Adjusting floor box height

[mstrlucky74]

What would you do if you had a 9" poured concrete slab and wanted to use this box? The leveling feet/screws on the sides of the box I don't think would give you enough height to make the top of the box flush with the top of the slab? What if the poured slab was even thicker? How would you mount box so the top would be flush with top of slab? Thanks


http://ecatalog.hubbell-wiring.com/productinformation/specsheets/3A/Live/PDF/CFB10G55R_cart.pdf

 

[cadpoint]

Use 5" 1/4-20 screws with nuts, I'd run a longer rod and send it right through to the metal deck,
and adjust accordingly.

You need to be upfront with the rod buster and surveyor (if on site).
Find out what's going in floor and have the surveyor check your spot elevation when your ready.
The buster should add additional rod framing around your opening.

Re-tape and cone or build a built up wood cover after the pour.
It could sit for a while exposed and alone...
Someone always seems to find a room for their stuff, just protect yours

 

[mstrlucky74]

thanks. do you mean longer screws in place of the ones on the box? someone told me there is are brackets used to raise the box up a few inches ive never heard of that.

 

[Strathead]

What would you do if you had a 9" poured concrete slab and wanted to use this box? The leveling feet/screws on the sides of the box I don't think would give you enough height to make the top of the box flush with the top of the slab? What if the poured slab was even thicker? How would you mount box so the top would be flush with top of slab? Thanks


http://ecatalog.hubbell-wiring.com/productinformation/specsheets/3A/Live/PDF/CFB10G55R_cart.pdf

I am assuming this is at ground level. Perhaps I am a hack, but I would just get a masonry block and dig a little deeper. then just mount the box leveled at the correct height on top of the block tying everything down really well so the concrete guys can't knock it around.

 

[mstrlucky74]

I am assuming this is at ground level. Perhaps I am a hack, but I would just get a masonry block and dig a little deeper. then just mount the box leveled at the correct height on top of the block tying everything down really well so the concrete guys can't knock it around.

huh? it's going on a poured concrete deck. not slab on grade.

 

[mstrlucky74]

Guess there could be different scenarios depending on the poured deck and I'm not exactly sure what materials/forms are involved in all poured decks, such as metal decking etc. but how are these floor boxes secured in place so they don't move? Thanks

 

[Dennis Alwon]

Jude gave a good idea .. Run threaded rod thru the decking and into the box. Adjust with nuts... I would probaly get a transit in there to get it right.

We had a similar job.... The floor outlet plate did not extend over the edges of the box-- it fit inside the box so we had to be right on. I think there was only an 1/8" play and we had 40 of them in a house-- what a nightmare

 

[Strathead]

huh? it's going on a poured concrete deck. not slab on grade.

In that case why wouldn't it be "floating" period? I would assume you need to work with the concrete person. He needs to provide you with a rebar platform that you can set the box on at the right height, or shim it up or put channel underneath, or tie a couple pieces of EMT or any of thousands of other methods, to secure it in place until the pour it done. On a floating deck they will need to have concrete under the floor box as well as around it. If it is on a metal pan, which 8" thick leads me to believe it isn't, then just replace the screws with threaded rod, or some screws from toggle bolts or any longer threaded thing that is the same pitch. But you will still need to rig something to hold it still. Concrete guys are very good at knocking things around. You really just have to wait until the work is getting done, and meet with the concrete guys. You could always try to talk them in to a Carlon E976RFB much easier as you can cut it off after the pour.

 

[cadpoint]

You have to go and study all of the various drawings and the complete cut list of this product.
Determine the exact size of metal deck.

Nine inch thick floors is usually 3” or 4” composite decking with the remainder being the concrete.
Your product might not fit even if 3” MD. It could require a change order and not the first time something was spec'd wrong.

The deck could be any thickness from 10 to 22 gauge. The gauge size will be a deduct in you calculation to align your box. IE a floor thickness is measured from the bottom of metal deck or where the MD touches structure through to the desired depth of pour.
I'm getting to excited, the top of a hat is the total distance, so measure of the top of hat of the composite deck to set top of box.

Gauge Chart

Depending on the size and type of MD used you could have re-bar you might have iron mesh mating, and also in combination with metal studs on the pour side of the metal decking. Metal stud are usually used with the deeper concrete pours.

Diagram of metal composite deck.

It should not be that hard to firm this box within the floor framing, as said earlier you could brace the underside with low profile kenduff/unistrut using the vertical supports and extend out to touch another hat of the MD, hat is the top part and the flute in the bottom or lowest point of MD.

Keep the last five or ten foot approach of piping free of strapping till you tie in the box. Set box then work in pipe, hopefully attachments from one side or connected side. If a TV/CPU interface Floor box they have lots of pipes. Use 1/2” EMT on top of MD hats or other support materials to align you pipes into box.

Tighten everything up coming to box, get and set elevation, transit it, check all connection and shoot it again. Some surveyor will shot a level shot or bench mark that you can reference off of, with your own level or even apply a string too.

You need to do this work, setting the box, (IMO) a few days before a pour, you don't want it to be a trip hazard or a burden to the other trades. Announce at production meeting that you need input from GC, chief rod buster, surveyor (if available) that your ready when they are to work out the details.

Time consuming yes, but fun and different to work with, hope this helps
Enjoy...

 

[mgookin]

Is your poured deck cold formed reinforcement or post tension?