Browse Forums Flooring & Floor Covering 1 Jul 17, 2009 2:07 pm I am keen to go with polished concrete flooring through most of the house but my builder has thrown me a couple of curve balls. I think he knows what he is talking about and I trust him but I'm trying to find alternative solutions. Problem 1. I want to have a walk in shower with a polished concrete floor. His concern was that the wet areas need to be properly wet sealed to meet building regulations. In another thread this was addressed and the solution was to put in some sort of membrane. However the builder is now telling me that I will need to have a shower door to meet the regulations. I don't want the shower door. Does anyone know if there is a way around this? Problem 2. The guys at Progrind have given me a sample which I like and wish to use but the builder tells me that it won't meet regulations because the size of the aggreagate is too small. What are the standards for aggregate size? Brian Re: Polished Concrete snags 2Jul 17, 2009 2:33 pm Hi Brian, Problem 1: I would talk to your architect / drafts person as I cannot imagine how using the concrete alone would change this, I would expect with all floor coverings you would face this issue. Problem 2: AS2870 which is the residential slabs and footings code does not actually specify a minimum size aggregate. It specifies a minimum MPA (20, but for polished concrete you really want 25-32mpa) and a *nomimal maximum* aggregate size of 20mm. Structural strength does not just come from the aggregate, it comes from the complete design mix and also the mesh that is used. Regards, Ben Vander Veen PROGRIND AUSTRALIA Maintenance Free Polished Concrete, without coatings! www.progrind.com.au Re: Polished Concrete snags 3Jul 17, 2009 3:20 pm Ben, thanks for the quick reply. It sounds like it should be doable. I'll push him a little bit and get some more details. Brian Re: Polished Concrete snags 4Jul 17, 2009 3:36 pm Here is a notice from the MBAV a couple years ago. Hope it helps. Keep in mind that you probably need to re-apply the sealer on any polished concrete floor every 5 years or so. You're builder is talking about the shower screen as a water stop, to ensure water doesn't flow onto the bathroom floor. As it says in this article, the best way to install polished concrete to a wet area is to set down the house slab, flash and seal the bathroom, apply the waterproofing membrane and pour a concrete screed over the top, which will be polished. THis would then ensure that the whole floor is waterproofed. Design Considerations for Polished Concrete in Wet Areas The current practices for waterproofing polished concrete floors in showers and wet areas have not been properly considered and methods for sealing these floors can lead to water escaping from the wet areas into adjoining areas. Some of the current practices used in waterproofing polished concrete involves treating the concrete with an admixture to prevent water penetration and spraying the surface with a transparent sealer. The objective of this is to waterproof the floor and retain the look of polished concrete. This method can fail because the transparent sealing coat can be affected by cleaning chemicals used in showers. The coating does not comply with the requirements of AS/NZS4858, namely membranes used in showers. One part of the key requirements of the test to meet AS 4858 is to subject the membranes to chemical attack. Many showers have failed because the waterproofing system has been damaged by chemicals. Other issues are, the sealing coat applied to polished concrete may not bond to the waste outlet, which can cause a leak at the pipe penetration. Also movement at the wall/floor junction could rupture the transparent sealer creating a lack of proper flashing at the wall/floor junction. Depending on the type of shower screen to be used, it may not be possible to install a water stop at the perimeter of the shower. The problem here is that if a water stop was installed during the placement of the concrete it would have to finish above the level of the polished concrete to be effective. The lack of a proper water stop could allow water to escape into adjoining areas. To address these issues a preferred option is to fully recess the wet area and apply a waterproof membrane including a wall/floor junction flashing to the perimeter of the bathroom. A concrete screed could then be placed, graded to the wastes, cured and then polished. The concrete would then finish flush with a water stop at the doorway. To achieve this outcome in concrete or brick buildings, a number of design considerations arise. For suspended floors the bathroom must be set down 100mm and drainage flanges installed to the wastes. Where the bathroom is a slab on the ground, the drainage pipes should have a minimum diameter of 80mm. The membrane is then installed with the perimeter flashings being designed to finish 50mm above the finished surface of the concrete floor. The vertical junction of the shower wall will also have been sealed at this time. Concrete for the polished floor is then installed. It is a requirement that showers have fall to wastes in accordance with AS 3740 2004. In buildings where sheet lining is used, the method for waterproofing the floors is identical with the flashing applied to the face of the wall sheet. The up stand in the waterproofing will be covered by the skirting tiles to the perimeter of the bathroom. The methods described above still require a high quality water-resistant admixture added to the decorative concrete during the batching process. This is to prevent any ingress of moisture into the concrete slab due to sealer breakdown which could lead to contamination or fungal growth. Blog is now up - http://www.jbdave.blogspot.com/ Re: Polished Concrete snags 5Jul 17, 2009 4:34 pm jbdave, There are no surface coatings in the method of polishing that we actual use. While we do use an impregnator in our polishing process (it forms a membrane in the capilaries), there is no topical coatings or reapplication of the product. Regards, Ben Vander Veen PROGRIND AUSTRALIA Maintenance Free Polished Concrete, without coatings! www.progrind.com.au Re: Polished Concrete snags 6Jul 17, 2009 4:37 pm Ben, How would you apply an anti slip finish to an area such as a shower base ? Blog is now up - http://www.jbdave.blogspot.com/ Re: Polished Concrete snags 7Jul 17, 2009 5:35 pm Hi Brian, I'm not sure about the second issue, but I can't see that there is a problem with the shower. We were going to have polished concrete in the shower in our ensuite, and have no door on our shower. We had no problems with the builder, he was happy to do it. The only reason we aren't going ahead with it in the ensuite now is because we wanted under tile heating in there. Good luck 'chelle We have a hand-over date...15/10...but I won't hold my breath! http://people-in-glass-houses.blogspot.com/ Re: Polished Concrete snags 8Jul 17, 2009 6:19 pm jbdave Ben, How would you apply an anti slip finish to an area such as a shower base ? jbdave, There is not one. When wet, the polished concrete has a greater COF than most natural polished stones. Regards, Ben Vander Veen PROGRIND AUSTRALIA Maintenance Free Polished Concrete, without coatings! www.progrind.com.au Re: Polished Concrete snags 9Jul 18, 2009 4:20 pm jbdave Here is a notice from the MBAV a couple years ago. Hope it helps. Jbdave, thanks for posting the info. I'll be going for the uncoated concrete as Ben has described. I've got a sample and when you you run your fingers across it they seem to "grab" a bit. I can't see slipperiness being an issue. When you get a chance watch the last couple of videos. The cracks are pretty bad, it's almost as though he hasn't put any reo in that corner and hasn't compacted/levelled… 2 3360 You are fine. The concrete is never going to explode. Worse case scenario is that it develops a crack from different rates of expansion but hopefully it's got some… 5 4509 |