Interesting idea. If done right it will work. But what about cost? Those LVL studs, ground rated plywood, 2 sheets of 3/4 plywood for the floor etc don't come cheap. How does the cost compare to a typical concrete slab/walls with foam insulation? Or ICF?
This is a very interesting experiment Steve - thank you for taking a chance on unique methodologies. As an architect I think the water management issues, while tricky, are solvable. I would love to hear more about the structural components, how such a light building resists uplift and overturning, the calculations for the subgrade wood walls resisting the the soil backfill, etc. Thank you for so generously sharing knowledge with your community.
Great video, love to see the alternatives to a concrete slab/foundation. Any chance we get to see an episode with big red where you go through the plans/details for this house?? Also, what part of the country is this again? Is there in consideration or concern for frost heaving? And I might have missed it, but how is the timber foundation secured to the gravel footing?
I like the idea of the wood floor instead of concrete and would like to see it installed. I would go with a concrete, shallow frost protected footer and stem wall. Overall concrete use would be reduced considerably.
No criticism…. I’ve built many wood foundations. Questions. Does the floor have similar strengths as a pour floor with respect to holding lateral pressure at bottom of wall? Will there be reverse joist hangers installed at top of joists? Are there hangers installed at the ends of joists?
That's a good question because in the Canadian Wood Council book on PWF, they don't use this lapped sheathing floor system, I assumed due to a lack of lateral strength. They recommend slab, or a wood floor joist built on sleeper footings. I wondered the same about their floor system
We bought our house in MN 3 years ago with a full 8 foot wood foundation. Inspection caught bowing walls but dry even with the very poor grading. Reworked the terms and closed on the house with plans on getting the walls fixed. Probably have talked to 50 contractors not a single one wants to touch it. Do love how inexpensive heating and cooling is.
Interested to know stud sizes and spacing. I believe 2x6 on 12" centers is standard. Here Steve has 2x8 LVL studs 16 OC. Those walls will never bow. I think the LVL is great, but definitely overkill and very expensive. I'm interested in doing this on a new build but want to balance cost with mitigating issues like you're having.
Walls are 2x6, 12 on center all the blocking was left out, no hangars on the stud tops there are a couple of areas where the doubled top plate splices are within a foot of each other. Along with being in a heavy clay soil. If it was built right I can easily see 100+ years.
@@multipotentialite The walls are being pushed in to the interior of the house. I have a concrete slab that the studs just rest against at the bottom. I'm thinking about escavating, pushing them back plumb, sistering adding blocking and hangers. Adding some egress windows then waterproof and regrade.
Great video Steve! Radiant concrete slabs are super comfortable but concrete floors aren't everyone's favorite option. Wood basement floors are something we see detailed about 10%-15% of the time on custom home builds. Like you mentioned wood floors are just a little softer feeling even when they are done very strong and rigid like this project. --Jay from AMC Foam
Wooden boats do rot, and saltwater helps against that, but in the 19th century (possibly earlier) they were sheathed in copper plating to improve longevity. Since most PT preservatives are copper based you can see the principle is sound. I have no doubts this will last a long time since great care was taken for detail against water. As others said concrete alternatives are needed. Love the experimentation!
I’d take a wood foundation built by you and Jake any day over a production builder concrete foundation. The craftsman matters. A lot! Logically the deeply buried sections where there is no aerobic activity should be fine. The place to worry would be the areas near the surface where aerobic and microbic activity is high. Think of where a fence post fails. It’s not deep…is the area right around the surface.
Couple things: 1. The foundation wood is not considered ground contact wood. That's a lower pressure treated wood. Foundation Grade is the correct term for buried in ground. 2. If I understood you correctly the footer plate at the walkout level is not a good idea do to racking of the walkout. 3. I built mine and experienced a little racking but it's been 35 years and I haven't regretted it at all. Thanks for the video always enjoy the content.
I looked into wooden foundations over 20 years ago. The department of forestry had them going into locations in Wisconsin back even before I was looking at them. They've been there for years. They've held up for years. There's no reason not to use wood as long as it's done right. I'm sure there's probably still some information around from the department of forestry in Wisconsin on wooden foundations.
Excellent vid, and I have thought about it a lot. Even suggested it and Polyguard enthusiastically said, “Great idea!” Now, I know that wasn’t the genesis; clearly it was in the works. But the concept is solid AND more accessible to areas where homeowners already battle the builder status quo to get basements. I’d love to see your detail on it. I think it’s promising, especially for the mass timber movement.
