Browse Forums Building A New House 1 Jun 10, 2020 3:22 pm Okay, he are my thoughts on how modern technologies can reduce the cost and speed of average-sized house slab with footings/beams, let's say 200 m2 on soils class of up to H2 without piering requirements (as per Cupolex spec), NSW rates: 1) Day 1 - excavate and remove 20 cm of soil, create natural soil incline to drainage, remove excess soil, install drainage, plumbing inspection - resources/costs: excavator wet hire ($1000/day), bobcat dry hire ($500/day), plumber with apprentice ($800 per day, plumbing materials - $1000), removal of 40 cubic meters of soil - $2K tops - $5,300 2) Day 2 - back fill the drainage, bobcat dry hire ($500/day), 2 general labourers ($250x2 per day), 10 cubes of sand delivered ($500x2), compaction (2 plate compactors for hire ($125x2 per day) - $2,500 2) Day 3 - installation of Cupolex 350 system with Pontex ribs, Cupolex Thermal Wrap, minimum reinforcement, form work, termite caps, pre-pour inspection - 2 formwork carpenter installers ($5K for Cupolex materials, $500x2 per day for carpenters, $400 for termite caps, $100 for reo, $300 for inspection, $200 for form work timber) - $7,000 4) Day 4 - pour, concrete finish - 4 concreters ($500x4 per day), pump hire 6 hours incl. travel ($1500), 35 cubes of 32mpa concrete with 10 kg/m3 HelixSteel premix (built-in reinforcement) and Radmyx premix (built-in waterproofing for concrete) - $260 (32 mpa concrete with Radmyx)+$80 (Helix)=$340*35=$12K - $15,500 Total cost - $30.3K or a little over $150 per sqm, 4 days of work. What you get - stiffened foundation with 20-30% higher stiffness than conventional slab system (due to Helix Steel, Cupolex and Radmyx products used) coming also with built-in underslab ventilation and advanced slab heave resistance, which is also completely waterproof and thermally insulated from the ground + perimeter drainage. Due to savings in time provided, house framing can be started as soon as on the second week. Thoughts and comments are welcome. Re: House slab on H2 in 4 days 2Jun 11, 2020 11:13 pm alexp79 Okay, he are my thoughts on how modern technologies can reduce the cost and speed of average-sized house slab with footings/beams, let's say 200 m2 on soils class of up to H2 without piering requirements (as per Cupolex spec), NSW rates: 1) Day 1 - excavate and remove 20 cm of soil, create natural soil incline to drainage, remove excess soil, install drainage, plumbing inspection - resources/costs: excavator wet hire ($1000/day), bobcat dry hire ($500/day), plumber with apprentice ($800 per day, plumbing materials - $1000), removal of 40 cubic meters of soil - $2K tops - $5,300 2) Day 2 - back fill the drainage, bobcat dry hire ($500/day), 2 general labourers ($250x2 per day), 10 cubes of sand delivered ($500x2), compaction (2 plate compactors for hire ($125x2 per day) - $2,500 2) Day 3 - installation of Cupolex 350 system with Pontex ribs, Cupolex Thermal Wrap, minimum reinforcement, form work, termite caps, pre-pour inspection - 2 formwork carpenter installers ($5K for Cupolex materials, $500x2 per day for carpenters, $400 for termite caps, $100 for reo, $300 for inspection, $200 for form work timber) - $7,000 4) Day 4 - pour, concrete finish - 4 concreters ($500x4 per day), pump hire 6 hours incl. travel ($1500), 35 cubes of 32mpa concrete with 10 kg/m3 HelixSteel premix (built-in reinforcement) and Radmyx premix (built-in waterproofing for concrete) - $260 (32 mpa concrete with Radmyx)+$80 (Helix)=$340*35=$12K - $15,500 Total cost - $30.3K or a little over $150 per sqm, 4 days of work. What you get - stiffened foundation with 20-30% higher stiffness than conventional slab system (due to Helix Steel, Cupolex and Radmyx products used) coming also with built-in underslab ventilation and advanced slab heave resistance, which is also completely waterproof and thermally insulated from the ground + perimeter drainage. Due to savings in time provided, house framing can be started as soon as on the second week. Thoughts and comments are welcome. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Here's an example of the fibre type reo failing in a pavement. I have seen several examples of it failing over the years I don't trust it. Re: House slab on H2 in 4 days 3Jun 11, 2020 11:25 pm Hey insider, have you specifically seen examples of Helix Steel (which are steel rebars btw, not fibres) failing? They are on market for almost 20 years and have done multitude of serious commercial and industrial projects, and seem to be quite trusted global vendor. Were those failures specifically attributed to the failures of reinforcement or to something else? How many conventionally reinforced slabs have you seen failing? Re: House slab on H2 in 4 days 4Jun 16, 2020 6:36 am Hi alex79 In general I like what your saying especially the first part about grading the site away