Browse Forums DIY, Home Maintenance & Repair 1 May 03, 2012 2:41 pm Very worried, Our house is 5 1/2 years old. We have a concrete water tank built under our deck. It is concrete block construction with concrete infill. It has been "sealed" on the inside with a rubber-like black paint. I drained the tank to take a look inside and see if it needed any maintenance (I had noticed very slow drip coming from the other side in our subfloor). When I was under there I noticed a small area of sealant was blistered and open showing the block behind. When I pressed on this area my finger pushed right through the concrete!! I found that I could remove the face of large sections of the tank blockwork with my hand. The infill seems in tact. However there is a rusty colour to some of the concrete crumble that I have removed. I have contacted the builder who said that he will fix it but I want to make sure I know what has to be done to completely eliminate the problem so that there is no chance of it returning. Will it keep eating through even after it is dried? Has anyone got any ideas on how to repair this problem?? Would appreciate any advice. Thanks, WorriedBen Here are some photos http://www.flickr.com/photos/77905605@N04/7137964829/in/photostream http://www.flickr.com/photos/77905605@N04/7137978199/in/photostream http://www.flickr.com/photos/77905605@N04/7137978933/in/photostream Please look at the videos to get an idea of what I mean. http://youtu.be/PE2JCqbK6zk http://youtu.be/2fITy6E6d_4 http://youtu.be/6XoBBO11K9w Re: Concrete blocks breaking down/deteriorating severely!! 2May 03, 2012 5:44 pm Its very hard to say from the photos but I would be concerned that the bitumen paint(?) appears only to run part way across the floor. The wall would also need sealing from the outsidE to stop ground water from attacking the block walls, has this been done? The damage you show may actually not be from water coming from the inside but rather from the outside. Get the builder to take a look. @builderforlife Building inspector and passionate about construction When you need an expert to take a look. Re: Concrete blocks breaking down/deteriorating severely!! 3May 03, 2012 8:02 pm You are right about the floor. The bottom edge where the wall meets the floor has a strip of plastic membrane that extends about 100mm up the wall and 100mm onto the floor. The paint covers the entire wall and extends about 50mm past this membrane on the floor leaving about 99% of the floor paint free. I am certain that the moisture is entering from the tank as two of the opposite side are completely visible from the subfloor and although there is heaps of efflorescence there is no source of moisture on the other side. The other two sides are rendered and don't show any visible signs of damage. Thanks for the quick response. It is very hard to find advice as a leading supplier and even the Cement Concrete & Aggregates Australia (CCAA) and had not heard of concrete blocks degrading like this. Surely someone has seen something like this before?? Re: Concrete blocks breaking down/deteriorating severely!! 4Jun 22, 2012 10:06 pm BFL may be correct with the water coming from the outside or either the bitumen paint/waterproofing compound has reacted with the cement or the builder has used substandard blocks to start with. What is the ground water like at your place? Some areas have very hard water that can have a corrosive effect and is known to react with certain other compounds like cement. Is it very brackish or brown ? Stewie Those span tables can be pushed a little for a low deck if you dont mind a little flex. Last deck I did, I pushed it a little and it was still rock solid - no noticeable… 6 13768 How long is a "long period"? For a few weeks, it should be ok. It also depends on the area you live in...I would let your neighbours know that you will be away too and… 1 28574 |