I'd love to see you detail this with Big Red. I can see several advantages to this aside from the environmental ones. Screwed up concrete is a lot harder to fix than screwed up framing, plus concrete walls take up a lot of space with very low R-value, so I could see this being very advantageous in small homes where space is at a premium. I would think the same principles of water management apply below grade as above grade. Providing plenty of drainage and drying, as well as preventing hydrostatic pressure should allow a wood foundation to last as long as a concrete one.
I read several of the comments and the key words are "when properly done". I know of several houses built in my area that were built in the 1980's using wood foundations. The primary reason was that the general contractor could use their own carpentry crew to build the foundation and not be dependent on the concrete subcontractor schedule. I have always been concerned in how well the waterproofing was installed. The method used was to apply Grace ice and water shield to the treated plywood. I know of one house built in the late 90's that only used two layers of black plastic. That house is showing deterioration of the plastic at the part of the foundation that is above ground. I think that the current owner will be facing a very expensive repair soon. Fortunately we get very little rainfall but can get a lot of moisture from spring snowmelt.
I was thinking about wood foundations with Structural Geofoam back fill at $50 to a $100 bucks a yard it would keep all the dirt and load away from the wall. Or maybe foam glass (Glavel) back fill. They are building highways out of geofoam.
Steve, my specialty/business is structural engineering, but my passion is moving the needle towards sustainablilty in our building stock and I think this is a promising concept. The embodied energy savings by eliminating the concrete are epic if the building can stand the test of time. From a structural point of view the areas I would want to pay close attention to include: 1) requiring a thorough knowledge of the soil type below the building. If there is settlement or heaving vertically or laterally there could be severe issues 2) for areas with high structural lateral loads (wind or earthquake) close attention will need to be given to uplifting forces. In high wind regions this could be resolved with a cable ground anchor system such as the Manta Ray Utility Anchor System (I'm not enforcing that particular brand, just a reference) 3) If folks wanted to achieve this in future buildings that might have more windows on the ground floor then I would suggest substituting the flat 2x12 PT sill for a 6x12 PT or Western Red Cedar bottom plate. If this member could span the entire shear wall length as one side pushes down it could resist the other side pulling up even without the ground anchors
Hi Steve! Right now on the Green Building Advisor website there is an article by Jon Harrod about the Ephoca Cold Climate Heat Pump which doesn't need an outdoor unit. It can mount on the wall or ceiling and you can also get it with an ERV included. There is also video from Taitum Engineering about the unit on this site. Have you heard of them before?
Interesting. The grandfather of a friend of mine built his own house way back in the day, and basically put beams on large stones and went up from there. No actual ground contact. Like concrete footings without the concrete.
I love the idea just one question at 2:28 in the video you say there is a 2x12 is this horizontal to hold the pack the dirt or vertical to hold the walls? And is the 2x12 incorporated into the waterproof assembly?
I may have missed it, but I’m curious as to how the framing/ the building is attached to the ground. The typical play is to use anchor bolts to hold the mud plates to the foundation walls and footings, or use brackets to hold beams to concrete piers if doing a pier and beam system. But I didn’t catch how the framing is anchored to the ground below here, especially if the plywood raft is not the structural foundation and the 2x12 treated plates are the foundation ‘walls.’ What I’m getting at is, typically the weight of the concrete is enough to anchor the framing to and keep the house from just lifting off and moving in extreme weather events. I don’t see this building being anchored to the ground thru the foundation plates because that would introduce a path for water to come thru the ground via capillary action and rot the 2x12 plates. So has the weight of the building been determined to be enough by the engineer to hold it down in place?
The Southern Pine Council (they are credited with much of the research for permanent wood foundations) have details on their site for anchoring. I don't remember the exact details, but I believe it entails helical screws or spikes driven through the treated doubled bottom plates of the walls and straps. Iv'e done a couple farm buildings using what I refer to as "hybrid permanent wood foundation". Basically, I used a concrete strip footings to which I bolted doubled bottom plates. The rest of the details are pretty much what are shown in the video. I used treated 2x8's 12" on center for the portion that was below grade (mainly to make the local inspector happy).
have you used superior walls... premade concrete with steel studs attached on gravel as a footing? I used it on a hybrid house about 20 years ago, along with open web joists and truss roof, which is uncommon where I am on Long Island (mostly stick frame and wood Is). the Premade foundation was bolted as it was craned into place, no down time to start construction immediately, allowing the house to be completed in a few months
I love this! Trying to avoid concrete myself on a future build. Are these "slabless slabs" suitable for garages? Can they handle heavy concentrated loads like the weight bearing on car tires? How would you finish the floor for such an application - maybe large-format tile over Schluter-DITRA?
