is this something wonky with newly installed conrete floor ?

[robb]

So my GC/Builder poured our basement floor and garage floor.

So i asked about cutting one crack relief groove between a smallish 8 x 10 extension tongue off main garage floor for a shop/storage area.

I figured that 8x10 tongue would eventually be source of a crack so I wanted to control where crack would go ... so cut a crack guide groove .

1st - is that sound logic ?

2nd - Is this next part WONKY ?

I go to check out the progress and i find that alot more grooves than i asked for have been cut ??

There a big cross ( + ) cut on the main garage floor

There is a huge lattice # (or two big connected crosses ++) cut into the basement floor ? didn't ask for any of those so i guess the GC/builder took it upon themselves to do.

Is that wonky, good, bad, useless etc, ideas , thoughts and experiences welcomed ???

Thanks, robb

--- news://freenews.netfront.net/ - complaints: [e-mail] ---

[trader_4]

Yes, IDK how many feet apart they are supposed to be, but they are important so that the concrete can move at the control joint, instead of cracking randomly.

You definitely want them to break up large spans. I'd say about every 10ft or so, from what I see around here. I have a stamped concrete patio, where they cut control joints, but only to break up the long side. The shorter side, which is still probably ~15ft, they didn't cut in that direction.

15 years later, it's cracked, the run in the other direction with the cuts every 10 ft or so, is fine.

[robb]

good, avoiding random cracking was the hope/ idea....

In know GC/builder should know more than what than the average lot .... BUT, that is my baby and no one will love your baby like yourself would,

AND I am finding busy GC/Builders seem to be in constant cost trimming mode.... if they think something is good idea or better but not necessary they will lean toward the time saving and cost saving decision.

good again, the lines are probably at the 10 - 12 ft apart like you suggest.

garage (with + in center) is 20 x 22 and the basement floor (with # cuts) has a continuous run 50' one direction and a 30 ' section the other way.

thanks for help . i've never seen a basement floor cut like that so i thought it seemed unusual and wonky especially since i did not ask for it and it definitely cost something.

thanks for help, robb

--- news://freenews.netfront.net/ - complaints: [e-mail] ---

[dpb]

On 12/19/2014 9:35 AM, robb wrote: ...

...

Generally basements slabs are left smooth as a (did I say general :) ) rule as the hairline cracking isn't normally much of an issue given lack of real loading such as the garage slab. Can't hurt but depending on whether there's to be floor covering or not, may have to fill or do something else to prevent show-thru for that. All depends on what's going to happen to it in the end...

For the garage slab oftentimes they'll not there either, but it's _a_good_thing_ (tm) there to help avoid larger movement later as the higher expected point loads from the vehicles raise far more concentrated stress patterns.

In the house I bought (speculation-built, not custom), they didn't adequately pack the fill under the basement slab as it was built on a hillside w/ the garage entry door on the uphill side and the whole slab settled as much as 8" tilted to the back side and was still some 6" air gap under it. Had to shore up the rear supporting wall and use the pressure-injection fill to bring it back up eventually. Fortunately, they poured a thick-enough slab it didn't crack up terribly bad but did have some pretty good breaks. In the end after a brush-in of dry cement after patching the larger it didn't look half bad when we sold the place. I saw it just two years ago on a visit and it's still about as was then. Point is, cosmetic cracking is just that and isn't too much to be concerned over.

[robb]

On 12/19/2014 9:35 AM, robb wrote: ...

...

Thanks for info and experience.

I mainly wanted to be pre-emptive with high probability cracks, like the concrete 8x10 tongue and make the crack go to a groove.

on the garage floor they had already dug-out space for three concrete beams (with 3 rebar in place) under the garage floor with one at the tongue and two at even intervals running laterally across the floor and with a footing around the perimeter. Seemed like it would be plenty strong and i am pretty sure they were on undisturbed dirt except for 3-4 feet of backfill along the basement walls where the garage floor connected to the top of basement wall

The basement had concrete footing beams under all the load bearing spots of the floor. But it was quite a long run of concrete floor along the back so i can see how that would be a preventative measure. But i don't think GC was going to do it until i mentioned cutting for the garage floor.

Don't want to make a big deal with GC/builder, they did more than expected and if it was something good then i certainly will appreciate it.

I didn't know enough to know if that was good or just useless (but appeared lavish / altruistic / responsive) .

thanks again for helpful comments

robb

--- news://freenews.netfront.net/ - complaints: [e-mail] ---

[hrhofmann]

Sounds like this GC is a keeper.

[philoÂÂ]

Huge lattice is probably good. I certainly have seen random cracking where only a very shallow groove has been scored.