Browse Forums Paving & Concreting 1 Oct 13, 2020 1:30 pm Hello all, I am planning to extend the size of my alfresco area. So far I have a council permitted verandah built that doubles the covered alfresco area. At the moment, I have my standard concrete alfresco floor that is part of the home foundation. I want to get another concrete slab of 5mx5m to extend under my new verandah. This slab would butt up against the alfresco slab and eventually be tiled. My current plans were below: Tile the whole concreted area. Pin slab to house foundation to minimise any cracking of tiles. Slop new concrete slab away from home to a grated drain by licensed plumbers. Slab would have reo and done by a reputable concreting company. Additional information: Waffle Slab P class New home 6 months. Is there anything I should be concerned about with my plans? Can pinning this slab on a 'reactive site' cause issues with my homes foundation (cracking of the alfresco slab)? Or anything I am missing? Cheers, Rhys Re: Extending alfresco slab 2Oct 14, 2020 9:37 pm Rhys26 Hello all, I am planning to extend the size of my alfresco area. So far I have a council permitted verandah built that doubles the covered alfresco area. At the moment, I have my standard concrete alfresco floor that is part of the home foundation. I want to get another concrete slab of 5mx5m to extend under my new verandah. This slab would butt up against the alfresco slab and eventually be tiled. My current plans were below: Tile the whole concreted area. Pin slab to house foundation to minimise any cracking of tiles. Slop new concrete slab away from home to a grated drain by licensed plumbers. Slab would have reo and done by a reputable concreting company. Additional information: Waffle Slab P class New home 6 months. Is there anything I should be concerned about with my plans? Can pinning this slab on a 'reactive site' cause issues with my homes foundation (cracking of the alfresco slab)? Or anything I am missing? Cheers, Rhys Hi Rhys, A couple of things you should consider-they may or may not be relevant to your situation but worth thinking about: 1. The waffle slab and the new slab will likely behave differently in response to changing conditions so it's often better to allow differential movement. A structural engineer would be the person to provide a bit better info but rather than pinning the slab together and trying to 'force' them together, incorporating expansion/slip joints between the two might work better. An example might be that the new slab could be more prone to normal seasonal movement than the waffle slab so it would need to be allowed for. 2. Similar to the above, pinning the slabs together may prevent the waffle slab from moving as it was designed to. A 5m x 5m x 0.2m (say) slab which is behaving differently from the waffle slab might not just result in problems at the join of the two, but problems within the waffle slab itself as one 5m long section is not behaving the same as the rest of the slab. 3. Whats the likely condition of the ground below the area of slab extension? You mention a P site classification. Is it due to fill (controlled or not), trees, old buildings on site, poor ground etc. and could that impact the new slab? 4. Not had much to do with waffle slabs, but generally maintaining uniform moisture conditions under or near slab perimeters is good practice. The construction of the new slab will selectively protect a 5m wide section of the ground next to the existing slab from drying out or wetting up which would likely impact the soils under the slab over time. Not such a worry if the rest of the slab is protected as well (via apron) but if not, the risk is setting up varying moisture contents (and variable degrees of movement) under the slab which can cause problems. If your patio is going to be 35 sqm then that's going to need Council Approval. The fact that they previously approved your 25sqm patio will be irelevant 1 5509 Ask for some kickplate to be added and also for tradies to be requested to use lanyards on tools on that side of the building. Be respectful and have the discussion… 1 1698 There is insufficient information to give a meaningful answer. You should talk to council planning. Apart from building construction issues, if you are adding floor area… 1 7988 |