from the footings. This alone would significantly reduce the slab heave risk in highly reactive soils. The example I have show was steel fibre reo they seems to perform well if the situation is ideal or what is expected. In circumstances where it is not ideal or an abnormal factor arises they appear to fail dramatically. Does that sound familiar ? It reminds me of another major change to the building industry where if things are not done properly they fail and that is the waffle slab on highly reactive soil. Knowing what we know now and if we could turn back the clock would we introduce the waffle pod slab? So in my option combining the fibre reo with waffle pods would be a step away from achieving a stable slab that meets the consumers expectations. I like the idea of the cuplex system, polyvoid and other similar products especially if they are on screw piles. They should be an improvement for reducing slab heave but they are yet to truely tested by climate extremes so time will tell if those systems are a solution. We need new ideas and innovations along with greater enforcement of the existing regulations so keep nutting out the issues. Re: House slab on H2 in 4 days 5Jun 16, 2020 12:21 pm Hi Insider, Thanks for the response. I am simply wondering how come steel fibre reo is failing with cracks as conventional reo is supposed to start working after the concrete is cracked already? Re: House slab on H2 in 4 days 6Jun 16, 2020 12:30 pm Probably a question for an experienced structural engineer specialising in this area. I would imagine there is research information available as well. Swinburne's advanced materials laboratory is probably a place where it may have been tested. Re: House slab on H2 in 4 days 7Jun 17, 2020 11:32 am alexp79 Okay, he are my thoughts on how modern technologies can reduce the cost and speed of average-sized house slab with footings/beams, let's say 200 m2 on soils class of up to H2 without piering requirements (as per Cupolex spec), NSW rates: 1) Day 1 - excavate and remove 20 cm of soil, create natural soil incline to drainage, remove excess soil, install drainage, plumbing inspection - resources/costs: excavator wet hire ($1000/day), bobcat dry hire ($500/day), plumber with apprentice ($800 per day, plumbing materials - $1000), removal of 40 cubic meters of soil - $2K tops - $5,300 2) Day 2 - back fill the drainage, bobcat dry hire ($500/day), 2 general labourers ($250x2 per day), 10 cubes of sand delivered ($500x2), compaction (2 plate compactors for hire ($125x2 per day) - $2,500 2) Day 3 - installation of Cupolex 350 system with Pontex ribs, Cupolex Thermal Wrap, minimum reinforcement, form work, termite caps, pre-pour inspection - 2 formwork carpenter installers ($5K for Cupolex materials, $500x2 per day for carpenters, $400 for termite caps, $100 for reo, $300 for inspection, $200 for form work timber) - $7,000 4) Day 4 - pour, concrete finish - 4 concreters ($500x4 per day), pump hire 6 hours incl. travel ($1500), 35 cubes of 32mpa concrete with 10 kg/m3 HelixSteel premix (built-in reinforcement) and Radmyx premix (built-in waterproofing for concrete) - $260 (32 mpa concrete with Radmyx)+$80 (Helix)=$340*35=$12K - $15,500 Total cost - $30.3K or a little over $150 per sqm, 4 days of work. What you get - stiffened foundation with 20-30% higher stiffness than conventional slab system (due to Helix Steel, Cupolex and Radmyx products used) coming also with built-in underslab ventilation and advanced slab heave resistance, which is also completely waterproof and thermally insulated from the ground + perimeter drainage. Due to savings in time provided, house framing can be started as soon as on the second week. Thoughts and comments are welcome. Hi Alex, - How is the 20%-30% calculated and what is advanced slab heave resistance? - Waffle or stiffened raft slab would not need piers on H2 site classification, unless you have tree or fill issue which is the same case with Cupolx? - On H2 site class according to AS 2870: Waffle slab: 385x300 on external + 385x110internal at 1.2m cts Stiffened raft slab 600x300 at 4m cts Cupolex 410x300 at much greater cts? how this can have greater capacity? - Does this system complies with AS 2870? - Will this be designed by Cupolex engineers? what will stop other incompetent engineers to not use and certify it while not having a good understanding of it Re: House slab on H2 in 4 days 8Jun 17, 2020 12:28 pm Hi Structural.Review, Thanks for your questions, they are very relevant. 