Sawcuts not installed by contractor 3

[gagne73]

I have a homeowner who is pretty worked up about sawcuts not installed in his slab-on grade for garage/driveway. He wants his homebuilder to re-do both slabs, which in my opinion is quite over teh top. is tehre any suggestions of how to possibly approach a recommendation?

really the only risk is that cracking wont be controlled, and wont have caulking over it to prevent infiltration when it does crack, which COULD lead to a bit shorter lifespan. Frankly every driveway cracks anyway, so I dont see an issue personally. However im not the one who paid 10 to 15k for the slabs. I understand the owners frustration, but there really isnt much that i can think to help. possibly wait for it to crack, then clean teh cracks, caulk them, and do a stamp/finish layer on top is all i can think of, but I dont like the finishes that are added after the fact.

can anyone provide a bit of insight on times where saw-cuts were missed, and what, if anything was done about it? this is about a 4", lightly reinforced slab-on-grade, Canadian climate.
Thanks everyone

 

[BridgeSmith]

Is there a reason why the sawcuts can't be made now? Concrete doesn't cut quite as easily after it's cured, but a concrete saw can still make the cuts.

 

[oldestguy]

Ideally the cut should be made early on of course, ideally even while you can't walk on it yet. So better now than never. One might go to what ever spec there was and ask for a refund of some amount to ease the mind of the owner. The clearer the spec or work order, the more to refund.

 

[atrizzy]

You could do it now, but chances are that some microcracks have already formed due to shrinkage and the crack control purpose of the sawcuts likely won't be as effective.

 

[oldestguy]

I once taught a graduate class with more work on subjects not covered well as undergrads. Part of the course on pavements involved a field trip to construction projects. Visiting the placement of concrete for a continuously reinforced pavement placed via slip forms moving along with the screed and rough finisher. Minutes after placement the edges of the fresh concrete showed the cracks forming about every 5 feet or so. They eventually showed up in the completed surface areas after setting. It starts right away.

 

[structuralsteelhead]

Better late than never. I would insist the contractor provide the sawcut service (32xT/12)max center to center at no cost and hope for the best. Long term shrinkage will still occur and if slab lightly reinforced, a sawcut may help. I've never used joint filler in a residential slab if this the case.

 

[CANPRO]

I’d leave it, you already missed the boat on the sawcuts (assuming this has been a few days). Yes there’s some shrinkage left long term, but the weak planes in the concrete have probably already formed, meaning you’d need significant sawcuts to make a weaker plane, which could do more harm than good. Sawcuts will be nothing but maintenance issue at this point.

I’d give the contractor two options: Rip it up and do it right, or hold back projected maintanence costs.

 

[dik]

Atrizzy... first correct answer. Time of sawcutting is critical. If not done 'on time' you may as wait until it cracks and route the cracks... the microcracking has already determined where the cracks will develop. Sawcutting after does nothing, and, you can often find shrinkage cracks formed a foot or so away from the sawcuts.

Dik

 

[Ron]

Sawcuts must be done the SAME day as placement. Variations in concrete thickness create random stress distributions that must be overcome quickly by the sawcuts. They must be done quickly and to proper depths....if you don't do that, then as dik and others said, wait for the cracks to show up (30 to 45 days will show them widely enough to properly route them), if you want to accept substandard construction.

Any contractor who places concrete without provisions for proper sawcutting is a contractor who knows little or nothing about concrete technology and has no business placing concrete.

When the cracks do occur, they might not be as closely spaced as proper control joints would be. That results in wider cracks over time. Wider cracks allow more water in, provide less load transfer and will ultimately lead to slab failures under many conditions.

The contractor did not provide an appropriate service. He should not be paid until he corrects the slab, which should be removed and replaced properly. Anything less is a compromise to the service life, aesthetics and maintenance of the slabs.

 

[dik]

I don't think the same day is good enough... should be done within 6 or so hours after finishing. This can be improved by using a sofcut type saw. Ron hit the nail on the head when he notes that sawcutting is part of the planning process... else you may be sawcutting at 2 AM.

Dik

 

[gagne73]

wow, thanks guys, I was not expecting that many responses that quick, and late in the day. In my haste of typing the original post, I should have clarified, this is an issue that has come up on the 1 year warranty walk through, so the slab is a year old. not much point in adding saw cuts now. My general recommendation was to simply fight for a bit of a cash reimbursement, however i doubt he would get the slab replaced, and i would not be able to ethically fight for him to get the slab replaced, as i don't really agree. frankly, slabs crack. thee are almost no driveways here that don't crack, regardless of sawcuts.
I then recommended he contact a local company who uses MG-Krete to do a top coat, but I'm not sure if existing cracks will propagate through again or not. He is talking about getting lawyers and stuff involved. i unfortunately for him, don't fully support his goal, so i don't think i can help him.

 

[dik]

Was the contractor notified at the time of occurance? Anything about sawcutting in the Specs? Likely a bit late to get some money back...

Dik

 

[oldestguy]

gagne73: Well, we all got a chance to dive in. Lessons here: have a detailed spec., enforce it at the time, and any post here should be as complete as possible first time.

 

[BridgeSmith]

Well, if it's a year later, it's cracked from shrinkage about as much as it's going to. Does it have severe or even noticeable cracking now? If not, then the homeowner really doesn't have anything to complain about. If there are noticeable cracks, then there could be a durability issue later on, especially if you're in a cold climate - freezing water and deicing salts will destroy the slab eventually. In that case, perhaps a compromise, in the form of a sealer or overlay, could be a satisfactory solution. For our bridge decks, we've used methyl methacrylate healer/sealer compounds for many years and they work well, even under the heavy traffic and deicing salts they are exposed to. If the homeowner's issue is how it looks, an epoxy overlay could be an acceptable solution.

 

[gagne73]

Thanks guys,
HotRod, my thoughts exactly. I have nto actually went to view teh slab yet, as I explained to him my opinion, and I think he realized that he was not going to have my full support in terms of recommending replacing.
dik - I wasnt actually involved in teh buid, i just got the phone call now at one year, as a "3rd party" observer. It seems that the missed sawcuts was not noticed at time of turnover for the house.
dik/oldest guy - definite lessons learned for the homebuilder, not sure if they will note it. therein lies the issue of not having a consultant oversight in homebuilding. once the builder gets the plans from the tech, the builder is basically in charge. Im not a huge fan of how the home building industry leans so heavily away from the homeowner.

thanks everyone

 

[Teguci]

Getting worked up about not having sawcuts after one year, ugh. Tell the contractor to put a new sawcut right next to each of the shrinkage cracks that have certainly shown up by now. At least then they can pretend to know what they are doing while they caulk and seal both the cut and crack in parallel. If you want a good control joint then pay to have the joints tooled. Sawn joints (even soff cut) are hard right angles that may get damaged under repetitive load (of course you don't detail those chamfers on concrete columns and beams either). A tooled joint profile is the professional way. Sawn cuts are the cheaper way and have become the standard.

 

[XR250]

A tooled joint profile is the professional way. Sawn cuts are the cheaper way and have become the standard.

Ironically, most tract homes I see use tooled joints in the exterior flatwork and garages. They seem to be quite effective.

 

[dik]

A tooled joint profile is the professional way. Sawn cuts are the cheaper way and have become the standard.

You have a helluva time using a Goldblatt groover the next day...

Dik