Browse Forums Paving & Concreting 1 Dec 08, 2008 9:34 pm After many months of fighting the local council, my plans finally got approved. A few months ago the building process finally started.
Foundation was dug, slab was poured, frames have gone up and now the bricks 1/2 done. Everything was progressing well. That is until I had a closer inspection of the concrete slab over the weekend. I noticed many hairline cracks all over the slab from kitchen living area to the garage. Now this was only poured late September. I'm obviously not very happy about this, the SS is going to come out and take a look this week but I'm worried that he's just gonna tell me what I want to hear, i.e. everything is normal when it clearly isn't. Also worried that contractors might have used poorer grade materials and eventually lead to problems further on. Anyone had this problem before? Should I get an independent engineer/surveyor? I'm a bit stressed out now. Re: Cracked concrete slab 2Dec 08, 2008 10:00 pm Hi Fho
I have to preface my comments with the fact that I have no special expertise in this area. I doubt if your cracks are anything more than shrinkage cracks. These are of cosmetic significance only. By all means get expert opinion, but, in the meantime you might want to put a straightedge and very fine ruler over them. Shrinkage cracks are generally less than 1mm wide and the concrete on either side is perfectly flat...ie a straightedge sits flat on both sides without humps or gaps. I really wanted to avoid cracks in our slab, but it was poured on a clear, sunny 30 degree day that led into a cool evening and cold night. the curing compound went on about 2 hours after the slab was completed (immediately would've been ideal). Anyway, I knew cracks were inevitable and sure enough we've got some that look a bit like yours. (though it is hard to tell from photos how wide they are). It's funny how you stop noticing them when thay get covered with sawdust during the framing stage Cheers zeke FWIW, I once had an investment property that had some very ugly cracks in the double garage floor. Expert opinion assured me they were only shrinkage, but I seem to remember they were much wider than 1mm. Anyway, some caulking compound and an hour of my time produced a superb cosmetic result. They almost literally disappeared. I guess it's not an issue when floors will be covered, but I'd love to try a bit of flexible caulk on our slab. The builders would probably think I was nuts though, so I'll resist the temptation Re: Cracked concrete slab 3Dec 09, 2008 9:48 am Hey dont worry your cracks are normal, and you dont need to be worried.
If you can put your fingernail inside the crack then i would start to be worried. The reason why we have steel mesh in concrete is to stop cracks opening up when cracks appear. Concrete is strong in compression and weak in tensile strength. However steel is the reverse. So you should find the steel is doing its job. If cracks start opening up the issue is more likely to be that the concretor hasnt used the correct steel, or hasnt lifted it up high enough. before pour. Re: Cracked concrete slab 5Jan 04, 2009 7:01 pm I moved into my newly built home only six months ago, we had the same craks you talk about these are nothing to worried about very normal we had been told by my cousins who is a builder you only need to worry if the cracks open up Plumbers 'can be' plumbers, made all the worse by self certification which the building surveyor invariably accepts as proof of compliance! The good thing is that you know know. 3 4859 DIY, Home Maintenance & Repair Hi there, I just recently received my new house from my builder. We handed the house to another company to deal with the… 0 8910 The concreter will take and reuse. In my case I bought structural LVLs and scraped them back and used them as joists. 1 5152 |