20-30% is just my rough estimate based on calcs I have received on my slab from HelixSteel (which is generally increased shear strength, durability & toughness, MOR) and comparison to the conventionally reinforced rafted slab as well RadMyx (improves concrete strength by 17.5%) and Cupolex data (see below). Can be more, can be less. Cupolex system with minor soil replacement allows to remove of piers even when they are required for other systems, i.e. they mentioned several cases when this has been done. Cupolex allows to use internal beams same way as you use with do it with waffle pods, in addition they also have their own internal beam system specifically designed for unstable system and called Pontex which allows to place internal beams at customised centers depending on the soil bearing capacity. Also, you can't really compare Cupolex to waffle slab due to that each Cupolex pod has also a central pike which works as additional support point. FYI, Cupolex claim that their load capacity on average exceeds Australian standards 6 times (which is AS 2870). Yes, slab system to be designed by Cupolex certified engineers. Re: House slab on H2 in 4 days 9Jun 17, 2020 2:04 pm alexp79 Hi Structural.Review, Thanks for your questions, they are very relevant. 20-30% is just my rough estimate based on calcs I have received on my slab from HelixSteel (which is generally increased shear strength, durability & toughness, MOR) and comparison to the conventionally reinforced rafted slab as well RadMyx (improves concrete strength by 17.5%) and Cupolex data (see below). Can be more, can be less. Cupolex system with minor soil replacement allows to remove of piers even when they are required for other systems, i.e. they mentioned several cases when this has been done. Cupolex allows to use internal beams same way as you use with do it with waffle pods, in addition they also have their own internal beam system specifically designed for unstable system and called Pontex which allows to place internal beams at customised centers depending on the soil bearing capacity. Also, you can't really compare Cupolex to waffle slab due to that each Cupolex pod has also a central pike which works as additional support point. FYI, Cupolex claim that their load capacity on average exceeds Australian standards 6 times (which is AS 2870). Yes, slab system to be designed by Cupolex certified engineers. Thanks for reply Alex, Replacing top soil and rolling it back is allowed upto 300mm maximum or it has to be controlled which none of the builder will do, I would say you will definitely need piers under Cupolex or any other slab once the movement is above 100mm due to trees, unless footings are significant deep to provide the required moment capacity due to settlement. AS 2870 can't be used for Cupolex as 32mpa is outside the scope of the code, section 3.1.1. (i) AS 2870-2011. I have seen a design produced by non Cupolex engineer unfortunately, my concern is that we have inexperienced certifiers and builders who wants to cut the corners which will result in home owner being stuck with consequences for saving on slab which is minimal to the failure. Anyways, thanks for comments. Re: House slab on H2 in 4 days 10Jun 17, 2020 2:45 pm Correct me if I am wrong, but you can still use shallower footings even if movement is above 100 mm due to trees or extremely reactive soils, as long as the slab is stiffened enough? E.g. in Northern countries they often use 250-300 mm very well stiffened monolithic slabs (ie you virtually get slab-wide footing, stiffened with 2 layers of 12 mm bars forming 200x200 cells) on extremely reactive clays and they have freezing factor over there too! Why do you think builders won't be able to do controlled fill? It is not really that hard and I have done it for my house slab (following layered compaction technique and with radioactive compaction testing). 32 mpa concrete is for extra strength in this particular case, it may not be a specific Cupolex requirement per se, in fact slab on top of Cupolex can be even 60 mm slab with 25 mpa concrete. Re: House slab on H2 in 4 days 11Jun 17, 2020 3:30 pm alexp79 Correct me if I am wrong, but you can still use shallower footings even if movement is above 100 mm due to trees or extremely reactive soils, as long as the slab is stiffened enough? E.g. in Northern countries they often use 250-300 mm very well stiffened monolithic slabs (ie you virtually get slab-wide footing, stiffened with 2 layers of 12 mm bars forming 200x200 cells) on extremely reactive clays and they have freezing factor over there too! Why do you think builders won't be able to do controlled fill? It is not really that hard and I have done it for my house slab (following layered compaction technique and with radioactive compaction testing). 