Insulation Question

[rpmhart333]

I know that we have some mechano-scientifical souls on the forum, so I have a Q. Was reading on the BBC website today about building with Hempcrete (a mix of ground-up hemp, lime, and a binder, which would be stix & brix applicable only) but while they were writing about the thermal qualities of hemp my curiosity was piqued...hemp matting is available online. Would the insulating qualities of it be useful in an RV?
I know it'd trap moisture--which could be remedied--and it might be spendy--that'd be a question for later thought--but the question at hand is would it be efficient? Anyone have any thoughts on the matter?
Thankyew.

 

[eDJ_]

A quick Google Search reveals this information:

The R-value of hempcrete is similar to that of other fibrous insulations, such as straw or cotton, which have an R-value between 2 and 4 per inch. One paper estimates that hempcrete provides an R-value of 2.4 to 4.8 per inch.

Myself, I'd insulate with fiberglass insulation as it would be lighter and
less likely to be a fire hazard.

 

[rpmhart333]

I read the same thing about hempcrete, but recognize it'd be heavy as my Uncle Lewis (and he was not a svelte guy; you could have made about 2.5 regular men out of him). My query was about hemp matting alone, which I recognize would be flammable, but if you have almost any kind of fire in any RV it's unlikely to matter much about the insulation...based on the fires I've seen.
What I was thinking was about the R-value/cost versus other types...as well as ease of installation. I'm not looking forward to that process in my refurb of my class-C.
Thanks for joining in the brainstorming. Hope all's well in SE Ohio.

 

[Spaceman Spiff]

What problem are you trying to solve that traditional insulation won't solve?

Hemp has about the same R-value as fiberglass batts.
Foamular and polyiso have about double the R-value of hemp/fiberglass.
Hemp would be heavier than than the other insulation options.
Foam will not retain water.
The foam insulations would be less likely to attract rodents.
I didn't look up costs.

 

[rruff]

Foamular and polyiso have about double the R-value of hemp/fiberglass.

And not only that, you can use it as a core in a structural sandwich panel and use it to build a "box" to live in. Most efficient when you want to save weight, which is a good idea in anything with wheels and a motor.

 

[maki2]

There is not enough wall thickness in an RV to get much of any R value in an RV. Foam is the lightest in weight and will not absorb water. Also the cost is lower in price. It is pretty much a very simple decision to make to go with foam. There is no way you are going to make a vehicle into an all natural dwelling space. But you can try to do so using as many natural fibers wherever possible if it that is of major importance to you in your lifestyle choices. I myself would never use it under flooring as spills of liquids are going to happen and you do not want any absorbent material that can hold moisture under a floor covering. I even sealed my plywood sub flooring with epoxy and caulked all the edges before installing my foam backed sheet vinyl flooring. It is a 50+ year old fiberglass trailer and some areas of that plywood had gotten rotted out near the door and near a window where the weep hole was clogged. So I had to both repair and then knew I also had to prevent and have a way to take up the floor covering if a large spill should ever happen, which it did. No harm done other than some cleanup time.

If you are in a motor home keeping rodents out means crawling around under the rig making sure there are no voids one could crawl into around the various plumbing tubes, fill any such voids using stainless steel pot scrubber material. Do not use regular steel wool as it can rust.

Another way rodents typically enter, an issue many van owners unintentionally create, is using the magnetic “magic” screens in the doorways. Mice can go right in under those screens as the bottom is not secured. Especially if you leave a step outside right in front of that door. It creates a perfect mouse highway into your home. But few people ever consider that they are not just creating an easy access point for themselves but also for rodents. That type of screening might keep out flies but not rodents. Despite popular belief rodents are active in the daytime as well as at night.

 

[eDJ_]

Although Hempcrete has been certified for residential construction in the USA, I can't imagine it being used in a Van. I don't know how much overall weight it would add to the Van but if it altered the center of gravity it may be an issue.

 

[rruff]

There is not enough wall thickness in an RV to get much of any R value in an RV... There is no way you are going to make a vehicle into an all natural dwelling space. But you can try to do so using as many natural fibers wherever possible if it that is of major importance to you in your lifestyle choices.

Havelock wool is one popular choice. I bet the rodents would absolutely love that! A little insulation can help quite a bit with comfort, but there are tradeoffs. A cab-chassis van or truck with a sandwich panel living space is really ideal.

 

[maki2]

It is not that difficult to prevent rodents from getting into the insulation cavities. Have tight fitting wall boarding with no gaps in it along the edges. Put stainless steel mesh screening over any weep hole drainage areas at the bottom of Van sidewalls. Screen off areas in your engine compartment that lead into the interior of your va. There are YouTube videos showing the susceptible locations in the engine compartment for intrusion. Keep a close eye out for rodent droppings inside of your cabinets or on the floor of your van. Travel with a cat or a breed of dog that loves to hunt rodents. One year I got a mouse in my tow vehicle because when unloading at my campsite I forgot to close my car door for a couple of hours. I discovered it because I noticed some droppings on the floor. I caught it with sticky traps. Later I found its nest with tiny dead newborn babies in it hidden under the center console. Leaving doors open is a very bad idea when camping. If you are in a cargo van without windows and you leave the doors open for ventilation you are substantially increasing your chances of getting rodents inside your van. I know that in such a situation open doors might be essential for heat control so do travel with traps. Actually all nomads should be prepared and carry two sizes of rodent traps for mice and rats.

