It would be useful if someone could do the calculations adding up all of the material you used (foam, plywood, plastic, glue) and all of the carbon that went into making it and transporting it and compare it head to head with concrete's carbon footprint. I see some doubters in the comments and they might have a point without any data to back it up. My gut tells me that this assembly is overall better environmentally but we can't make building decisions on gut alone. Saying that - love the video, seems solid, and I wish my slab was waterproof and insulated!
Neutrality appreciated. Facts needed. We all have guts but they need to be filled with scientific evidence, not a pretty sounding building concept. I am waiting!
So that comparison is in relation to your style of building. Everything vapor barrier and below are the exact same in a concrete/no concrete floor if we are talking a high performance assembly. So, assuming its a high performance build its the pour of the concrete versus 2 courses of 3/4" ply. and with a plywood board being about 54% carbon I would be pretty confident it would be concrete in a reasonably sized area carbon wise. Take out the foam and vapor barrier out of the concrete pour scenario and now its just an assembly with less performance.
Interesting concept. It would be interesting to see how it compares against a poured slab regarding locations with high seismic activity. Thank you Josh from New Zealand.
Good question. Also what is the cost to dispose of it after the home is renovated or rebuilt. Are the products biodegradable and recyclable? I could go on and on and on.
Thanks Josh for posting this, and for the great article in Fine Home Building. Regarding calculations of materials used to compare the two strategies-- plywood versus concrete slab-- the only thing to consider is the impact of concrete and steel versus that of plywood and finish flooring. Everything from plywood or concrete down is the exact same in either strategy. We're in discussion with an owner about opting for a plywood slab in place of concrete for a house lift so we did the math. The embodied carbon for a 4" 850 sf slab with standard rebar is around 2300 kg of CO2e. But bear in mind that this calc is based on materials in Seattle where we can get concrete with PLC and rebar from an electric arc furnace plant powered by hyrdo. Using more traditional mix designs and rebar from coal fired power plants and the embodied carbon for the same slab might range between 5000-6000 kg CO2e. For a plywood slab of (2) courses of T&G CDX and finish floor of oak, we're estimating the embodied carbon to be in the range of 1000-1300 kg CO2e . If we use salvaged or reclaimed wood flooring the number drops to about 700 kg CO2. So In Seattle, a green building hotbed, we're looking at anywhere from 70%-50% less embodied carbon with the plywood slab assembly. Cost is a different story. Concrete in Seattle is roughly $140/cy, or $1700 total for our slab, rebar adds $800 so material cost for slab is roughly $2500. 2 courses of plywood runs around $3200 with today's pricing; wood flooring @$5/sf is an additional $4200, so plywood slab is pushing $8k. 3x as much. If we bring into consideration the costs to polish and stain the concrete versus costs to sand and finish the floor then the it's closer to 2x as much. If we use the second layer of plywood as the finished floor the price drops even further. Other things to consider are that concrete is more durable and would require less maintenance over time, but also feels colder to the foot underneath and is harder on the joints. All that said I believe that a plywood slab is a great strategy and one that we need to employ more frequently. Yes, it costs more. But embodied carbon needs to be taken into consideration on every project and as Josh says, there's no greater contributor to EC than concrete. If paying twice as much only yielded an EC decrease of 10% I might not recommend it for a small DADU project, although I still would for a much larger project. Thanks again Josh!
I am curious why you’re including finished flooring in this. Is that needed to fully compare to the concrete? Also, I am curious how close the two are today now that lumber prices have come back down to earth.
Maybe just build on a few posts set in ground instead, then beams and joist if you don't want concrete. Why does a building need to be flat touching the ground across floors ?? Makes no sense to reinvent the wheel.
Why 2 layers of 3/4 ply? Seems overkill to me. Perhaps this would be needed in a laundry room where vibration might move the base layer. Otherwise, redundant. I notice this is from "Fine Homebuilding" not practical home building. 🙂
You could potentially get away with a single layer of T&G if you glue the grooves. I've never seen someone try that. You might need to use insulation with a higher compressive value though.