Very interesting concept Steve, being able to not use concrete for the foundation is really intriguing. Please update us regularly on how this works out. How is this tied into the ground by the way to prevent it being lifted up during a storm? Is it just relying on the weight of the building? The Glavel product you showed a while back might also be a good fit for something like this to ensure proper drainage space below the building?
I'm confused about the lack of frost wall - very interested in a frost protected shallow wood foundation - is that what this is? At least that front edge?
My current house was built with a concrete slab, but wood foundation walls for the full basement. Owned it for less than 2 years now, but the basement is warm, dry and seems otherwise no different from any other basement of the 1980s era. Would be curious to get your take on this construction method from an energy usage vs comfort vs cost vs long term reliability. It is not very common construction these days and we did have at least one bank that had reservations when our mortgage broker was hunting for rates. We did some due diligence and found that although some people in general would state to stay clear of them, most of the knowledgeable commentary was that if properly built and maintained to keep water in control said it should last as long as a concrete foundation and would outperform a cinder block foundation. Warm basements in winter and lower energy bills are advantages, along with generally lower building costs.
Is the Halo Subterra taped? Why put it on top of the Stego? What about the warm moist air inside getting cold on the Stego and condensing? Does it have somewhere to go?
I think that i read that the original White House was/is built on a wood foundation along with many other eastern US historical buildings. Also correct me if i'm mistaken but Matt Reisinger built his house on an existing concrete slab and used 2 inches of foam and then double 3/4 plywood for a first-floor subfloor system to account for mechanical systems. I looked at wood basements 20 years ago when we built our forever house, the only drawback was the doubt/uneasiness of the local building department officials although it was code compliant. Keep pushing the envelope with the new old ideas and new state of the art materials. Modern technology needs to not forget about history and the old school ways.
Does that subterra deter ants or other insects and what tape do you use to connect them? I’ve seen ICF foam pics of ants tunneling through it. It wasn’t Nudura, just basic foam.
Is there anything done to combat uplift? I don't have any trouble imaging that the details in place will keep it dry, but I wonder about high winds or frost heave. Thanks!
Here's an interesting article. S&arch for Wood Foundations - Picasso Does Foundations I'd give a direct link but YT has a habit of deleting comments with such.
Steve, i'm sorry to report, all those boats did actually rot away. There are like a handful left in the museums of this world. On the other hand, all those buildings from that time build with stone, if they survived the bombs of the Second World War, they are still here and kicking!
Glavel is a replacement for gravel, but with some insulation properties. It wouldn't replace any wood. In this situation they could have replaced the gravel and foam with glavel, but glavel is cost-prohibitive in most parts of the country.
Didn’t you also poo-poo wood foundations in a podcast a while back? If so, I give you credit for revisiting the system, but you should probably have a little more patience for the naysayers in the comments.
I would like you to Big Red the details of this especially the floor. When back in the studio. thanks.
Love seeing this. We need to find concrete substitutes. Hope to see updates on this in the future.
Plywood foundations were around the 60s and were not uncommon in the NW. Good to see you bringing them up again.
Interesting idea. If done right it will work. But what about cost? Those LVL studs, ground rated plywood, 2 sheets of 3/4 plywood for the floor etc don't come cheap. How does the cost compare to a typical concrete slab/walls with foam insulation? Or ICF?
This is a very interesting experiment Steve - thank you for taking a chance on unique methodologies. As an architect I think the water management issues, while tricky, are solvable. I would love to hear more about the structural components, how such a light building resists uplift and overturning, the calculations for the subgrade wood walls resisting the the soil backfill, etc. Thank you for so generously sharing knowledge with your community.
Great video, love to see the alternatives to a concrete slab/foundation. Any chance we get to see an episode with big red where you go through the plans/details for this house?? Also, what part of the country is this again? Is there in consideration or concern for frost heaving? And I might have missed it, but how is the timber foundation secured to the gravel footing?
Know of 100 year old wood foundations still good. Will be doing my own shortly
I like the idea of the wood floor instead of concrete and would like to see it installed. I would go with a concrete, shallow frost protected footer and stem wall. Overall concrete use would be reduced considerably.
