Browse Forums Paving & Concreting 1 Mar 16, 2014 10:06 am Hi, My house was built in the 70s, southern end of Qld Sunshine Coast. Fairly high water table and the house is poorly situated on the lowest part of the block. The ground floor of the house we want to be a rumpus room and laundry + 2nd bathroom. Nothing fancy, just practical. Ground floor slab is poor quality - some parts powdery, some bits of wood and crap in the mix. There are a couple of reasonably narrow cracks, no wider than 3mm. End result is that moisture comes up in a few places - the dreaded negative hydrostatic pressure problem. One option is to clean out all the obvious crappy parts of the slab, widen out the cracks and then repair with something like Nitomortar. Following that I could apply an epoxy membrane like Emer-Proof Aqua-Barrier. This would then require covering with tiles, carpet or lino. Will take some time for the preparation and I'm very time poor. Another option is to lay another, fairly shallow slab - say 75 mm thick. This has the obvious disadvantage of lowering the usable height under the house - won't effect us, as none of the family are tall - but will impact on potential resale in the future. An advantage of this plan is that it will help avoid rain inundation (outside-in at ground level) which sometimes happens when we got a lot of rain in a short period of time. Also, someone else will do it, not me. I can then polish the concrete and seal it with a top coat, as we like that polished concrete look. My main concern with the new slab option is that the rising damp will still come up the original slab. If the new slab has appropriate water proofing layer (the thick plastic sheeting stuff that is used for new slabs) then the rising damp shouldn't be able to come through the new slab but what happens to that moisture? Could it be a problem? Thanks for any advice. Mark. Re: Rising damp through slab - how to resolve? 2Mar 16, 2014 11:02 am Don't suppose you could go another direction and dig around the outside of the house and install some comprehensive drainage pipe like what is done for retaining walls? that way you actually solve the problem rather than attempting to work around it? Slooowwwwly getting a Manhatten 35 in Middleton Grange Re: Rising damp through slab - how to resolve? 3Mar 16, 2014 7:16 pm Thanks for your reply. While work needs to be done on the outside anyway (excavating a perimeter, evening up the front yard so that run off flows away from the house etc.) it wouldn't solve the rising damp. The rising damp is not isolated to raining periods - it happens even after weeks of dry weather and I believe it's the result of a constantly high water table, rather than a temporary situation caused by rain run off. That's why I think another slab will solve two different problems, IF the trapped moisture between the two slabs won't cause other issues. Re: Rising damp through slab - how to resolve? 4Mar 16, 2014 8:02 pm http://www.environment.nsw.gov.au/resou ... ngdamp.pdf I still recon exposing the damp course or whatever (air drains they call them) Slooowwwwly getting a Manhatten 35 in Middleton Grange Firstly the ableflex that has been installed needs (manufactures specification) a sealant cap over the top, preventing water draining down between the slab and the… 3 7793 Thanks for your advice. So far i have not noticed any issues with doors and windows. Builder advised they will organise drainers to inspect 2 weeks ago but no further… 7 18821 Have look at your house plans and you will probably find that brick articulation joint has been missed. Maximum allowable spacing is 6M or 5.5M for a wall with window… 17 20615 |