Browse Forums Owner Builder Forum Re: Pre-cast Concrete House Build Perth 26Nov 26, 2020 6:05 pm XPS insulation on the outside of the concrete panel is going to be awful. You would need a full blown ERV system as otherwise, you are completely locking all the dampness and water vapour inside, turning such house into a mould pit. Re: Pre-cast Concrete House Build Perth 28Nov 26, 2020 10:30 pm KonkretHaus Did BGC give you balklpark figure for these panels? Through the roof I would imagine going through them? My guys can get them done also, they are done using structural pins that hold the 2 pieces of concrete together on each side of the XPS insulation. Only thing to be mindful of is not to stack them up on top of each other during transport but to get them sent on A frame so they can be edge lifted Yeah - if the structural pins are metal though, then the whole purpose of the XPS is defeated, they need to be non heat conductive pins. Who are your guys also - I'm by no means locked in. BGC were the only people I could find that would entertain the thought of even trying to do it in Wait Awhile. Also how did you do your first floor / second flooring. Is that floating concrete poured on site or did you connect floor joists to the concrete? or something else? Re: Pre-cast Concrete House Build Perth 29Nov 26, 2020 10:37 pm The quote I had for the tilt panel wall - without insulation just a basic tilt panel wall was 160 per square meter. I think BGC said to budget $110 delivered for the precast flooring per sq meter. Don't know about the BCG wall panels - but I priced the connectors at $7000 to cover 100 meters of wall, and the foam was $4000. So all up $11,000 in extra components, expected to use 20-30% less concrete but with more time spent pouring the concrete/laying the ties/foam and finishing the concrete. Re: Pre-cast Concrete House Build Perth 30Nov 26, 2020 11:58 pm dachopper The XPS insulation is in the Center of the concrete... locking all the moisture outside the outer layer of concrete? But also locking moisture/water vapour inside the inner layer? Re: Pre-cast Concrete House Build Perth 31Nov 27, 2020 2:40 am alexp79 dachopper The XPS insulation is in the Center of the concrete... locking all the moisture outside the outer layer of concrete? But also locking moisture/water vapour inside the inner layer? Hi Alex, If you are talking about the latent water that gets released by concrete as is cures? Not much I can do about that - the benefit is that the temperature of the internal concrete should be relatively consistent which will reduce the amount of condensation. We also have a good ventilation plan and live in a moderate wind area which should also help if needed. My research lead me to believe it's one of the best options I can choose to keep the moisture and elements out. I think since it's insulated, you would get more condensation with a gyprock wall than with an insulated concrete panel. Re: Pre-cast Concrete House Build Perth 32Nov 27, 2020 3:10 am Nope, I am talking about water vapours generated inside the house, e.g. bathroom, laundry, kitchen/cooking, breathing, etc. Even when the temperature gradient is not there, vapours will still be eventually turning into the moisture on the backside of your concrete as well as inside internal leaf and eventually corroding reinforcement and damaging the structure. If you will be putting in gyprock on top of your concrete, then a lot of moisture will be accumulating between your concrete and gyprock and gyprock will be eventually rotting. If you are planning to render out, then the render will be falling off. Gyprock + mineral insulation wall, on the other side, is vapour permeable, so the water vapours find they way out as they are easily travelling through the gyprock and mineral insulation and then evaporate through the cavity. Even if they condensate somewhere in the middle, they will easily dry out later. Concrete itself is not very vapour permeable structure (depending on the density, it can be either semi-permeable or not permeable), but XPS has almost zero permeability. You will be completely locking in all the water vapours/moisture inside the structure. Standard ventilation won't be enough, you would need to either go with full blown ERV system which handles ventilation as well as regulates moisture levels or just try living with the windows always open in pretty much all the rooms and esp. south facing ones. Re: Pre-cast Concrete House Build Perth 33Nov 27, 2020 3:47 am alexp79 Nope, I am talking about water vapours generated inside the house, e.g. bathroom, laundry, kitchen/cooking, breathing, etc. Even when the temperature gradient is not there, vapours will still be eventually turning into the moisture on the backside of your concrete as well as inside internal leaf and eventually corroding reinforcement and damaging the structure. If you will be putting in gyprock on top of your concrete, then a lot of moisture will be accumulating between your concrete and gyprock and gyprock will be eventually rotting. If you are planning to render out, then the render will be falling off. Gyprock + mineral insulation wall, on the other side, is vapour permeable, so the water vapours find they way out as they are easily travelling through the gyprock and mineral insulation and then evaporate through the cavity. Even if they condensate somewhere in the middle, they will easily dry out later. Concrete itself is not very vapour permeable structure (depending on the density, it can be either semi-permeable or not permeable), but XPS has almost zero permeability. You will be completely locking in all the water vapours/moisture inside the structure. Standard ventilation won't be enough, you would need to either go with full blown ERV system which handles ventilation as well as regulates moisture levels or just try living with the windows always open in pretty much all the rooms and esp. south facing ones. "Even when the temperature gradient is not there, vapours will still be eventually turning into the moisture on the backside of your concrete as well as inside internal leaf and eventually corroding reinforcement and damaging the structure." Please correct me if I'm wrong, but. My understanding is The benefit of the concrete wall is precisely that the reinforcement is protected from moisture because it is within the concrete. Without the concrete wall it would be exposed ( as cold steel ) directly to the moisture and corrode. The concrete as you say is almost inpermeable and I am very close to the saltwater spray - so trying to pick the best building materials that are going to last the longest. Having said that - we do have a huge amount of windows/ openings / sunlight / skylights in our design, and our Southern wall abuts directly to the neighbours for at least 50%, meaning most of the wall will be protected from the elements. We don't have almost any southern facing windows. Re: Pre-cast Concrete House Build Perth 34Nov 27, 2020 9:08 am dachopper I am very close to the saltwater spray - so trying to pick the best building materials that are going to last the longest. Check out the various codes for marine environmental and maintenance requirements Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Re: Pre-cast Concrete House Build Perth 35Nov 27, 2020 1:14 pm dachopper alexp79 Nope, I am talking about water vapours generated inside the house, e.g. bathroom, laundry, kitchen/cooking, breathing, etc. Even when the temperature gradient is not there, vapours will still be eventually turning into the moisture on the backside of your concrete as well as inside internal leaf and eventually corroding reinforcement and damaging the structure. If you will be putting in gyprock on top of your concrete, then a lot of moisture will be accumulating between your concrete and gyprock and gyprock will be eventually rotting. If you are planning to render out, then the render will be falling off. Gyprock + mineral insulation wall, on the other side, is vapour permeable, so the water vapours find they way out as they are easily travelling through the gyprock and mineral insulation and then evaporate through the cavity. Even if they condensate somewhere in the middle, they will easily dry out later. Concrete itself is not very vapour permeable structure (depending on the density, it can be either semi-permeable or not permeable), but XPS has almost zero permeability. You will be completely locking in all the water vapours/moisture inside the structure. Standard ventilation won't be enough, you would need to either go with full blown ERV system which handles ventilation as well as regulates moisture levels or just try living with the windows always open in pretty much all the rooms and esp. south facing ones. "Even when the temperature gradient is not there, vapours will still be eventually turning into the moisture on the backside of your concrete as well as inside internal leaf and eventually corroding reinforcement and damaging the structure." Please correct me if I'm wrong, but. My understanding is The benefit of the concrete wall is precisely that the reinforcement is protected from moisture because it is within the concrete. Without the concrete wall it would be exposed ( as cold steel ) directly to the moisture and corrode. The concrete as you say is almost inpermeable and I am very close to the saltwater spray - so trying to pick the best building materials that are going to last the longest. Having said that - we do have a huge amount of windows/ openings / sunlight / skylights in our design, and our Southern wall abuts directly to the neighbours for at least 50%, meaning most of the wall will be protected from the elements. We don't have almost any southern facing windows. Concrete is generally waterproofed or protected with render or cladding (when outside) if the want is to protect it from water. It becomes impermeable only at very high densities (e.g. used for massive structures), but I really doubt it is applicable to residential buildings, so in your case it will still likely to be semi-permeable. As I said, I am not worried about elements, I am worried about water vapour from inside the house as it will be creating the main damage. You do not constantly keep all your windows open. Re: Pre-cast Concrete House Build Perth 36Nov 27, 2020 3:55 pm alexp79 dachopper alexp79 Nope, I am talking about water vapours generated inside the house, e.g. bathroom, laundry, kitchen/cooking, breathing, etc. Even when the temperature gradient is not there, vapours will still be eventually turning into the moisture on the backside of your concrete as well as inside internal leaf and eventually corroding reinforcement and damaging the structure. If you will be putting in gyprock on top of your concrete, then a lot of moisture will be accumulating between your concrete and gyprock and gyprock will be eventually rotting. If you are planning to render out, then the render will be falling off. Gyprock + mineral insulation wall, on the other side, is vapour permeable, so the water vapours find they way out as they are easily travelling through the gyprock and mineral insulation and then evaporate through the cavity. Even if they condensate somewhere in the middle, they will easily dry out later. Concrete itself is not very vapour permeable structure (depending on the density, it can be either semi-permeable or not permeable), but XPS has almost zero permeability. You will be completely locking in all the water vapours/moisture inside the structure. Standard ventilation won't be enough, you would need to either go with full blown ERV system which handles ventilation as well as regulates moisture levels or just try living with the windows always open in pretty much all the rooms and esp. south facing ones. "Even when the temperature gradient is not there, vapours will still be eventually turning into the moisture on the backside of your concrete as well as inside internal leaf and eventually corroding reinforcement and damaging the structure." Please correct me if I'm wrong, but. My understanding is The benefit of the concrete wall is precisely that the reinforcement is protected from moisture because it is within the concrete. Without the concrete wall it would be exposed ( as cold steel ) directly to the moisture and corrode. The concrete as you say is almost inpermeable and I am very close to the saltwater spray - so trying to pick the best building materials that are going to last the longest. Having said that - we do have a huge amount of windows/ openings / sunlight / skylights in our design, and our Southern wall abuts directly to the neighbours for at least 50%, meaning most of the wall will be protected from the elements. We don't have almost any southern facing windows. Concrete is generally waterproofed or protected with render or cladding (when outside) if the want is to protect it from water. It becomes impermeable only at very high densities (e.g. used for massive structures), but I really doubt it is applicable to residential buildings, so in your case it will still likely to be semi-permeable. As I said, I am not worried about elements, I am worried about water vapour from inside the house as it will be creating the main damage. You do not constantly keep all your windows open. So, a good recirculating system, or having some external walls that are not concrete would remove the problem you think? Re: Pre-cast Concrete House Build Perth 37Nov 27, 2020 9:09 pm dachopper alexp79 Concrete is generally waterproofed or protected with render or cladding (when outside) if the want is to protect it from water. It becomes impermeable only at very high densities (e.g. used for massive structures), but I really doubt it is applicable to residential buildings, so in your case it will still likely to be semi-permeable. As I said, I am not worried about elements, I am worried about water vapour from inside the house as it will be creating the main damage. You do not constantly keep all your windows open. So, a good recirculating system, or having some external walls that are not concrete would remove the problem you think? Partially the issue can be addressed if you replace XPS with EPS (which is semi-permeable) or mineral insulation (better). But I would still be thinking about installing ERV for the solid walls made of concrete. Re: Pre-cast Concrete House Build Perth 38Nov 29, 2020 12:12 am alexp79 dachopper alexp79 Concrete is generally waterproofed or protected with render or cladding (when outside) if the want is to protect it from water. It becomes impermeable only at very high densities (e.g. used for massive structures), but I really doubt it is applicable to residential buildings, so in your case it will still likely to be semi-permeable. As I said, I am not worried about elements, I am worried about water vapour from inside the house as it will be creating the main damage. You do not constantly keep all your windows open. So, a good recirculating system, or having some external walls that are not concrete would remove the problem you think? Partially the issue can be addressed if you replace XPS with EPS (which is semi-permeable) or mineral insulation (better). But I would still be thinking about installing ERV for the solid walls made of concrete. That is good to know, from memory, I think EPS foam is an easy option I could change to, because the build is in the spray zone, I had a look an the building codes say we have to use a higher grade concrete, which I am guessing means it is more waterproof. Re: Pre-cast Concrete House Build Perth 39Nov 29, 2020 10:03 am Hey Dachopper Yep without data and proofs you are only guessing BTW, There are a few EPS & Esky Homes built in perth. May I suggest you look to more traditional building materials and get it properly engineered and certified hth Designer,Engineer (Civil,Const & Envir),Builder,Concrete & Masonry Contract.Struct Repairs Ideally you would engage a landscaper to give you some insight what they may need in the space to make your vision come to life… 1 10309 We've had the offer of a short term tenant whilst waiting for CDC/DA home approval and demolition for our knock down rebuild. It would achieve a pretty low rent as it's… 0 9886 |