Browse Forums Paving & Concreting Re: Voids under house foundation - how to address? 2Feb 13, 2023 7:43 am Bump... haha well if nothing else I feel a tiny bit better that I haven't completely snoozed on something incredibly important - if 1000+ learned folks view and I've not immediately been told WTF was I thinking. ![]() Re: Voids under house foundation - how to address? 3Feb 13, 2023 9:25 am ![]() Bump... haha well if nothing else I feel a tiny bit better that I haven't completely snoozed on something incredibly important - if 1000+ learned folks view and I've not immediately been told WTF was I thinking. ![]() Hey that's funny, Q. then seeing the cracks extend and get wider shouldn't worry you either? Here's a few things that you can also do while waiting for an geo/engineer/expert to visit your site 1. See if you can tract down the original certified geo report and engineering your local council may have a copy 2.Buy a laser level and check to see if the slab's sagging/ hogging, the tell tale cracking patterns should should match the movements 3.Hire a cheap auger drill a few holes, how would you classify the holes, polystyrene slabs flex, heavy rigid rafts less,etc 4. Talk to your neighbours and ask if they are having similar problems 5. Unfortunately you can't diagnose a problem using words alone.. more info required Cheers Chris Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Voids under house foundation - how to address? 4Feb 13, 2023 9:51 am ![]() ![]() Bump... haha well if nothing else I feel a tiny bit better that I haven't completely snoozed on something incredibly important - if 1000+ learned folks view and I've not immediately been told WTF was I thinking. ![]() Hey that's funny, Q. then seeing the cracks extend and get wider shouldn't worry you either? Here's a few things that you can also do while waiting for an geo/engineer/expert to visit your site 1. See if you can tract down the original certified geo report and engineering your local council may have a copy 2.Buy a laser level and check to see if the slab's sagging/ hogging, the tell tale cracking patterns should should match the movements 3.Hire a cheap auger drill a few holes, how would you classify the holes, polystyrene slabs flex, heavy rigid rafts less,etc 4. Talk to your neighbours and ask if they are having similar problems 5. Unfortunately you can't diagnose a problem using words alone.. more info required Cheers Chris Chris, Appreciate the reply. Umm as I said I was 'bumping' the thread. The progression of the crack have concerned me - hence I'm here, my comment was in rerference to the normal online practive which is folks telling someone they're a moron is they'd done something incorrectly. But as i said, just tryng to bump a thread for a response and appreciate yours. Just curious - as mentioned I know there are decent sized voids under the slab - as I've drilled around the entire perimeter of it and found it consistantly, largely in the areas where the worst pooling of water after heavy rains occurred. So unsure what the laser level will confirm that I cannot already see the results of? RE: 1. I will check but I highly doubt they will have them - these would have been submitted to council in ~1980. I have original hand drafted plans for house etc but no Geo report etc. As mentioned it's all incredibly reactive soil here, clay pan just a few cm down. RE: 3. Could you please clarify what you mean by this? I do not believe the slab is one incorporating polystyrene. RE 4. The neighbours would not be relevant. We're rural and many hundreds of metres between dwellings, also dwellings are very different construction from vastly different construction dates. Also alas there's not a lot of neighbourly spirit - if you know what I mean. RE 5. I did attach an image gallery of some of the cracks, but as stated I am near certain that the cause of this is the voiding under the slab. The cause of the voids I am near certain is the improper guttering and drainage, soil erosion etc. I believe I have corrected these - so would have thought it logical to address the voids. Thank you for your reponse it is appreciated. Re: Voids under house foundation - how to address? 5Feb 13, 2023 10:17 am Quickly Re1. You will need to determine the footing type, depth width, reinforcement Size.. might wish to consider a scan? Re3. The newer slabs are Polystyrene/voids designed to float and flex? Older rafts have grid thickenings, they should try to line them up with masonry walls Re.4 Contour/slope causes water to flow down. do you have drain channels, swales diverting the runoff stormwater away? Re5 the crack show the consequences not the cause, you'll need to address the cause first, search underpinning, just a thought the perimeter footings may need to go deeper, remedy might take a while Also start mapping the data, otherwise you'll never know if things are improving? Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Voids under house foundation - how to address? 6Feb 13, 2023 10:28 am ![]() Quickly Re1. You will need to determine the footing type, depth width, reinforcement Size.. might wish to consider a scan? Re3. The newer slabs are Polystyrene/voids designed to float and flex? Older rafts have grid thickenings, they should try to line them up with masonry walls Re.4 Contour/slope causes water to flow down. do you have drain channels, swales diverting the runoff stormwater away? Re5 the crack show the consequences not the cause, you'll need to adress them first, search underpinning, just a thought the perimeter footings may need to go deeper Appreciate your effort as i'm sure you're busy. RE 1. Yes, this is getting beyond the info I can rattle off with accuracy As mentioned it's ~1982 built. I know it has steel reo grids in it, can see a very small part of this in sections - and also hit this a bunch of times when drilling the holes for the sub-slab termite treatment. Width and length is easy enough, thickness is harder to say. RE3. Understood - highly doubt it's the former, defintely the older style - which I suspect was a poor choice given the highly reactive clay soil here but assume thats just how things were done then. RE4. On atleast 2 sides the water runs away naturally to some degree - my focus had been limiting the water getting there in the first place - hence focus on the gutters which were major issue. Re5. Understood and agree.Am aware of underpinning and will look into again but think this is a tad beyond the anticipated scale of the issue. Atleast I'd certainly hopeso as limited info on that indicates its very expensive - that aside what is needed, is needed. Apreciate your replies and info. Re: Voids under house foundation - how to address? 7Feb 13, 2023 11:17 am RE1 You can't keep drilling the slab unless you have engineering drawings. That's why scanning has become popular get an engineer not an inspector with a new tool? (humour) RE3 deep edge raft beam with grid thickenings is far superior. I've inspected many houses 50year and older hardly any cracking. RE4 It could be gutters, below ground cracks, etc a case of elimination and monitoring RE5 You'll need to check as how far down you need to go.. unfortunately no silver bullet fix If you need to go deeper, maybe beam , offset piles. Make sure the advice giver is a qualified engineer Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Thanks 🙏 I was worried if the roof went on before it’s fixed! 2 13667 Building Standards; Getting It Right! Make sure you don’t dig below footing base level, so you don’t undermine your foundation. Also the backfilling of trench need to allow for stormwater to drain away… 1 11721 Hi all, It appears they have cut and jackhammered the house footing for a service they were planning to run? Will there be any potential structural issues? Noting that… 0 10879 |