@@niktak1114 Come to think of it, I worked on a remodel of a house(40's built,sort of shack?) that had 2+ foot spacing for floor joists and one layer of t&g heart pine flooring. It was surprisingly solid.
Is anyone worried about rodents with an assembly like this? Gophers seem like they'd find a way through gravel in a heartbeat. Once the poly is ruptured, then what?
Is polystyrene biodegradable? How is it made? Is the manufacturing process greenhouse gas friendly process? What do the trees the plywood is made of need to thrive to make more trees.... oxygen or CARBON DIOXIDE?... Is Less CARBON dioxide good or bad for trees? Which is stronger overall... compressed wood (plywood) or concrete? No wonder so many houses are blown away.
I don't think there are any scientists out there concerned for the lack of CO2 for trees, to the contrary it is environmentally useful to sequester carbon by using wood products produced in a sustainable manor such as on tree farms. So long as we use and replant the trees we use we are taking the carbon they stored, making it useful, and preventing it from rotting and sending the CO2 back into the atmosphere for a long time. You have a valid point on asking questions on how that foam is produced, and in general a lot of foam is horrible for the environment. This manufacturer seems to say that there's isn't so bad - www.insulfoam.com/wp-content/uploads/2014/11/EPS_global_warming.pdf. As far as strength, I wouldn't want to tile on top of this assembly, but any other flooring should work well i would think. The frame of the house itself is anchored to the concrete footing in the same manner that all houses need to be based on the code (even though a lot of old houses in my area aren't anchored at all and just rely on gravity!) It's an interesting concept and we builders need to (carefully) think outside of the box for the benefit of all our futures'.
@@frattman You are assuming trees are replanted. No evidence here or source of the trees provided. In addition to the polystyrene there are also 4 or 5 other nonbiodrgradable products used in the entire process. How are they made? How much energy is expended and how much of the earth is defaced. I agree we must look outside the box but innovation is not always to the benefit of the end consumer or the world. Selling products on the back of an ideology is what's going on. Plants need carbon dioxide and the more they have, the more oxygen is produced. We have been sold an upside down cake. I am not buying it one bit. Think how lush the earth was when it was warmer, when more carbon dioxide was in the atmosphere. The oxygen levels likely were through the roof which would have been awesome for us humans. Recent scientific studies if one cares to research actually indicates the earth is cooling not warming. To find it you'd have to dig through the online censorship so good luck with that.
Bashing concrete is too easy. strength for strength, concrete is hard to beat. The reason it takes up so much of the CO2 pie is because we use so much of it. Most building constructions are 100x overengineered, to account for sloppy workmanship, and because extra concrete is cheaper than the architects's person-hours tariff. If concrete were to be taxed heavily (and therefore used frugally) it would be one of the greenest construction-materials there is. Water-proof, termite-proof, weather-proof, fire-resistant, no VOCs and tough as nails.. what more can you ask for? Please do an exergy calculation on all the SIGA engineered tapes and zip-sheaths and Schluter membranes and other fancy $tuff that the cool kids are touting these days, and concrete is just better. When compared apples-to-apples.
@@Guy4UnderDog No. Rebar is too espensive, when used in compression. The aggregates in concreate are better bang for the buck. Rebar prevents it from failing under tension, If you could magically delete the cement/aggregate mix from an RCC building, the steel would flop around aimlessly. Granted, a different construction (e.g. a steel cabinet) can be strong, but for a given price, concrete is hard to beat. (On planet earth, anno 2024)
The people who constantly talk about CO2 emissions are the same people who caused fossil fuel prices to be a record 7 year high. Couldn't be any coincidence... Lol!
@@steelyspielbergo See Folks, THIS is why we are in the situation we find ourselves today. Because of people like Matt. Matt can't seem to find the words to explain why he supports his corrupt politicians. Don't be a "Matt". Mmmk?
Sorry, I don't buy it. Look at all the energy that is used to produce all the other products, equipment, etc. Plus, the cost of labor and additional materials.
WELL SAID. People are just crazy. There are at least 4 or 5 nonbiodegradable products all of which likely used a hell of a lot of energy and waste byproduct to create. I AIN'T BUYING THIS IDEOLOGY EITHER. Madness!
There is about a net zero chance that you have a lesser carbon footprint doing things this way. 20 years in commercial construction leads me to believe that you probably used up far more fossil fuels with the excessive layers of material, whose exact carbon footprint has not been quantified here. Most likely on purpose. Then you have to think about the exorbitant price increase to the customer, and for what? So that they can feel better about themselves because some shmo told them things, and they don't know any better so they believe it. And..... A 2 layer plywood floor floating on top of gravel is just ridiculous. Some day someone will be tearing that apart and cursing the idiot who built it, instead of the true idiot who designed it. Either way, stupid idea and you are most certainly NOT, saving the environment by one single iota.
![Lp. Сердце Вселенной #60 РОЖДЕНИЕ ЛОЛОЛОШКИ [Финал] • Майнкрафт](http://i.ytimg.com/vi/YoR0pAV9FVQ/mqdefault.jpg)
It would be useful if someone could do the calculations adding up all of the material you used (foam, plywood, plastic, glue) and all of the carbon that went into making it and transporting it and compare it head to head with concrete's carbon footprint. I see some doubters in the comments and they might have a point without any data to back it up. My gut tells me that this assembly is overall better environmentally but we can't make building decisions on gut alone. Saying that - love the video, seems solid, and I wish my slab was waterproof and insulated!
Neutrality appreciated. Facts needed. We all have guts but they need to be filled with scientific evidence, not a pretty sounding building concept. I am waiting!
So that comparison is in relation to your style of building. Everything vapor barrier and below are the exact same in a concrete/no concrete floor if we are talking a high performance assembly. So, assuming its a high performance build its the pour of the concrete versus 2 courses of 3/4" ply. and with a plywood board being about 54% carbon I would be pretty confident it would be concrete in a reasonably sized area carbon wise. Take out the foam and vapor barrier out of the concrete pour scenario and now its just an assembly with less performance.
I would start here: materialspalette.org/palette/
Interesting concept. It would be interesting to see how it compares against a poured slab regarding locations with high seismic activity. Thank you Josh from New Zealand.
California has entered the chat
great video! so does the finished floor just sit directly on top of the plywood?
Looks good! Any heating mat?
Is this floor up to code or did you get a varience?
What is the additional cost compared to traditional concrete?
Good question.
Also what is the cost to dispose of it after the home is renovated or rebuilt.
Are the products biodegradable and recyclable?
I could go on and on and on.
Have you ever had any issues with the building inspector/ plans examiner in doing this type of floor?
Thanks Josh for posting this, and for the great article in Fine Home Building. Regarding calculations of materials used to compare the two strategies-- plywood versus concrete slab-- the only thing to consider is the impact of concrete and steel versus that of plywood and finish flooring. Everything from plywood or concrete down is the exact same in either strategy. We're in discussion with an owner about opting for a plywood slab in place of concrete for a house lift so we did the math. The embodied carbon for a 4" 850 sf slab with standard rebar is around 2300 kg of CO2e. But bear in mind that this calc is based on materials in Seattle where we can get concrete with PLC and rebar from an electric arc furnace plant powered by hyrdo. Using more traditional mix designs and rebar from coal fired power plants and the embodied carbon for the same slab might range between 5000-6000 kg CO2e. For a plywood slab of (2) courses of T&G CDX and finish floor of oak, we're estimating the embodied carbon to be in the range of 1000-1300 kg CO2e . If we use salvaged or reclaimed wood flooring the number drops to about 700 kg CO2. So In Seattle, a green building hotbed, we're looking at anywhere from 70%-50% less embodied carbon with the plywood slab assembly. Cost is a different story. Concrete in Seattle is roughly $140/cy, or $1700 total for our slab, rebar adds $800 so material cost for slab is roughly $2500. 2 courses of plywood runs around $3200 with today's pricing; wood flooring @$5/sf is an additional $4200, so plywood slab is pushing $8k. 3x as much. If we bring into consideration the costs to polish and stain the concrete versus costs to sand and finish the floor then the it's closer to 2x as much. If we use the second layer of plywood as the finished floor the price drops even further. Other things to consider are that concrete is more durable and would require less maintenance over time, but also feels colder to the foot underneath and is harder on the joints. All that said I believe that a plywood slab is a great strategy and one that we need to employ more frequently. Yes, it costs more. But embodied carbon needs to be taken into consideration on every project and as Josh says, there's no greater contributor to EC than concrete. If paying twice as much only yielded an EC decrease of 10% I might not recommend it for a small DADU project, although I still would for a much larger project. Thanks again Josh!
I am curious why you’re including finished flooring in this. Is that needed to fully compare to the concrete? Also, I am curious how close the two are today now that lumber prices have come back down to earth.
Interested in trying this. Wondering about using foamed glass aggregate instead of gravel. Then foamed glass panels instead of the EPS. Any thoughts?
Wouldn’t xps foam have more compression strength and not some up any potential water? Im curious why use eps over xps?
How the hell do you actually keep that whole floor level?
It's actually easier to level. You don't have a race with set time.
Maybe just build on a few posts set in ground instead, then beams and joist if you don't want concrete. Why does a building need to be flat touching the ground across floors ??
Makes no sense to reinvent the wheel.
Termites will love it
So who’s the guinea pig owner?
What a brilliant way to lay a concrete free floor thanks for the video. 👍
Why make things complicated? Any future repairs or upgrades under the floor would disturb the floors stability. Wood buried under concrete? Longevity?
Did I not understand something? The point of the plywood was to not have concrete for the floor....
Why 2 layers of 3/4 ply? Seems overkill to me. Perhaps this would be needed in a laundry room where vibration might move the
base layer. Otherwise, redundant. I notice this is from "Fine Homebuilding" not practical home building. 🙂
You could potentially get away with a single layer of T&G if you glue the grooves. I've never seen someone try that. You might need to use insulation with a higher compressive value though.
@@niktak1114 Come to think of it, I worked on a remodel of a house(40's built,sort of shack?) that had 2+ foot spacing for floor joists and one layer of t&g heart pine flooring. It was surprisingly solid.
Fukin awesome
Is anyone worried about rodents with an assembly like this? Gophers seem like they'd find a way through gravel in a heartbeat. Once the poly is ruptured, then what?
Rats and ants....both are problems.
Is polystyrene biodegradable?
How is it made?
Is the manufacturing process greenhouse gas friendly process?
What do the trees the plywood is made of need to thrive to make more trees.... oxygen or CARBON DIOXIDE?...
Is Less CARBON dioxide good or bad for trees?
Which is stronger overall... compressed wood (plywood) or concrete? No wonder so many houses are blown away.
I don't think there are any scientists out there concerned for the lack of CO2 for trees, to the contrary it is environmentally useful to sequester carbon by using wood products produced in a sustainable manor such as on tree farms. So long as we use and replant the trees we use we are taking the carbon they stored, making it useful, and preventing it from rotting and sending the CO2 back into the atmosphere for a long time. You have a valid point on asking questions on how that foam is produced, and in general a lot of foam is horrible for the environment. This manufacturer seems to say that there's isn't so bad - www.insulfoam.com/wp-content/uploads/2014/11/EPS_global_warming.pdf. As far as strength, I wouldn't want to tile on top of this assembly, but any other flooring should work well i would think. The frame of the house itself is anchored to the concrete footing in the same manner that all houses need to be based on the code (even though a lot of old houses in my area aren't anchored at all and just rely on gravity!) It's an interesting concept and we builders need to (carefully) think outside of the box for the benefit of all our futures'.