No criticism…. I’ve built many wood foundations. Questions.
Does the floor have similar strengths as a pour floor with respect to holding lateral pressure at bottom of wall?
Will there be reverse joist hangers installed at top of joists? Are there hangers installed at the ends of joists?
That's a good question because in the Canadian Wood Council book on PWF, they don't use this lapped sheathing floor system, I assumed due to a lack of lateral strength. They recommend slab, or a wood floor joist built on sleeper footings. I wondered the same about their floor system
We bought our house in MN 3 years ago with a full 8 foot wood foundation. Inspection caught bowing walls but dry even with the very poor grading. Reworked the terms and closed on the house with plans on getting the walls fixed. Probably have talked to 50 contractors not a single one wants to touch it. Do love how inexpensive heating and cooling is.
Interested to know stud sizes and spacing. I believe 2x6 on 12" centers is standard. Here Steve has 2x8 LVL studs 16 OC. Those walls will never bow. I think the LVL is great, but definitely overkill and very expensive. I'm interested in doing this on a new build but want to balance cost with mitigating issues like you're having.
What do you mean by bowing?
Walls are 2x6, 12 on center all the blocking was left out, no hangars on the stud tops there are a couple of areas where the doubled top plate splices are within a foot of each other. Along with being in a heavy clay soil. If it was built right I can easily see 100+ years.
@@tylerlongmore9004 Do you mean the middle of the wall is lower than the ends or that the wall is being pushed towards the interior of the house?
@@multipotentialite The walls are being pushed in to the interior of the house. I have a concrete slab that the studs just rest against at the bottom. I'm thinking about escavating, pushing them back plumb, sistering adding blocking and hangers. Adding some egress windows then waterproof and regrade.
Great video Steve! Radiant concrete slabs are super comfortable but concrete floors aren't everyone's favorite option. Wood basement floors are something we see detailed about 10%-15% of the time on custom home builds. Like you mentioned wood floors are just a little softer feeling even when they are done very strong and rigid like this project. --Jay from AMC Foam
Wooden boats do rot, and saltwater helps against that, but in the 19th century (possibly earlier) they were sheathed in copper plating to improve longevity. Since most PT preservatives are copper based you can see the principle is sound. I have no doubts this will last a long time since great care was taken for detail against water. As others said concrete alternatives are needed. Love the experimentation!
I’d take a wood foundation built by you and Jake any day over a production builder concrete foundation. The craftsman matters. A lot!
Logically the deeply buried sections where there is no aerobic activity should be fine. The place to worry would be the areas near the surface where aerobic and microbic activity is high. Think of where a fence post fails. It’s not deep…is the area right around the surface.
So awesome to see it done well and outside of convention, thanks again for sharing!
Couple things:
1. The foundation wood is not considered ground contact wood. That's a lower pressure treated wood. Foundation Grade is the correct term for buried in ground.
2. If I understood you correctly the footer plate at the walkout level is not a good idea do to racking of the walkout.
3. I built mine and experienced a little racking but it's been 35 years and I haven't regretted it at all.
Thanks for the video always enjoy the content.
I looked into wooden foundations over 20 years ago. The department of forestry had them going into locations in Wisconsin back even before I was looking at them. They've been there for years. They've held up for years. There's no reason not to use wood as long as it's done right. I'm sure there's probably still some information around from the department of forestry in Wisconsin on wooden foundations.
Excellent vid, and I have thought about it a lot. Even suggested it and Polyguard enthusiastically said, “Great idea!” Now, I know that wasn’t the genesis; clearly it was in the works. But the concept is solid AND more accessible to areas where homeowners already battle the builder status quo to get basements. I’d love to see your detail on it. I think it’s promising, especially for the mass timber movement.
I'd love to see you detail this with Big Red. I can see several advantages to this aside from the environmental ones. Screwed up concrete is a lot harder to fix than screwed up framing, plus concrete walls take up a lot of space with very low R-value, so I could see this being very advantageous in small homes where space is at a premium. I would think the same principles of water management apply below grade as above grade. Providing plenty of drainage and drying, as well as preventing hydrostatic pressure should allow a wood foundation to last as long as a concrete one.
This is a good discovery program, you’re a modern age Columbus mate!
It would be great to build an identical completely concrete ICF shed next to it and see which one performs and lasts longer.
