infinity]

Seems like individual cores would be MUCh more time consuming

Chopping a slot in a slab that may contain rebar is not fun and IMO core drilling would be easier and faster.

 

[jumper]

I agree with the others: drill.