Browse Forums Paving & Concreting 1 Dec 30, 2012 5:30 pm Hi All, I moved into my house in Point Cook about 2 years ago. At the time of moving in, there were small hairline cracks throughout the house and garage. Site Supervisor says that this is normal as the house is "settling". As the flooring of the house has been covered by tiles and carpet, I cannot see the cracks anymore. However, the cracks in the concrete of the garage floor remains and is getting bigger over the past 2 years. Most of the cracks are about 1mm wide, few up to 2mm wide. The cracks in the garage are like a grid like pattern, like boxes, hence they are not random. There are no cracks in the garage ceiling or any cracks in the house ceciling or cornices. All the doors seem to close fine. Had a visual looks around the bricks external to the house, there are no cracks there as well. I had a Simonds site supervisor who came in and advised that 1mm is normal. So no action required from them. I'm hoping to know if my house is structurally safe? And secondly, what steps can I take to fix the issue? Any advice greatly appreciated! Thanks! I have taken a couple of shots of the garage floor and a video. See below. Youtube video Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Concrete Cracking Overtime - help! 3Dec 30, 2012 9:03 pm What size are the cracked areas ie 200mm x 200mm? Where you are coming from is where you are going to... Re: Concrete Cracking Overtime - help! 4Dec 30, 2012 10:01 pm Hi Kingster There are three probable causes of your concrete cracking 1 Understrength concrete (too much water added on site caused excessive shrinkage) 2 lack of curing 3 Inadequate or more likely incorrectly placed reinforcing You won't know unless you arrange concrete testing. I would not be jacking up your car in the garage or you might see the jack collapse through waffle pod Concrete appearance is part of it's functionality. If it does not look right it isn't. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Concrete Cracking Overtime - help! 5Dec 31, 2012 8:30 am building-expert Hi Kingster I would not be jacking up your car in the garage or you might see the jack collapse through waffle pod Hi BE. Can you give me an example of this happening - ie a link or pictures. Thanks. Re: Concrete Cracking Overtime - help! 6Dec 31, 2012 12:14 pm I haven't seen it myself but I heard it has happened to someone. http://somersoft.com/forums/showthread.php?t=21671 Waffle slab is only 85mm between stiffening beams With concrete cracked like that and the prospect of under strength concrete + possibility of poor workmanship I would not be taking any chances getting under a hoisted car. Just common sense Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Concrete Cracking Overtime - help! 7Dec 31, 2012 12:29 pm onc_artisan What size are the cracked areas ie 200mm x 200mm? There are line cracks all over the garage floor. They are like in a grid like pattern, not random. I measured the width of the crack up to 1mm, a few up to 2mm. Is that considered big? Re: Concrete Cracking Overtime - help! 8Dec 31, 2012 12:39 pm building-expert Hi Kingster There are three probable causes of your concrete cracking 1 Understrength concrete (too much water added on site caused excessive shrinkage) 2 lack of curing 3 Inadequate or more likely incorrectly placed reinforcing You won't know unless you arrange concrete testing. I would not be jacking up your car in the garage or you might see the jack collapse through waffle pod Concrete appearance is part of it's functionality. If it does not look right it isn't. Thanks building-expert. You are certainly very knowledgeable in this area. What kind of companies will be able to do concrete testing? Do you have any you can recommend? and how much do they usually cost? What does "jacking up your car in the garage" mean? As in parking the car in the garage? Thanks. Re: Concrete Cracking Overtime - help! 9Dec 31, 2012 12:56 pm It means using the car jack "lifting device" to raise the car for the purpose of changing a flat tyre. The concentrated load from car weight over a small area can cause local failure "a hole can be punched through the concrete" If you happen to be under the car when it happens it would most likely be fatal I would not be getting under any car lifted from waffle pod whether it looks cracked or not. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Concrete Cracking Overtime - help! 10Dec 31, 2012 2:40 pm kingster onc_artisan What size are the cracked areas ie 200mm x 200mm? There are line cracks all over the garage floor. They are like in a grid like pattern, not random. I measured the width of the crack up to 1mm, a few up to 2mm. Is that considered big? I think he wasn't talking about the actually crack width (1-2mm) more like the spacing from each crack across to another set of cracks. Re: Concrete Cracking Overtime - help! 11Dec 31, 2012 2:56 pm building-expert I haven't seen it myself but I heard it has happened to someone. http://somersoft.com/forums/showthread.php?t=21671 Mmm, I've heard the story before but never met the person it happened to. Only ever heard it was a friend of a friend. I have heard it from builders who don't use this method ... It has been passed by all authorities and rule makers. And, no - we don't have one so I'm not trying to rationalise ... But, I have a friend who has one and claims that in a recent earthquake in Victoria his slab remained intact while the older style slabs cracked in some houses. They also have other advantages - eg insulation. I'd say if the cement is poured to the correct specifications it should be just as good as a conventional slab. A bit like the fibre-glass pool that popped out of the ground - while full of water ! Re: Concrete Cracking Overtime - help! 12Dec 31, 2012 4:14 pm No Problem Saint Mike Would you like to jack up 4 wheel drive over one of those cracks then crawl under the car for servicing or repairs? I think you have too much trust in authorities and rule makers and in probability of pouring to correct specification. I would rather rely on my common sense. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Concrete Cracking Overtime - help! 13Dec 31, 2012 5:24 pm building-expert No Problem Saint Mike Would you like to jack up 4 wheel drive over one of those cracks then crawl under the car for servicing or repairs? ........ I would rather rely on my common sense. Just to go off-topic a wee bit..... But common sense tells me to NEVER work under any car being held up just by a jack. And yes I do know of someone who was crushed because a jack failed. And he was a mechanic by trade. Re: Concrete Cracking Overtime - help! 15Dec 31, 2012 8:40 pm Yep - I'm wary of getting under a car with a jack as the main support. I'll change a tyre. But, was this slab a waffle pod ? I missed that. Re: Concrete Cracking Overtime - help! 16Jan 01, 2013 8:32 am Just educated guess Two year old Simond home in Point Cook. What are the chances it's not Waffle? kingster can correct me if I am not right. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Concrete Cracking Overtime - help! 17Jan 01, 2013 4:05 pm I'll take your word for it ... I'm already learning too many things on building ... Re: Concrete Cracking Overtime - help! 18Jan 01, 2013 6:15 pm Looks like it could be inadequate reinforcing. Some unscrupulous grano workers cut corners on this or concrete mix cos it's most expensive part of job...I'd be getting a second opinion. Re: Concrete Cracking Overtime - help! 19Jan 02, 2013 3:10 pm If I was guessing I would say that the most likely cause is reinforcing mesh sitting on bottom or close to the pods and that it was not chaired up to sit at proper level. Slabs are frequently passed before all preparation is complete and this could have been missed. Core test would determine strength of concrete and the location of reo. Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Concrete Cracking Overtime - help! 20Jan 03, 2013 12:43 am Treeseachanger Looks like it could be inadequate reinforcing. Some unscrupulous grano workers cut corners on this or concrete mix cos it's most expensive part of job...I'd be getting a second opinion. ??? concrete without mesh cracks randomly not in grid formation... wet concrete 'crazes' like i saw in one of the photos. Mesh on the bottom ie 100mm down won't 'mirror' on the surface, but will affect the bottom. mesh on the bottom 1/3rd aposed to the top 1/3 will offer different kinds of flexural modulus, mesh that was lifted and NOT sitting on a chairs can sometimes 'float'. Wet concrete poured on a hot day will craze like drought affected clay or soil. 'Snapped' concrete with an attempt at 'finishing' with a volume of water will affect the longevity of service. FWIW Where you are coming from is where you are going to... 1 6629 Yes, unless you are in a low intensity rainfall area or the area is protected from rain. Do you have access to NCC Part 2 or can you download it? I can email you a copy… 10 12511 |