I read several of the comments and the key words are "when properly done". I know of several houses built in my area that were built in the 1980's using wood foundations. The primary reason was that the general contractor could use their own carpentry crew to build the foundation and not be dependent on the concrete subcontractor schedule. I have always been concerned in how well the waterproofing was installed. The method used was to apply Grace ice and water shield to the treated plywood. I know of one house built in the late 90's that only used two layers of black plastic. That house is showing deterioration of the plastic at the part of the foundation that is above ground. I think that the current owner will be facing a very expensive repair soon. Fortunately we get very little rainfall but can get a lot of moisture from spring snowmelt.
I was thinking about wood foundations with Structural Geofoam back fill at $50 to a $100 bucks a yard it would keep all the dirt and load away from the wall. Or maybe foam glass (Glavel) back fill. They are building highways out of geofoam.
Steve, my specialty/business is structural engineering, but my passion is moving the needle towards sustainablilty in our building stock and I think this is a promising concept. The embodied energy savings by eliminating the concrete are epic if the building can stand the test of time. From a structural point of view the areas I would want to pay close attention to include:
1) requiring a thorough knowledge of the soil type below the building. If there is settlement or heaving vertically or laterally there could be severe issues
2) for areas with high structural lateral loads (wind or earthquake) close attention will need to be given to uplifting forces. In high wind regions this could be resolved with a cable ground anchor system such as the Manta Ray Utility Anchor System (I'm not enforcing that particular brand, just a reference)
3) If folks wanted to achieve this in future buildings that might have more windows on the ground floor then I would suggest substituting the flat 2x12 PT sill for a 6x12 PT or Western Red Cedar bottom plate. If this member could span the entire shear wall length as one side pushes down it could resist the other side pulling up even without the ground anchors
I am waiting for Bamboo Studs to come out of Asia soon.
It will last plenty long. Nice job.
Hi Steve! Right now on the Green Building Advisor website there is an article by Jon Harrod about the Ephoca Cold Climate Heat Pump which doesn't need an outdoor unit. It can mount on the wall or ceiling and you can also get it with an ERV included. There is also video from Taitum Engineering about the unit on this site. Have you heard of them before?
Interesting. The grandfather of a friend of mine built his own house way back in the day, and basically put beams on large stones and went up from there. No actual ground contact. Like concrete footings without the concrete.
I love the idea just one question at 2:28 in the video you say there is a 2x12 is this horizontal to hold the pack the dirt or vertical to hold the walls? And is the 2x12 incorporated into the waterproof assembly?
I may have missed it, but I’m curious as to how the framing/ the building is attached to the ground. The typical play is to use anchor bolts to hold the mud plates to the foundation walls and footings, or use brackets to hold beams to concrete piers if doing a pier and beam system. But I didn’t catch how the framing is anchored to the ground below here, especially if the plywood raft is not the structural foundation and the 2x12 treated plates are the foundation ‘walls.’
What I’m getting at is, typically the weight of the concrete is enough to anchor the framing to and keep the house from just lifting off and moving in extreme weather events. I don’t see this building being anchored to the ground thru the foundation plates because that would introduce a path for water to come thru the ground via capillary action and rot the 2x12 plates. So has the weight of the building been determined to be enough by the engineer to hold it down in place?
The Southern Pine Council (they are credited with much of the research for permanent wood foundations) have details on their site for anchoring. I don't remember the exact details, but I believe it entails helical screws or spikes driven through the treated doubled bottom plates of the walls and straps.
Iv'e done a couple farm buildings using what I refer to as "hybrid permanent wood foundation". Basically, I used a concrete strip footings to which I bolted doubled bottom plates. The rest of the details are pretty much what are shown in the video. I used treated 2x8's 12" on center for the portion that was below grade (mainly to make the local inspector happy).
have you used superior walls... premade concrete with steel studs attached on gravel as a footing? I used it on a hybrid house about 20 years ago, along with open web joists and truss roof, which is uncommon where I am on Long Island (mostly stick frame and wood Is). the Premade foundation was bolted as it was craned into place, no down time to start construction immediately, allowing the house to be completed in a few months
I know a lady that has a 1963 house here in Iowa that the basement walls and floors are made out of wood and still standing.
I love this! Trying to avoid concrete myself on a future build. Are these "slabless slabs" suitable for garages? Can they handle heavy concentrated loads like the weight bearing on car tires? How would you finish the floor for such an application - maybe large-format tile over Schluter-DITRA?
