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Old 07-17-2021, 02:40 PM   #1
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Subfloor idea

Has anyone used or thought about using the Dricore R+ one step subfloor and insulation panels in their skoolie. Just saw them at Home Depot. Roughly $8 for a 2x2 panel but by the time you figure total cost on plywood, foam insulation and lumber for the underside of the plywood it is about the same cost.

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Old 07-17-2021, 06:23 PM   #2
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It has very little insulation value - R 1.4, which means it only has about 1/4" foam board. Better than nothing, I suppose, but you still won't be able to handle much in the way of extreme temperatures.
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Old 07-17-2021, 06:36 PM   #3
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It says it has an R value of 3, in a 1 inch product. Is there a better option for higher R value in a small measurement, for those of us trying to save headroom?

https://www.homedepot.com/p/DRICORE-...0003/205505261
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Old 07-17-2021, 06:37 PM   #4
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Mnbusboy thats exactly what I am thinking. Yes it stated r value of 3
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Old 07-17-2021, 07:06 PM   #5
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I just looked at Home Depot
60 of the 2x2 subfloor are $472
8 4x8 sheets each of 1/2" R3 foam insulation and 1/4 inch sanded pine plywood comes to $306

I just looked really quick, I'm sure other components would be required. But it's clearly more expensive.
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Old 07-17-2021, 07:08 PM   #6
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I was also figuring in the lumber needed to build the grid and support the plywood. Osb would be a better choice as it is much stronger than plywood
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Old 07-17-2021, 07:49 PM   #7
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I was looking at this stuff: https://www.homedepot.com/p/DRICORE-...268752#overlay which is 3/4" thick and an R-value of 1.4. R 3 is better than R 1.4 but still not that great.
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Old 07-17-2021, 07:54 PM   #8
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It says it has an R value of 3, in a 1 inch product. Is there a better option for higher R value in a small measurement, for those of us trying to save headroom?
This stuff looks like 1/2" XPS and 1/2" OSB, so really they're rounding up from R2.5 to 3 (XPS is R5 per inch). If you're only willing to lose 1" of headroom on the floor, you would probably do a bit better (and cheaper) to use 3/4" XPS and 5mm underlayment on top of that, although that would feel a bit too squooshy for my tastes.

If I were going to live in a bus in Minnesota, I'd want thicker insulation than that, headroom be damned.
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Old 07-17-2021, 08:55 PM   #9
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About how deep is the existing floor on most buses? Are there insulation options with better R value? How think of plywood is best? I am thinking of doing 2 layers of the 1/2" R3, since that looks like the best R value per inch.
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Old 07-17-2021, 09:16 PM   #10
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XPS foam board has an R-value of 5 per inch. Two layers of 1/2" XPS (@ $15 per sheet X2) will still give you just R-5 (they are rounding 2.5 up to 3 for marketing purposes) but will be a lot more expensive than a single layer of 1" XPS (@ $20 per sheet). After a couple of years, the blower gases used for XPS (which have a lower thermal conductivity than ordinary air) will leech out and be replaced with ordinary air, lowering the R-value to about 4 per inch, about the same as EPS foam board. So arguably, you might as well just start with EPS.

Polyiso board has an R-value of 6.5 per inch, but this is only at 75F. In lower temperatures the R-value drops drastically - it's only R-2 per inch at 15F (these values are from the company's own literature). So this stuff is hideously bad if you're trying to survive cold temperatures, but as good as it gets if your primary concern is surviving hot weather.

Rock wool and fiberglass are worse than any of the boards, about R-3 per inch, and they have effectively no compression resistance.

The best insulating material you could possibly use is aerogel, which is about R-10 per inch. But it's hideously expensive and has no compression resistance whatsoever, so using it for a subfloor would be difficult and costly.

What you use is really just a function of how tall you are and how tall your bus is. My bus is 6'7" from steel floor to the middle of the ceiling and I'm 6'0", so I was able to put 2" XPS on the floor and 3/4" plywood (I'll also have 5mm underlayment and 1/8" vinyl floor planks), and 1.5" XPS between the ribs with 3/4" XPS inside the ribs (along with 5mm underlayment as the ceiling panels). This leaves me with an internal ceiling height of 6'3" - I would say having 2" or 3" over your head is about the bare minimum you'd need to be able to walk comfortably inside your bus, but you could maybe go a little bit less.

