ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

Topic Options
Rate This Topic
#154059 - 02/20/04 08:02 PM Trenching Concrete Floors
Joey D Offline
Member
Registered: 10/10/03
Posts: 259
Loc: Arlington MA U.S.
I am on a job in a apartment building where the floors are all concrete. The contractor is framming a few areas in he middle of the ceiling to install recesed lights in. He has cut a 2inch deep trench in the ceiling from one lowered ceiling to the new one. The floors are only 8" deep. Would this be a smart thing to do?
Top
Building Codes & Related References
#154060 - 02/20/04 09:09 PM Re: Trenching Concrete Floors
crash Offline
Member
Registered: 10/21/03
Posts: 147
Loc: Calgary Canada
The only person who could answer that question is the Engineer who designed the building. If the engineer gave the contractor the go-ahead for this trench and the corresponding repair, then it should be okay.
Top
#154061 - 02/21/04 02:36 AM Re: Trenching Concrete Floors
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
I agree with Crash.

Any chance these are precast cement decks?

If yes as long as the pre-stressed cables inside are not cut it seems you can do a lot to them, with an engineers OK.

Without an engineers OK this sounds dangerous.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
Top
#154062 - 02/21/04 07:05 AM Re: Trenching Concrete Floors
Roger Offline
Member
Registered: 05/18/02
Posts: 1716
Loc: N.C.
I agree with Crash and Iwire. A structural engineer would need to be involved, and it would seem to me that there would be some specific instructions to the cutting.

Roger
Top
#154063 - 02/21/04 07:54 AM Re: Trenching Concrete Floors
DougW Offline
Member
Registered: 06/08/03
Posts: 1143
Loc: North Chicago, IL
I was going to ask if they were Spancrete, or another type of cellular concrete. Taking 2" out of that could be, uh, problematic.

Get a Structural Engineer's opinion.
Top
#154064 - 02/21/04 09:20 AM Re: Trenching Concrete Floors
u2slow Offline
Member
Registered: 09/18/03
Posts: 200
Loc: Salt Spring, BC, Canada
I work in mainly new highrise construction. Typical floors are 190mm (approx 7-1/2") and having to chip a shallow trench in the ceiling or floor (to bury BX cable or 1/2" ENT) has not been an issue with the engineers or inspectors so long as the steel isn't cut. Usually we don't have to go deeper than 1" or so, unless there's a spot where the rebar is too shallow and we have to go behind it.

Check with YOUR engineer first though

[This message has been edited by u2slow (edited 02-21-2004).]
Top
#154065 - 02/21/04 04:31 PM Re: Trenching Concrete Floors
Joey D Offline
Member
Registered: 10/10/03
Posts: 259
Loc: Arlington MA U.S.
Thanks. I was thinking the same.
Top

Member Spotlight
Member Since: 02/23/13
Posts: 204
New in the Gallery:
SE cable question
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box


Who's Online
2 registered (Admin, sparkyinak), 74 Guests and 9 Spiders online.
Key: Admin, Global Mod, Mod
 
New in the Gallery:
SE cable question
 
Top Posters (30 Days)
Admin 49
HotLine1 43
gfretwell 18
Ruben Rocha 12
Trumpy 9
 
Newest Members
Freecrowder, clee512, Jdscott2005, FAIZAN, Regitest2

ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals