Browse Forums Building A New House 1 Aug 17, 2009 9:11 pm Hi guys We had the slab poured today, and while measuring the concretors picked up a mistake in the footings. The footings on one side (around 4m in length) are around 200 - 300mm too short. The concretors have extended the final floor level by 200mm-300mm and have also added some extra reinforcement but should we be worried about this? The footings are 700mm deep and the final floor level is 300mm. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Footings too short? Should we be worried? 2Aug 17, 2009 9:39 pm Its good that you have Photos, There should be an engineer involved who would have done the design for the slab. I imagine that he will need to sign off on what the concreter has done. I would tell the builder that you want his approval of the change that was done on the fly and how the extension was done to the slab and that it has not changed the certification of the slab. Dan C Re: Footings too short? Should we be worried? 3Aug 17, 2009 9:42 pm ^ she is an owner builder, so should she go to the engineer for clarification? Custom European Cabinets - Melbourne Kitchen Specialist PM for business details as website currently being updated! Our Crazy Owner Builder Journey! Re: Footings too short? Should we be worried? 4Aug 17, 2009 9:53 pm What is the rest of the structure? Timber?? onc_artisan Where you are coming from is where you are going to... Re: Footings too short? Should we be worried? 6Aug 17, 2009 9:57 pm The engineer checked the footings and reinforcement steel on saturday and said that everything was fine. He will provide us with a certificate for this. Mind you, he didn't take out the tape measurer or measured anything Luckily, the contractors measured and picked up the mistake today. We were planning to let the footings guy (who also organised the concretors) that we want it fixed as we are not happy with it. Just not sure if we are overreacting... It will be steel frame/ brick veneer. Re: Footings too short? Should we be worried? 7Aug 17, 2009 9:59 pm borg Hi Getting there. I am not confident that the reinforcement(steel) they have placed is sufficient. As is doesnt really overlap the existing rio steel where it perhaps it should have. Yes, that's what we are worried about also. Not sure if it makes any difference, but it is a two storey house so the load will be even greater than it normally would... How would they go about fixing this? Wait till the slab dries and digg out under and fill with extra concrete? Re: Footings too short? Should we be worried? 9Aug 17, 2009 10:03 pm gettingThere borg Hi Getting there. I am not confident that the reinforcement(steel) they have placed is sufficient. As is doesnt really overlap the existing rio steel where it perhaps it should have. Yes, that's what we are worried about also. Not sure if it makes any difference, but it is a two storey house so the load will be even greater than it normally would... How would they go about fixing this? Wait till the slab dries and digg out under and fill with extra concrete? this is not my area of expertise however i wonder if someone else can comment on the possbility of drilling 12 to 16mm bore holes around 500mm long and banging steel rods through the slab. Is this pyhsically possible. THis will prevent the slab breaking off on the end. Also was the trench dug out to natural ground on the extension?? Re: Footings too short? Should we be worried? 10Aug 18, 2009 9:29 am You can't bang steel rods through the slab to the same effect as getting it right in the pour. if the concreter was worth his salt he would have put properly supported steel rods in before the pour and had a good overlap of at least 500 mm. The supports would ensure good coverage of concrete. The Mesh should also have had an overlap, maybe 400mm. I note also that the steel that he used was pretty rusty and thats not usually a good thing, but as long as it wasn't flaking off. in the end the concrete needs to bite onto good steel. What comes into play is the ground that it is sitting on, if it is solid rock or clay subject to expansion and contraction will determine how hard the slab is pushed from below. If it is a solid base then there shouldn't be a major problem, if it is highly reliant on the beams to bridge or withstand a lot of movement you may get a crack there depending on how well the steel was positioned. Remember steel is all about protecting the concrete from tensive forces not compressive. So bricks on the concrete edge are ok if the soil underneath doesn't move and the steel really only comes to play if it does. ie it starts to stretch the concrete say if it drops a little. Again show the photos to your engineer, get his opinion. engineers never run tape measures around the job they just check that all the underlyng requirements for concrete, piering and steel are met. Our engineering drawings are not exactly to scale and the job is highly reliant on the accuracy of the architect drawings. In our case we needed to correct dimension errors of 15 mm, our frames, built off site fit perfectly on our slab. I understand that you are an owner Builder, I would buy a tape measure and spend more time on site. In the end people make mistakes and the more people checking the better off you will be. The one thing in your favour with this error is that it was caught before the pour. Dan Re: Footings too short? Should we be worried? 11Aug 18, 2009 9:45 am I think it looks a bit *******...but surely the engineer would know, and if he is willing to sign off...but footings are there for a reason...and your brick wall won't be sitting on top of the footings...if the engineer reckons this is ok, why worry about footings anywhere...I wouldn't accept it...very ordinary. Re: Footings too short? Should we be worried? 12Aug 18, 2009 10:23 am getting there. just had a thought. Have you confirmed that the new footing is in fact in the correct possition? and that the orginal location was incorrect. The reason why i ask it that it is very comman for people to think they have made a mistake when a million things are happenign at once, where if fact it may have been right all a long. Might need to confirm this and if the new location is correct make sure that it is spot on and doesn tneed any further work, in relation to the sizing let alone the issues raised above. Re: Footings too short? Should we be worried? 13Aug 18, 2009 12:46 pm borg Hi Getting there. I am not confident that the reinforcement(steel) they have placed is sufficient. As is doesnt really overlap the existing rio steel where it perhaps it should have. That is what the engineer said when we showed him the photos He will measure the thickness of the top slab (where there is no footings) but he reckons if it is 300mm or thicker it should be ok :S Fingers crossed it works out ok. Re: Footings too short? Should we be worried? 14Aug 18, 2009 7:20 pm All sorted. Spoke to the engineer and the footings guy. The footings guy will dig out around and under the top slab bolt up some reinforcement rods into the existing slab and fill up with concrete. The engineer will come to check before he pours the concrete. YAY! It will be neat but you won't have much freeboard. At least they are not weep holes. Are you in a high intensity rainfall region? The regulatory slope is only required… 3 8394 Firstly, if your house is still under builder's warranty (10 years in Victoria) you should have no need to crawl into roof space but let the builder handle it, unless you… 3 5703 |