6'7" buses seem to be pretty rare - only the high-ceiling Internationals and Thomas C2s have that. Blue Bird high-ceilings are 6'5" and Thomases (other than the C2s) are 6'4", and the short versions of all these buses are really short, like 6'1" or 6'2". This is why roof raises are so common in the skoolie world (I feel very fortunate that I've managed to get away without doing it, but I was prepared to do it if it had proven necessary).
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Old 07-17-2021, 10:26 PM   #11
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Polyiso board has an R-value of 6.5 per inch, but this is only at 75F. In lower temperatures the R-value drops drastically - it's only R-2 per inch at 15F (these values are from the company's own literature). So this stuff is hideously bad if you're trying to survive cold temperatures, but as good as it gets if your primary concern is surviving hot weather.
Do you have any links for this data? Because polyiso is used in freezers and fridges. Also, for the most part, its going to be 75F if you are heating or cooling living space. I don't know anyone who sets their thermostat to 15F
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Old 07-17-2021, 11:13 PM   #12
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My bus is 6' unconverted from floor to ceiling. I'm not sure how thick the flooring or ceiling are, but I'm 5'11" so I don't have much to work with. I was thinking 2 of the 1/2 inches was getting me a little better R factor, but 1 inch will work fine. What's the R value of your floor and ceiling, and how well does it insulate in cold and heat?

The intention is for this bus to be a starter and teach us what we really want in our future dream bus. I just saw an amazing deal and decided it was time to start moving forward with something instead of waiting for nothing.
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Old 07-18-2021, 05:18 AM   #13
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Do you have any links for this data? Because polyiso is used in freezers and fridges. Also, for the most part, its going to be 75F if you are heating or cooling living space. I don't know anyone who sets their thermostat to 15F
http://www.owenscorning.com/NetworkS...h-Bulletin.pdf

The low-R problem is a function of the blower gases used to produce the rigid board, so perhaps for freezer/fridge applications they use different gases. As far as the temperature goes, polyiso board is going to be at a temperature gradient with the inside at near the internal temperature and the outside at near the external temperature, so the overall R-value would be about that of the average temperature between the two extremes. So if it's 15F outside, the R-value would be more like 4 than 2, but still worse than XPS (which improves with colder weather) and that R-value would continue to drop as the temperature drops (obviously up north 15F is nowhere near as cold as it ever gets).
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Old 07-18-2021, 05:52 AM   #14
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My bus is 6' unconverted from floor to ceiling. I'm not sure how thick the flooring or ceiling are, but I'm 5'11" so I don't have much to work with.
Your existing floor will just be 3/4" plywood and rubber matting and ceiling is just going to be the 20 ga. steel headliner, so you're not going to gain more than 1" of headroom after demo.

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What's the R value of your floor and ceiling, and how well does it insulate in cold and heat?
By the stats, my bus should have an R-10 value all around, but much of the XPS was bought used on Craigslist so it's probably more like an R-8 at this point. The bus is very well-insulated for both cold and hot, since I have no steel thermal bridging from outside to inside and a minimum of wood bridging and I have an insulated bulkhead wall separating my interior from the impossible-to-insulate front of the bus.

In weather in the high 20s (F), even with all my windows uninsulated, a 1500-watt electric space heater keeps the interior around 70F. I expect that when I install my 5000 kW diesel air heater and finish up my XPS foam board window inserts (also 2" of XPS) I will be able to be comfortable in much lower temperatures as well. I am planning for the worst Philly weather which very rarely gets as low as 0F.

In hot weather, my bus roof gets to over 130F when it's in direct sunlight, but the temperature of the ceiling inside is only a few degrees above the ambient air temperature when all the windows are open, so it's effective insulation in the heat as well.
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Old 07-18-2021, 07:10 PM   #15
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I just saw this product that claims up to R15 in 1/5". It says it can be used for flooring among other applications. I wonder if I could do 3/4" foam board, then a layer of this on the floor, ceiling, and walls. It would be expensive vs. just foam board, but if it works well it would be worth it.

https://www.amazon.com/gp/aw/d/B08JJ...=AUPN5UGKFOGBP
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Old 07-18-2021, 07:50 PM   #16
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I just saw this product that claims up to R15 in 1/5". It says it can be used for flooring among other applications. I wonder if I could do 3/4" foam board, then a layer of this on the floor, ceiling, and walls. It would be expensive vs. just foam board, but if it works well it would be worth it.

https://www.amazon.com/gp/aw/d/B08JJ...=AUPN5UGKFOGBP
A reflective layer is only useful against radiative heat transfer, and the problem is that at 70F, effectively no heat transfer occurs via radiation - it's almost all due to conduction and convection, which reflective foil is useless against. You would want to have a radiant barrier immediately behind a wood stove, to protect the wall behind it and to reflect heat energy back into your living space, but that's because at 400F or 500F the amount of heat energy being transferred via radiation (as compared to convection and conduction) is enormous (this is ultimately because the amount of radiative heat given off by an object is a function of its absolute temperature taken to the fourth power, so it increases rapidly with increases in temperature, but also decreases rapidly with decreases in temperature).

R-15 is a completely made up number. Normally this kind of material is advertised with an R-3 value, and even that's just an equivalency based on the assumption that the reflective layer is reflecting radiant heat from a sunlit hot roof (150F or higher) and is adjacent to an air gap at least 1" thick. In cold weather or even just normal (non-direct-sunlight) hot weather, it's just a thin layer of foam with approximately an R-1 value.

There aren't any magical solutions to the problem of insulating a living space (except aerogel which is honestly slightly magical).
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Old 07-19-2021, 10:01 PM   #17
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I built down, using L brackets that I attached to the under frame openings, and laid about 1/5” wood paneling in them like a cradle. I added 2” insulation, and filled the gaps with insulating gap filler. Then I laid the 3/4” plywood flooring down over that. That way I didn’t lose any headroom. I think I may have photos of that in my build thread, I’ll check...
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Old 07-24-2021, 05:13 PM   #18
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2003, for our ExpeditionVehicle floor system, we laid sheets of one-inch pink-board directly on the box floor surface.
Over that is half-inch plywood, sealed on all sides and edges.
Visually, we have a bamboo perimeter with slate inserts.
.
Nearly two decades full-time live-aboard, the pink-board shows no sign of deterioration.
I would use this system again.
.
Or I would use a 12v/24v heated floor with complicated controls, then enlarge my bank and the photovoltaic feeding it... with more gizmos to fuss with them.
Trade-offs.
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Old 07-25-2021, 05:43 AM   #19
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Quote:
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XPS foam board has an R-value of 5 per inch. Two layers of 1/2" XPS (@ $15 per sheet X2) will still give you just R-5 (they are rounding 2.5 up to 3 for marketing purposes) but will be a lot more expensive than a single layer of 1" XPS (@ $20 per sheet). After a couple of years, the blower gases used for XPS (which have a lower thermal conductivity than ordinary air) will leech out and be replaced with ordinary air, lowering the R-value to about 4 per inch, about the same as EPS foam board. So arguably, you might as well just start with EPS.

Polyiso board has an R-value of 6.5 per inch, but this is only at 75F. In lower temperatures the R-value drops drastically - it's only R-2 per inch at 15F (these values are from the company's own literature). So this stuff is hideously bad if you're trying to survive cold temperatures, but as good as it gets if your primary concern is surviving hot weather.

Rock wool and fiberglass are worse than any of the boards, about R-3 per inch, and they have effectively no compression resistance.

The best insulating material you could possibly use is aerogel, which is about R-10 per inch. But it's hideously expensive and has no compression resistance whatsoever, so using it for a subfloor would be difficult and costly.

What you use is really just a function of how tall you are and how tall your bus is. My bus is 6'7" from steel floor to the middle of the ceiling and I'm 6'0", so I was able to put 2" XPS on the floor and 3/4" plywood (I'll also have 5mm underlayment and 1/8" vinyl floor planks), and 1.5" XPS between the ribs with 3/4" XPS inside the ribs (along with 5mm underlayment as the ceiling panels). This leaves me with an internal ceiling height of 6'3" - I would say having 2" or 3" over your head is about the bare minimum you'd need to be able to walk comfortably inside your bus, but you could maybe go a little bit less.

6'7" buses seem to be pretty rare - only the high-ceiling Internationals and Thomas C2s have that. Blue Bird high-ceilings are 6'5" and Thomases (other than the C2s) are 6'4", and the short versions of all these buses are really short, like 6'1" or 6'2". This is why roof raises are so common in the skoolie world (I feel very fortunate that I've managed to get away without doing it, but I was prepared to do it if it had proven necessary).

Aren't you missing a few things in your calculations? What is the R value of the OSB? What about the floor covering R values? Wool carpets? Rubber foam? etc.
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Old 07-25-2021, 06:42 AM   #20
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Aren't you missing a few things in your calculations? What is the R value of the OSB? What about the floor covering R values? Wool carpets? Rubber foam? etc.
Wood is about R-1 per inch, so even 3/4" doesn't add much. Rubber is similar and even thinner, typically. Carpet and foam padding are also thin and don't add a whole lot of insulating value.
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