Wool Insulation?

[ReluctantTraveler]

Anyone have any thoughts on Havelock wool insulation?

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I had been planning to frame my DIY camper and use marine-grade plywood + rigid foam sandwich.

but wool batt insulation seems like it would be a much easier installation process, and seems to provide the same R-value and moisture protection at the same thickness as rigid foam.

Is a very attractive option at the moment.

 

[Joe917]

You will get no strength from the wool. It is a viable option for residential building, or even a van where strength is not needed.
A foam core composite panel is very strong, if you are building a shell, foam core is the way to go.
Stick framing and filling in the voids with insulation will give a heavier, weaker, poorer performing system than a well engineered composite build.

 

[ReluctantTraveler]

You will get no strength from the wool. It is a viable option for residential building, or even a van where strength is not needed.

Without a doubt!

I guess my thinking is, for a build where I'm not planning on doing "expedition driving," I'm not sure that matters.

Stick framing and filling in the voids with insulation will give a heavier, weaker, poorer performing system than a well engineered composite build.

Are you sure 2x2 framing filled with batt be heavier than rigid foam and truckloads of SikaFlex? Zero arguments about structural strength.

I imagine it would be at least as strong as "stick and tin" RV construction, though.

 

[ExpoMike]

I had considered the Havelock wool but doing a lot of research, it seems the couple common issues were the smell if it got wet and it tends to compress downward on vertical surfaces when bouncing around on rough roads. I decided to go with Thinsulate which does not have those issues. Ordered from Amazon.

 

[ReluctantTraveler]

I had considered the Havelock wool but doing a lot of research, it seems the couple common issues were the smell if it got wet and it tends to compress downward on vertical surfaces when bouncing around on rough roads. I decided to go with Thinsulate which does not have those issues. Ordered from Amazon.

This is great stuff, thanks! I had seen Thinsulate as a similarly easy to install alternative. Wool has ecofriendly appeal, but it's gotta also do the job!

I wonder if Thinsulate is less likely to slip down because it's glued in? I'm pretty sure the Havelock just gets stuffed, and has no paper backing on it like house batt might. I can absolutely see that compressing over time.

 

[Alloy]

Moisture/condensation in heated/conditioned spaces can be and issue for all types of insulation. For short term RV use (allows the insulation to dry) combined with the location mean it's not usually an issue....until....the use is extended and/or the temp. differntial increases. When this happens there either needs to be enough insulation to keep the dew point outside the heated/conditioned space or the insulation needs to be sealed.

 

[ExpoMike]

This is great stuff, thanks! I had seen Thinsulate as a similarly easy to install alternative. Wool has ecofriendly appeal, but it's gotta also do the job!

I wonder if Thinsulate is less likely to slip down because it's glued in? I'm pretty sure the Havelock just gets stuffed, and has no paper backing on it like house batt might. I can absolutely see that compressing over time.

From what I read, once you glue in Thinsulate, it's not going anywhere. Backing side faces to the inside of the camper, open fibers are what gets glued to the walls. Yeah, the Havelock just gets stuffed in, which is why it will compress/fall over time.

 

[ReluctantTraveler]

Someone else in another forum pointed out that once you stuff it in it probably loses some insulation property since the air in insulation is what provides that.

 

[montechie]

I just started adding Havlock to my OVRLND camper. You don't really "stuff" Havlock wool for the most part, it comes in these 2" thick batts that are not loose wool, kind of "blended", and are just laid into an area. See attached photo of a cut batt. You would only stuff it for really small spaces. You would have to really pack it in to the point of ridiculousness to really loose R-value and that would be in places that other insulations wouldn't fit or would have the same issue. It's been easy to work with, very lightweight, seems lighter than the R-tech foam insulation board I have laying around for the same thickness. You want breathability with wool (or Thinsulate) to take advantage of the insulating material breathability so there's different considerations for covering them than foam board. Foam board doesn't breath so you really need to seal it good to keep moisture getting behind the boards and mildewing.

I'm not trying to convince anyone out of their choice, I decided the wool was an intriguing option I wanted to try it out for myself and was willing to take a flier for a non-toxic lower mildewing choice. I think Thinsulate has many of the similar benefits except no anti-mildew properties but probably with advantages wool doesn't have. Wool is a keratin and doesn't support and can prevent mildew growth. Same reason wool has made such a comeback in endurance sportswear vs synthetics, I've worn the same wool items for many days in horrible conditions without it getting funky. Synthetics have to be specially treated to prevent mildew and bacteria growth.

Not sure about it slipping down, depends on where you're putting it, and how tall of an area and that's easily fixable if it's a concern. I was going to add some form of pins to the taller sections of wall to hold the wool in place, the bats are pretty stiff so don't need much. I don't want to glue anything in regardless of what I do.

For me personally I'll see in a year, I'm in Montana which is fairly low humidity but I 4 season camp so it's going to see lots of weather, and indoor living and cooking. The camper is also on a Jeep Gladiator, so lots of rougher "roads" than the typical RV.

 

[ReluctantTraveler]

I just started adding Havlock to my OVRLND camper. You don't really "stuff" Havlock wool for the most part, it comes in these 2" thick batts that are not loose wool, kind of "blended", and are just laid into an area. See attached photo of a cut batt. You would only stuff it for really small spaces. You would have to really pack it in to the point of ridiculousness to really loose R-value and that would be in places that other insulations wouldn't fit or would have the same issue. It's been easy to work with, very lightweight, seems lighter than the R-tech foam insulation board I have laying around for the same thickness. You want breathability with wool (or Thinsulate) to take advantage of the insulating material breathability so there's different considerations for covering them than foam board. Foam board doesn't breath so you really need to seal it good to keep moisture getting behind the boards and mildewing.

I'm not trying to convince anyone out of their choice, I decided the wool was an intriguing option I wanted to try it out for myself and was willing to take a flier for a non-toxic lower mildewing choice. I think Thinsulate has many of the similar benefits except no anti-mildew properties but probably with advantages wool doesn't have. Wool is a keratin and doesn't support and can prevent mildew growth. Same reason wool has made such a comeback in endurance sportswear vs synthetics, I've worn the same wool items for many days in horrible conditions without it getting funky. Synthetics have to be specially treated to prevent mildew and bacteria growth.

Not sure about it slipping down, depends on where you're putting it, and how tall of an area and that's easily fixable if it's a concern. I was going to add some form of pins to the taller sections of wall to hold the wool in place, the bats are pretty stiff so don't need much. I don't want to glue anything in regardless of what I do.

For me personally I'll see in a year, I'm in Montana which is fairly low humidity but I 4 season camp so it's going to see lots of weather, and indoor living and cooking. The camper is also on a Jeep Gladiator, so lots of rougher "roads" than the typical RV.

View attachment 724704

Thanks for this!

I'll be really curious to hear how things hold up after a year or so. I'm a big fan of wool in other applications as well (socks and shoes, in particular, are amazing in both hot and cool conditions).

 

[Alloy]

I just started adding Havlock to my OVRLND camper. You don't really "stuff" Havlock wool for the most part, it comes in these 2" thick batts that are not loose wool, kind of "blended", and are just laid into an area. See attached photo of a cut batt. You would only stuff it for really small spaces. You would have to really pack it in to the point of ridiculousness to really loose R-value and that would be in places that other insulations wouldn't fit or would have the same issue. It's been easy to work with, very lightweight, seems lighter than the R-tech foam insulation board I have laying around for the same thickness. You want breathability with wool (or Thinsulate) to take advantage of the insulating material breathability so there's different considerations for covering them than foam board. Foam board doesn't breath so you really need to seal it good to keep moisture getting behind the boards and mildewing.

I'm not trying to convince anyone out of their choice, I decided the wool was an intriguing option I wanted to try it out for myself and was willing to take a flier for a non-toxic lower mildewing choice. I think Thinsulate has many of the similar benefits except no anti-mildew properties but probably with advantages wool doesn't have. Wool is a keratin and doesn't support and can prevent mildew growth. Same reason wool has made such a comeback in endurance sportswear vs synthetics, I've worn the same wool items for many days in horrible conditions without it getting funky. Synthetics have to be specially treated to prevent mildew and bacteria growth.

Not sure about it slipping down, depends on where you're putting it, and how tall of an area and that's easily fixable if it's a concern. I was going to add some form of pins to the taller sections of wall to hold the wool in place, the bats are pretty stiff so don't need much. I don't want to glue anything in regardless of what I do.

For me personally I'll see in a year, I'm in Montana which is fairly low humidity but I 4 season camp so it's going to see lots of weather, and indoor living and cooking. The camper is also on a Jeep Gladiator, so lots of rougher "roads" than the typical RV.

View attachment 724704

All my wool clothing sucks up moisture. Drop some of the wool insulation in a bucket of water to see how much water it absorbs. If it turns into a soggy mess like fiberglass matt does I woun't use it.

 

[ReluctantTraveler]

All my wool clothing sucks up moisture. Drop some of the wool insulation in a bucket of water to see how much water it absorbs. If it turns into a soggy mess like fiberglass matt does I woun't use it.

it also releases moisture back into the air and maintains it’s insulative properties when wet. But fair point.

 

[Alloy]

it also releases moisture back into the air and maintains it’s insulative properties when wet. But fair point.

Wool absorbs +/-30% moisture vs. Thinsulate +/-1% vs. Mineral wool that repels moisture.
When hiking my Merino won't dry if it is a lump at the bottom of my pack.
Wool is warm because it holds a layer of warm air next to the skin. I don't know if this is the case with wool insulation in a wall.

 

[ReluctantTraveler]

Wool absorbs +/-30% moisture vs. Thinsulate +/-1% vs. Mineral wool that repels moisture.
When hiking my Merino won't dry if it is a lump at the bottom of my pack.
Wool is warm because it holds a layer of warm air next to the skin. I don't know if this is the case with wool insulation in a wall.

That's true... I'd assume wool needs proper ventilation (and dry conditions) to actually evaporate out its moisture, meaning in humid situations, wool insulation would likely hold onto water in your walls. Which, thinking about... eek!

 

[montechie]

When hiking my Merino won't dry if it is a lump at the bottom of my pack.

That's why you wouldn't use a vapor barrier with wool (or Thinsulate). Any material won't dry out in the bottom of your pack, most packs act like a vapor barrier and aren't breathable, although wool will develop less to no mildew compared to the other options and prevent your pack from mildewing as well. I've certainly made that mistake and have smelled the results. ? A piece of foam board in a wet pack would also be bad and show what happens when moisture gets behind vapor barriers. That's wool's strength though, controlled moisture management (keeps it away from other surfaces) combined with mildew/mold prevention. I also probably wouldn't use wool in the Southeast US, but you're going to get moisture inside any wall, especially many DIY vapor barriers using any tape. If you can panel (not basic plywood) and properly caulk, that would probably be the superior option for both R-value and moisture build-up. I'm interested in how wool does in a moderately humid environment like the PNW which I spend a lot of time in year-around. I'm also going to use a breathable, but water resistant layer over my insulation to trap air, slow down moisture absorption, and then help with drying things out.

Wool is warm because it holds a layer of warm air next to the skin. I don't know if this is the case with wool insulation in a wall.

Wool, as well as things like Polar Fleece keep you warm (wet or dry) because they trap air in the material itself, not just next to the skin, and don't collapse when soggy. All insulation works this way to some extent, the combination of the material being insulative (prevent energy transfer) and trapping air. Some don't work when wet, the material collapses (bird down for example) and the airspace disappears. Wool's "crimp" or waviness helps with this and polar fleece mimics crimp. Thinsulate is also supposed to also still insulate when wet, I've had mixed results with it in my backcountry gear vs polar fleece or wool, but that's when saturated. ?‍♂️

Mineral wool could be an intriguing option, but I would be wary of the majority of the materials (glass & silicate fibers) it's made out of in a small living space. I wonder how bad the silicate versions are? Would be very fire resistant I imagine.

Going through my old notes, the unique negatives of wool, specifically Havelock to consider are:

• Smell, if it doesn't smell when new it was chemically washed and there are +/- to not having lanolin in the wool.
• Moths, they go after natural fibers. Some wool insulation is chemically treated to prevent pests from wanting to eat the natural fiber. Havlock doesn't do this, but lanolin should repell insects so it's a trade off for the smell.
• Cost.