Very interesting concept Steve, being able to not use concrete for the foundation is really intriguing. Please update us regularly on how this works out. How is this tied into the ground by the way to prevent it being lifted up during a storm? Is it just relying on the weight of the building? The Glavel product you showed a while back might also be a good fit for something like this to ensure proper drainage space below the building?
I'm confused about the lack of frost wall - very interested in a frost protected shallow wood foundation - is that what this is? At least that front edge?
My current house was built with a concrete slab, but wood foundation walls for the full basement. Owned it for less than 2 years now, but the basement is warm, dry and seems otherwise no different from any other basement of the 1980s era. Would be curious to get your take on this construction method from an energy usage vs comfort vs cost vs long term reliability. It is not very common construction these days and we did have at least one bank that had reservations when our mortgage broker was hunting for rates. We did some due diligence and found that although some people in general would state to stay clear of them, most of the knowledgeable commentary was that if properly built and maintained to keep water in control said it should last as long as a concrete foundation and would outperform a cinder block foundation. Warm basements in winter and lower energy bills are advantages, along with generally lower building costs.
What about adding a foam on the outside to keep the water and pressure away/further from the wood.
I see it as a workable venture when all the known potential problems are addressed with using wood and I'm sure you are aware of these items.
Is the Halo Subterra taped? Why put it on top of the Stego? What about the warm moist air inside getting cold on the Stego and condensing? Does it have somewhere to go?
I think that i read that the original White House was/is built on a wood foundation along with many other eastern US historical buildings. Also correct me if i'm mistaken but Matt Reisinger built his house on an existing concrete slab and used 2 inches of foam and then double 3/4 plywood for a first-floor subfloor system to account for mechanical systems. I looked at wood basements 20 years ago when we built our forever house, the only drawback was the doubt/uneasiness of the local building department officials although it was code compliant.
Keep pushing the envelope with the new old ideas and new state of the art materials. Modern technology needs to not forget about history and the old school ways.
I know this technique is viable. However, it is cost prohibitive. Something like Superior Walls would cost less and has a thermo break
How was it anchored to the ground?
Does that subterra deter ants or other insects and what tape do you use to connect them? I’ve seen ICF foam pics of ants tunneling through it. It wasn’t Nudura, just basic foam.
I’m curious what you guys used against the foundation for fill. Maybe I missed it. I’m assuming no dirt because of soil expansion and contraction.
He mentioned there is gravel and then a barrier and then the Subterra insulation
Is there anything done to combat uplift? I don't have any trouble imaging that the details in place will keep it dry, but I wonder about high winds or frost heave. Thanks!
Here's an interesting article. S&arch for Wood Foundations - Picasso Does Foundations I'd give a direct link but YT has a habit of deleting comments with such.
Are there any soil or climate zone considerations to understand with this type of foundation?
Will the building slowly creep/slide forward without a heavy, environmentally friendly, concrete, footing, slicing into the Earth? Plants gotta eat.
Steve, i'm sorry to report, all those boats did actually rot away. There are like a handful left in the museums of this world.
On the other hand, all those buildings from that time build with stone, if they survived the bombs of the Second World War, they are still here and kicking!
There’s a difference, boat hulls were designed to get wet, the wood swelling sealed seams of payed caulked timbers, enough said.
If the water table moves up? Would you have problems?
Love it did you use pt studs
would it help to backfill and compact in lifts ?
Why compact? You want water to move through the backfill. Even compacted sand isn't great for water to pass through.
How is the building protected against frost heaving without a frost wall? Or is this in a frost free zone?
Seeing that alma flash is being used it should be in a southern location so I doubt it has much frost heaving.
0:14 he said it's in the midwest somewhere.
I’m curious if GLAVEL would be a good addition or substitute to that wooden foundation??
Glavel is a replacement for gravel, but with some insulation properties. It wouldn't replace any wood. In this situation they could have replaced the gravel and foam with glavel, but glavel is cost-prohibitive in most parts of the country.
I want to know who makes the plywood you are referring too to investigate further before I comment.
It's treated to be PWF plywood.
Sounds like concrete would have been cheaper
but the footing is concrete i assume.....?
Nope, it's gravel. There seems to be anti-concrete vibes in the comments, possibly based on that U.N. scam that grips so many clueless folks.
No concrete. Footing is crushed stone and wood.
Didn’t you also poo-poo wood foundations in a podcast a while back? If so, I give you credit for revisiting the system, but you should probably have a little more patience for the naysayers in the comments.