to cut or not to cut concrete control cuts

[jeffntanya]

ok well I've packed my gravel, layed my varpor barrior followed by 2" celfort 300 foam board.(btw I hate walking on this stuff.. always sounds like it's cracking. owens corning says it's normal). I'm in the process of laying my wire mesh followed by the kytec lines for the in floor heat. just about every concrete guy I spoke to .. inlucding the one that is going to pour/polish my floor says they don't like the idea of control cuts in a heated floor because of the risk of hitting the lines. but then they go on and tell me that if I don't the floor will definetly crack. floor area is going to be 30x40' with 5" of 32mpa concrete. when they pour they try to pull the wire mesh up 1" and I believe the kytec lines are 1/2" so this would make it approx 1 1/2" up from the bottom.. leaving approx 3 1/2".. how deep would the control cuts have to be? even if the guy pulls the mesh up 2" it still leaves 2 1/2" of concrete above the kytec... anyone have input on this one?

thanks,
Jeff

[DUNBAR]

That stuff has a class action lawsuit all over in Las Vegas Nevada where the oils of the product is leeching over the brass fittings and in turn dezincification is accelerated.

Zurn has a class action lawsuit too on their brass fittings breaking after a few years; made them too thin to help with flow problems and they are snapping under strain.

Whoops! and how many miles did you install of this stuff?

[HVAC HAWK]

yes you can cut the joints in the floor ,all you need to cut is 1" to 1 1/2 " deep . it will crack the est of the way .

[jeffntanya]

That stuff has a class action lawsuit all over in Las Vegas Nevada where the oils of the product is leeching over the brass fittings and in turn dezincification is accelerated.

Zurn has a class action lawsuit too on their brass fittings breaking after a few years; made them too thin to help with flow problems and they are snapping under strain.

Whoops! and how many miles did you install of this stuff?

are you talking about the kytec? I haven't installed it yet.. but it's being used all over around here. I thought it was made of copper and plastic?

[BHD]

It is harder but you can use a joint runner, or a jointer, it is either a hand tool or a tool on a pole that is use to make a control joint, and you make the first pass to push the rocks out of the way jsut after the first floating, and then make repeated passes as the floor is continues to set and the floor is finished, most use a screed board or 2x4 for a straight edge to make a straight line.

or you can pour it in ten wide foot pours, and then fill in between the pours on the second day removing the middle forms if you are really concerned about hitting any thing when cutting a control joint.

I think the control joint (depending on who is making the rules) is said to be 1/4 to 1/3 of the slab thickness,

but if it is a good 1/2" most of the time it is enough to guide the crack.
I have even had good results with jointers only 3/8" deep.

[PLUMBER RICK]

city of los angeles, dept of public works required me to cut 1'' deep for my driveway and approach, within 24 hours of the pour. so far so good. they don't allow mesh or rebar in the public right of way.

rick.

[drtyhands]

city of los angeles, dept of public works required me to cut 1'' deep for my driveway and approach, within 24 hours of the pour. so far so good. they don't allow mesh or rebar in the public right of way.

rick.
Earlier this summer our community watched a guy tear out his newly poured approach because he had put mesh in it,poor guy,good finish too.I guess they would rather have easy access to their property rather than let someone have a nice driveway:rolleyes:

So L.A. wanted you to pull a permit on your driveway so they could inspect it?

We do most of our driveways without the city here in the Ventura County.

[PLUMBER RICK]

Earlier this summer our community watched a guy tear out his newly poured approach because he had put mesh in it,poor guy,good finish too.I guess they would rather have easy access to their property rather than let someone have a nice driveway:rolleyes:

So L.A. wanted you to pull a permit on your driveway so they could inspect it?

We do most of our driveways without the city here in the Ventura County.


good catch adam:) long day and week.

the city inspected my approach and sidewalk. no mesh or rebar. permit required.

my driveway is 6'' thick, 1/2'' bar on 12'' centers. no permit required

big truck likes it this way:D

rick.

[drtyhands]

good catch adam:) long day and week.

the city inspected my approach and sidewalk. no mesh or rebar. permit required.

my driveway is 6'' thick, 1/2'' bar on 12'' centers. no permit required

big truck likes it this way:D

rick.

I know it has been a long week for You and Joey.

Goodnight Johnboy,Goodnight Mary Ellen

[Mr. Concrete]

ok well I've packed my gravel, layed my varpor barrior followed by 2" celfort 300 foam board.(btw I hate walking on this stuff.. always sounds like it's cracking. owens corning says it's normal). I'm in the process of laying my wire mesh followed by the kytec lines for the in floor heat. just about every concrete guy I spoke to .. inlucding the one that is going to pour/polish my floor says they don't like the idea of control cuts in a heated floor because of the risk of hitting the lines. but then they go on and tell me that if I don't the floor will definetly crack. floor area is going to be 30x40' with 5" of 32mpa concrete. when they pour they try to pull the wire mesh up 1" and I believe the kytec lines are 1/2" so this would make it approx 1 1/2" up from the bottom.. leaving approx 3 1/2".. how deep would the control cuts have to be? even if the guy pulls the mesh up 2" it still leaves 2 1/2" of concrete above the kytec... anyone have input on this one?

thanks,
Jeff

I poured one of these today. First, I take it that this is an indoor slab. If it is, then yes your concrete guy is right, in a way. Indoor floors are saw cut after the floor is ready to walk on, within a 24 hour period. Outdoor concrete most of the time is hand tooled/cut with a hand jointer. With a heated floor, you take a big risk of cutting the lines and I wouldnt saw cut either.
You can however tool in the cuts/joints with a hand jointer. they have different size depths/widths. Tell him to use a shallow #314 jointer (it will be a different # but the width will be the same), he will know what Im talking about.

As far as cracking, your concrete is going to crack, maybe sooner, maybe later. What the joints are for is to make the concrete crack inside to joints (thats why they are called controll joints) by making a week point in the concrete. Do you want control joints or not, the question should be do you want the cracks to be random in the floor or do you want the cracks to be hidden in the joints?

BTW, it sounds like the contractor is using the mesh for both placement of the lines and reinforcement of the concrete. With the expence of a heated floor, you should leave the mesh alone and use it to place the lines, but you should spend the extra .50 cents a sq ft and use rebar on top of the lines for the reinforcement of the concrete.