 

[RonDean]

I helped build a straw bale house once and boy were those walls thick. And then we had to make sure the walls were well sandwiched in plastic sheets to keep the moisture out. I'm thinking hemp would have the same issues. The last thing that occurs to me is hemp might set off a drug sniffing dog.

 

[LargeMarge]

...not...difficult to prevent rodents...Travel with a cat or a breed of dog that loves to hunt rodents...carry two sizes of rodent traps for mice and rats.

.
a)
We have Heelers.
The rig has zero rodents.
.
b)
We use bacon grease on the trap trip.
We handle traps with latex-style disposable gloves to avoid/reduce leaving our scent.
.
c)
For ventilation and light, I mounted 3010 (three feet wide by a foot tall) sliders designed for a stand-still house in our 40' semi-trailer conversion.
Similar to the rig, these are about eight feet above pavement.
We noticed a hole in one screen, initially considered small birds nesting inside.
.
Nope.
.
As I was standing on the ground six feet away looking up at the window-screen, a yuge Black rat climbed out, followed by a second.
Those gymnasts:
* clung to the exterior window frame by their toe-nails, then
* launched onto the roof rail using only upper-body strength, grabbing it with their toe-nails, then, swinging for momentum,
* they flopped up onto the roof, then
* scampered across the roof, then
* dropped onto the porch chain, then
* ran across the deck, then
* jumped a couple feet onto the tire, then
" climbed face-down around the tire,
* and ran into the grass.
.
The entire trip took them about two seconds, plenty of practice.
Several times, each rodent stopped to look me right in the eye standing six feet away.
.
I rarely get angry.
That arrogance pushed my switch to 'furious'.
.
I smeared bacon grease on twenty rat traps, and placed them inside.
Results:
* next morning, seven executed rats.
The kicker:
* each corpse was a fuzzy skeleton.
The survivor(s) cannibalized Uncle Fester and Auntie Morticia.
.
Here is the window and screen pre-vermin:

 

[LargeMarge]

.

...We use bacon grease on the trap trip.
We handle traps with latex-style disposable gloves...
.
I smeared bacon grease on twenty rat traps, and placed them inside.
Results:
* next morning, seven executed rats...

.
re -- bacon grease
.
Wal*Mart has tubs of bacon grease in the cooking oil section.
Adequate for traps, the ingredient list tends to dissuade me from allowing to touch my skin.
.
Consume the stuff?
Probably not.

 

[tactrix]

You guys didn't check out the stats on hempcrete did you? It's fireproof, rot resistant, pest resistant, and hydrophobic. Which means it's THE BEST insulation out there. It decimates all the other ones by a mile. Not to mention it weighs 6-8x less than concrete. So for a small wall insulation like an RV it's actually ideal. It also has great thermal and acoustic properties, which means for any living space it's the best.

 

[rruff]

You guys didn't check out the stats on hempcrete did you?

The PVC foam that I used as a structural core on my walls has 3x the R value of hempcrete, and weighs ~1/10 as much. Hempcrete might be viable for some types of residential construction but it's poor insulator and very heavy compared to other insulation materials.

 

[maki2]

For a typical Van insulation or even in my fiberglass trailer Hempcrete insulation would be unsuitable. There are a number of factors in its properties that tell me that.
First it weighs too much, a whole lot more than a typical insulation foam or batt. Weight really does matter and for me it matters quite a lot as I tow my lightweight fiberglass trailer with a 4 cylinder vehicle. Weight also affects gas mileage so even in a vehicle with a large engine weight matters. It is also too heavy to use overhead to insulate under the roof.

Second it is rigid, no flex to it. Vehicle walls other than in a box van are not flat.

Third it is not easy to cut and other than a box van there will be irregular shapes

Fourth vans have lots of odd shaped crevices and cavities that you could never get a hempcrete board to fill up and that will impact the purpose of having insulation as there will be lots of cold/hot spots.

Lastly for travel on rough roads that material is not suitable. You need something that is flexible or soft or shock absorbing. Hemp does not have those essential properties.

Just because something can be used in a stationary building and is organic does not mean it is an always going to be a good match to use in a different structure made for other purposes. When choosing materials you have to think like an engineer and look at each and every factor involved. Hempcrete does not work for all the factors. It fails to meet a few of the essential ones.

 

[bullfrog !]

8 times less than concrete is still a lot more than rigid foam! Lol!!!

 

[tactrix]

8 times less than concrete is still a lot more than rigid foam! Lol!!!

Yea but foam is a garbage insulator, burns, has a problem with bugs and mold. So maybe take a slight increase in weight for an insulator that protects better in every other way.

 

[tactrix]

A quick Google Search reveals this information:



Myself, I'd insulate with fiberglass insulation as it would be lighter and
less likely to be a fire hazard.

Fiberglass melts, hempcrete doesn't and is fire-resistant. At nearly the same melting point. So I'm sure why you would think that Fiberglass is less of a fire hazard.

 

[tx2sturgis]

tactrix youre new here, I've deleted your post that included hostile remarks towards other valued members here.

Please tone it down a notch. We don't attack members on this forum. You can get your point across without disrespecting others.

Further hostilities will result in removal from the forum.

 

[user 22017]

tactrix youre new here, I've deleted your post that included hostile remarks towards other valued members here.

Please tone it down a notch. We don't attack members on this forum. You can get your point across without disrespecting others.

Further hostilities will result in removal from the forum.

Yet you left (some?) of the comments where members ridiculed a new member. You can explain why he/she is wrong without trying to humiliate them.