32 mpa concrete is for extra strength in this particular case, it may not be a specific Cupolex requirement per se, in fact slab on top of Cupolex can be even 60 mm slab with 25 mpa concrete. You can use monolithic slabs which needs significant more concrete and it is different then to waffle and Cupolex? this is beneficial when we are dealing with extreme movements, with existing trees I believe it is cheaper to do piers where required as you have settlement issues and not heave problem unless you are removing the tree. They will do control fill if you educate them and supervise them, ask Builders what is the difference between rolled and controlled fill, volume housing builders which do majority of work, do not have understanding of it and they never do it, they never found the edge beams of waffle slabs into controlled or natural soil, this is partially their fault and partially engineers who donot detail their slab design properly and leave it to builder to put a waffle slab edge beams on rolled fill, you just need to check some of the new build houses in Melbourne to see houses less than 3 month old with cracks. In an industry where we can't design and build a simple residential slab properly (volume housing mainly) from Australian Standards, I wouldn't suggest introducing more complex systems, you are technically competent but majority of home owners are not. Re: House slab on H2 in 4 days 12Jun 17, 2020 3:52 pm Structural.Review alexp79 Correct me if I am wrong, but you can still use shallower footings even if movement is above 100 mm due to trees or extremely reactive soils, as long as the slab is stiffened enough? E.g. in Northern countries they often use 250-300 mm very well stiffened monolithic slabs (ie you virtually get slab-wide footing, stiffened with 2 layers of 12 mm bars forming 200x200 cells) on extremely reactive clays and they have freezing factor over there too! Why do you think builders won't be able to do controlled fill? It is not really that hard and I have done it for my house slab (following layered compaction technique and with radioactive compaction testing). 32 mpa concrete is for extra strength in this particular case, it may not be a specific Cupolex requirement per se, in fact slab on top of Cupolex can be even 60 mm slab with 25 mpa concrete. You can use monolithic slabs which needs significant more concrete and it is different then to waffle and Cupolex? this is beneficial when we are dealing with extreme movements, with existing trees I believe it is cheaper to do piers where required as you have settlement issues and not heave problem unless you are removing the tree. They will do control fill if you educate them and supervise them, ask Builders what is the difference between rolled and controlled fill, volume housing builders which do majority of work, do not have understanding of it and they never do it, they never found the edge beams of waffle slabs into controlled or natural soil, this is partially their fault and partially engineers who donot detail their slab design properly and leave it to builder to put a waffle slab edge beams on rolled fill, you just need to check some of the new build houses in Melbourne to see houses less than 3 month old with cracks. In an industry where we can't design and build a simple residential slab properly (volume housing mainly) from Australian Standards, I wouldn't suggest introducing more complex systems, you are technically competent but majority of home owners are not. My point re monolithic slabs is that if Cupolex engineers claim that they can achieve similar stiffness and with their system, then it should be more or less inter-replaceable? Although mono slabs require more concrete and reo (btw, reo costs can be significantly lower than conventional slab if Helix Steel steel fibers are used), they also require significantly less ground works (excavation of beams/extra set outs) and form work set up efforts when comparing to conventional rafted slabs, plus you can also sum up concrete and ground works required for excavation of the piers too in order to run a proper side by side costs/effort comparison. In the end of the day, considering the cost of labour, you might end up with not so significant difference when comparing to conventional rafted slab on piers. 20 extra cubes of concrete cost only $4-$5K which is what you roughly pay for 2 extra days of excavation and form work laborers, plus piers will add up even more. Let's also keep in mind that waffle pods are not really recommended for highly reactive soils. I am not totally against piers as long as they are properly inter-connected to the underlying slab to prevent soil getting under the piers when slab lifts off due to soil movement or at least protective flexible caps are used. I don't think a lot of builders/engineers following that. But yes, I completely agree with your point that we just can't really push new technologies to mass market without proper control and supervision by professionals. Re: House slab on H2 in 4 days 13Jun 19, 2020 11:01 am alexp79 Structural.Review alexp79 Correct me if I am wrong, but you can still use shallower footings even if movement is above 100 mm due to trees or extremely reactive soils, as long as the slab is stiffened enough? E.g. in Northern countries they often use 250-300 mm very well stiffened monolithic slabs (ie you virtually get slab-wide footing, stiffened with 2 layers of 12 mm bars forming 200x200 cells) on extremely reactive clays and they have freezing factor over there too! Why do you think builders won't be able to do controlled fill? It is not really that hard and I have done it for my house slab (following layered compaction technique and with radioactive compaction testing). 