@@frattman You are assuming trees are replanted. No evidence here or source of the trees provided.
In addition to the polystyrene there are also 4 or 5 other nonbiodrgradable products used in the entire process. How are they made? How much energy is expended and how much of the earth is defaced.
I agree we must look outside the box but innovation is not always to the benefit of the end consumer or the world. Selling products on the back of an ideology is what's going on. Plants need carbon dioxide and the more they have, the more oxygen is produced. We have been sold an upside down cake. I am not buying it one bit.
Think how lush the earth was when it was warmer, when more carbon dioxide was in the atmosphere. The oxygen levels likely were through the roof which would have been awesome for us humans. Recent scientific studies if one cares to research actually indicates the earth is cooling not warming. To find it you'd have to dig through the online censorship so good luck with that.
Plywood is never flat.
and concrete is?
Advantech is very flat
Bashing concrete is too easy. strength for strength, concrete is hard to beat. The reason it takes up so much of the CO2 pie is because we use so much of it. Most building constructions are 100x overengineered, to account for sloppy workmanship, and because extra concrete is cheaper than the architects's person-hours tariff. If concrete were to be taxed heavily (and therefore used frugally) it would be one of the greenest construction-materials there is. Water-proof, termite-proof, weather-proof, fire-resistant, no VOCs and tough as nails.. what more can you ask for?
Please do an exergy calculation on all the SIGA engineered tapes and zip-sheaths and Schluter membranes and other fancy $tuff that the cool kids are touting these days, and concrete is just better. When compared apples-to-apples.
the majority of concrete is used to protect rebar from rusting.
@@Guy4UnderDog No. Rebar is too espensive, when used in compression. The aggregates in concreate are better bang for the buck. Rebar prevents it from failing under tension, If you could magically delete the cement/aggregate mix from an RCC building, the steel would flop around aimlessly. Granted, a different construction (e.g. a steel cabinet) can be strong, but for a given price, concrete is hard to beat. (On planet earth, anno 2024)
The people who constantly talk about CO2 emissions are the same people who caused fossil fuel prices to be a record 7 year high. Couldn't be any coincidence... Lol!
derp
@@steelyspielbergo See Folks, THIS is why we are in the situation we find ourselves today. Because of people like Matt. Matt can't seem to find the words to explain why he supports his corrupt politicians. Don't be a "Matt". Mmmk?
Have you ever even tried to understand the basic science around green house gases? its really not that complicated.
Seems like so many possible failure points.
Sorry, I don't buy it. Look at all the energy that is used to produce all the other products, equipment, etc. Plus, the cost of labor and additional materials.
WELL SAID.
People are just crazy.
There are at least 4 or 5 nonbiodegradable products all of which likely used a hell of a lot of energy and waste byproduct to create.
I AIN'T BUYING THIS IDEOLOGY EITHER. Madness!
The assembly is the same either way the only difference is plywood verse concrete.
@@RobertBierma sorry, no it's not.
There is about a net zero chance that you have a lesser carbon footprint doing things this way. 20 years in commercial construction leads me to believe that you probably used up far more fossil fuels with the excessive layers of material, whose exact carbon footprint has not been quantified here. Most likely on purpose.
Then you have to think about the exorbitant price increase to the customer, and for what? So that they can feel better about themselves because some shmo told them things, and they don't know any better so they believe it.
And..... A 2 layer plywood floor floating on top of gravel is just ridiculous. Some day someone will be tearing that apart and cursing the idiot who built it, instead of the true idiot who designed it.
Either way, stupid idea and you are most certainly NOT, saving the environment by one single iota.
how about because it's warmer and insulated the floor then?
How could 1.5" of subfloor have a higher carbon footprint than 6" of concrete?
Stop with the greenhouse gas bullshit.
Lol, why?