Browse Forums Paving & Concreting 1 Feb 06, 2011 2:48 pm I recently had a handyman (well known franchise) lay a concrete slab for us and erect a shed. He built up the earth a foot on one end to level the slab and shortly after poured. The built up end didn't come out any further than the edge of the slab and now a few months later the soil has washed away (or packed down maybe) and the slab is undermined at one end. Should I be asking him to come and do something about it? I'm afraid the slab might crack. So far he hasn't answered my emails. Any opinions would be appreciated. Re: Soil under slab washing away 2Feb 06, 2011 5:27 pm I would definitely complain. For the area built up, if it was compacted fill, should have been sloped back at a slope of around 1 in 2 to the original level the only time a steeper slope should be used is if the fill was stabilised sand ( thats sand with 5% cement) The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Soil under slab washing away 3Feb 07, 2011 12:47 pm For starters, any soil/sand/other material used to "build up" an area to have concrete should be properly compacted. Look at housing slabs for instance, they often have sites where fill is required, but there are specified measurements for the fill to taper off, suitable drainage has to arranged. I know of a couple of people who were told to either pave or concrete around the base of the house to stop the fill washing away. If there was even a chance that water would run around the footings/slab of the shed then you should have installed adequate drainage to direct the water elsewhere. Did you pay the handyman to lay a slab or to prepare the site for a shed including all drainage and other requirements? Re: Soil under slab washing away 5Feb 09, 2011 8:19 pm Somehow I don't think this guy is going to answer my emails. I'm wondering what the best way to fix this situation will be - just to pile up dirt around it or would there be a better way? Once again any suggestions gratefully received. Re: Soil under slab washing away 6Feb 09, 2011 8:22 pm you will need to box it up and fill it 'A bottle of wine contains more philosophy than all the books in the world.' Louis Pasteur Vegie garden: viewtopic.php?f=19&t=27637&start=0 My Backyard Adventure Re: Soil under slab washing away 7Feb 09, 2011 9:09 pm Jassy How big a shed? What soild type? What was the total cost? Did you get a permit? Normally a shed floor is 100mm think, in most cases. It should have piers under the load bearing sides. The soil is washed away you said. So what washed it? Rain. Have you got spouting on it yet? When you have wash out or possible voids under the slab there is not much you can do, just dig down and fill the side in with concrette. Did you get a receipt from them any warrany? Sorry to say it but this is not uncommon, yet can be avoided by good site prep and drainage/run off. You must have soild ground and water run off to avoid this & other slab problems. Hope all goes well. KW.......... “It's just as unpleasant to get more than you bargain for as to get less” George Bernard Shaw. Re: Soil under slab washing away 8Feb 10, 2011 1:56 pm Another * job. Should have been compacted and have made allowances for drainage. Even if compacted often common to bore some piers in the fill. Complain to head office of franchise they should be more concerned. To fix you need to support the slab and fill is unlikely to achieve this as its difficult to get underslab and compact. Good luck. The franchise will take an interest, and or the department of fair trading. Pulpo Re: Soil under slab washing away 9Feb 10, 2011 4:35 pm Thanks to you all. It's not a very big shed - just one of those 3 metre square corrugated affairs sold by Bunnings as garden sheds. The soil is clay. I hate making complaints but I probably should let the franchise know that this bloke won't answer emails when something goes wrong with his work. I stll will need to fix it however, and it sounds like the best way is with more concrete. Would that be right? Re: Soil under slab washing away 10Jun 01, 2011 11:51 am No more news on this? This slab was not designed properly (obviously). But, we had numerous "professionals" coming over and suggesting basically the same! Generally speaking, is concrete really the only way to fill the voids under slabs? Better yet, is it really necessary to fill the voids at all (if you have piers)? I heard that it's not needed. My signature is distracting people from my wise posts ... Re: Soil under slab washing away 11Jun 01, 2011 5:40 pm Yes you need to fill under slabs. The majority of ground slabs are not fully structural designed to span across voids. Concrete or cement grout is best as it flows. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Soil under slab washing away 12Jun 01, 2011 6:17 pm Ended up speaking to some structural engineers (and this is in relation to my other thread). Some are cautious and suggest the builder to inspect and give us their assurance in writing. Some are saying that edge beams /slabs are capable of (and do) bridge from pier to pier and that no action is required and that it's the piers that take the load (and transfer it down). Worst case, we could pack some sand (or quick set cement ) under the slab to prevent rodents, snakes and the like to settling in. Don't know what to think! I thought that slab on ground should be relying on the .. well, ground, for support, and not on piers. Turns out that our waffle slab on ground is sort of suspended! Would be interested to hear if anyone else has any voids under the slab. Especially those on cut and fill sites (ie. the majority ) My signature is distracting people from my wise posts ... Re: Soil under slab washing away 13Jun 01, 2011 7:45 pm Thanks to all for your contributions. I did finally contact the franchise guy and he came out and offered to retain it - for a price. At that point I spat the dummy and decided to do it myself. I've now built a sandstone retaining wall around two sides of the shed - my first stone wall and it may not look as pretty as some but I'm learning fast and it was very satisfying. I'll follow advice and put in some concrete before I put in the fill. Thanks again everyone. I've got a challenge here. Background is the builder has cut too deep for the slab and the slab is now below the very substantial retaining wall. It's failed occupancy… 0 18373 Hey all Currently renovating our laundry, bought a new washing machine but have found that the drainage hose is alot shorter than the old machine (which I used to get the… 0 17508 Thanks for the insights, that makes perfect sense, and yeah, I will be leaning on the experience of the excavator operator entirely. 6 16104 |