32 mpa concrete is for extra strength in this particular case, it may not be a specific Cupolex requirement per se, in fact slab on top of Cupolex can be even 60 mm slab with 25 mpa concrete. You can use monolithic slabs which needs significant more concrete and it is different then to waffle and Cupolex? this is beneficial when we are dealing with extreme movements, with existing trees I believe it is cheaper to do piers where required as you have settlement issues and not heave problem unless you are removing the tree. They will do control fill if you educate them and supervise them, ask Builders what is the difference between rolled and controlled fill, volume housing builders which do majority of work, do not have understanding of it and they never do it, they never found the edge beams of waffle slabs into controlled or natural soil, this is partially their fault and partially engineers who donot detail their slab design properly and leave it to builder to put a waffle slab edge beams on rolled fill, you just need to check some of the new build houses in Melbourne to see houses less than 3 month old with cracks. In an industry where we can't design and build a simple residential slab properly (volume housing mainly) from Australian Standards, I wouldn't suggest introducing more complex systems, you are technically competent but majority of home owners are not. My point re monolithic slabs is that if Cupolex engineers claim that they can achieve similar stiffness and with their system, then it should be more or less inter-replaceable? Although mono slabs require more concrete and reo (btw, reo costs can be significantly lower than conventional slab if Helix Steel steel fibers are used), they also require significantly less ground works (excavation of beams/extra set outs) and form work set up efforts when comparing to conventional rafted slabs, plus you can also sum up concrete and ground works required for excavation of the piers too in order to run a proper side by side costs/effort comparison. In the end of the day, considering the cost of labour, you might end up with not so significant difference when comparing to conventional rafted slab on piers. 20 extra cubes of concrete cost only $4-$5K which is what you roughly pay for 2 extra days of excavation and form work laborers, plus piers will add up even more. Let's also keep in mind that waffle pods are not really recommended for highly reactive soils. I am not totally against piers as long as they are properly inter-connected to the underlying slab to prevent soil getting under the piers when slab lifts off due to soil movement or at least protective flexible caps are used. I don't think a lot of builders/engineers following that. But yes, I completely agree with your point that we just can't really push new technologies to mass market without proper control and supervision by professionals. I understand and agree that they can be inter-replaceable, this is also similar to modifying a waffle slab if the engineer is competent enough. Generally by increasing the height you will get 3 times more stiffness than increasing the width (check 4.6 AS 2870 -2011), based on this, most of the time you will end up increasing the slab depth rather than modifying the width of beams or spacing, with waffle slabs you can achieve this by stacking up the pods or deepening the beams in stiffened raft slabs, will this be achievable with Cupolex given the maximum height is 350? Some engineers will not connect the pier into slab as they have used piers for bearing/settlement and designed (hopefully) the slab to take swelling pressure, also calculating the uplift pressure and designing the reinforcements and connection between the pier and slab edge beam is not an easy computation. Re: House slab on H2 in 4 days 14Jun 19, 2020 11:53 am Yes, Cupolex can also stack up, plus they manufacture domes up to 70 cm in height. Also, noone restricts from digging deeper edge beams too into the ground too. They also have Cupolex Rialto system (plastic pipes filled with concrete placed under the domes) which is specifically designed to replace up to 2 m of engineered fill! How can slab can take the swelling pressure if it floating? Will the swelling pressure lift the slab off the piers? 8 6156 I'll be here once a week, lets make that Mondays. If you have a question, this will be the day I will log in for a look around.. If your lucky, sooner. Ask away...… 0 6371 13 6634 |