Insulation brainstorming needed- what did you use and why?

[SassyLass]

I am in the planning stage for the Skoolie that has yet to be purchased. I plan to gut, insulate for a thermal break, and eventually raise the roof. Goal is 4-season full-timer, multiple climates, with winterized everything.

My question for all of you- what brand(s) and type(s) of insulation did you choose for each situation and why? If you can link to the specs even better!

In my research so far, I am finding that many are:
1.) highly flammable and the mfg 'requires' a flame resistant covering such as gypsum board for safety.
-I really don't want to add gypsum- is there an alternative?
-have you found a type/brand that is flame resistant without adding an additional barrier?
2.) several warn about potential wicking and/or absorbing water. This concerns me because of potential condensation when the exterior sheet metal is exposed to the elements- especially within the ribbing that has no thermal break to the exterior.
3.) for all those spray/pour foams that require moisture and air to cure- is that moisture then chemically bonded with the product 100%, or does is always contain moisture that is now in contact with your steel?
4.) pros and cons of foams (spray, HD & LD) especially those that use specialty gases in their manufacture or application process. I see some require an air barrier to prevent off-gassing and degradation of the product/R-value.
5.) shrinkage and expansion - I see many that have up to a 2% variation, and tests that find gaps between sheets caused when expansion damaged the edges with pressure, then cold contracted. This would totally defeat the a thermal bridge.

My concerns about fire safety stem from surviving a fire in a mobile home (started at a wood stove chimney outlet) The fire chief commended my quick emergency reactions, and told me that I only had 18 minutes before it would have been fully engulfed because of the construction materials. He said they didn't expect to find it standing when they arrived- I was 30 minutes from the station.

So- fire safety is very important to me. Been scared sh**less once, dont want to try for twice. I know there is no perfect solution in a skoolie, but I'd like to get as close as possible. What say you all???

 

[nat_ster]

I am in the planning stage for the Skoolie that has yet to be purchased. I plan to gut, insulate for a thermal break, and eventually raise the roof. Goal is 4-season full-timer, multiple climates, with winterized everything.

My question for all of you- what brand(s) and type(s) of insulation did you choose for each situation and why? If you can link to the specs even better!

In my research so far, I am finding that many are:
1.) highly flammable and the mfg 'requires' a flame resistant covering such as gypsum board for safety.

-I really don't want to add gypsum- is there an alternative?
-have you found a type/brand that is flame resistant without adding an additional barrier?

No gypsum is needed. It would be way to heavy. We have fire paints that add burn time.

Paint Specs - PinkShield

Firefree Coatings - Fire Resistant & Fire Retardant Non-Toxic Paints for Building Materials

HOME

2.) several warn about potential wicking and/or absorbing water. This concerns me because of potential condensation when the exterior sheet metal is exposed to the elements- especially within the ribbing that has no thermal break to the exterior.

Closed cell foams do not absorb water. This is not a issue.

3.) for all those spray/pour foams that require moisture and air to cure- is that moisture then chemically bonded with the product 100%, or does is always contain moisture that is now in contact with your steel?

Two part foams you speak of do not need air or water to cure.

Only single part foams in small spray cans like the brand "Great Stuff" need air to dry.

4.) pros and cons of foams (spray, HD & LD) especially those that use specialty gases in their manufacture or application process. I see some require an air barrier to prevent off-gassing and degradation of the product/R-value.

Single part foams that don't dry properly have chemicals that cause steel to rust.

5.) shrinkage and expansion - I see many that have up to a 2% variation, and tests that find gaps between sheets caused when expansion damaged the edges with pressure, then cold contracted. This would totally defeat the a thermal bridge.

This is not a issue. Living full time means full time heated. You won't even notice any difrence.

My concerns about fire safety stem from surviving a fire in a mobile home (started at a wood stove chimney outlet) The fire chief commended my quick emergency reactions, and told me that I only had 18 minutes before it would have been fully engulfed because of the construction materials. He said they didn't expect to find it standing when they arrived- I was 30 minutes from the station.

So- fire safety is very important to me. Been scared sh**less once, dont want to try for twice. I know there is no perfect solution in a skoolie, but I'd like to get as close as possible. What say you all???

What are you concerned about making the fire? Will you have a wood stove?

Strapping (2x4's) are bolted or self tapping #14 screws to the vertical support ribs in the walls.

Cavity behind is filled with spray foam to flush with the surface of the strapping.

Rigid styrofoam is glued to the surface of the strapping. (still inside the bus)

Finish wall covering glues to the rigid styrofoam.

Now, everything on the inside of the bus like cabinets, ect, get screwed through the rigid styrofoam, into the 2x4 strapping.

This way no screw, or bolt from the inside ever touch the steel frame and skin of the bus.

I have 99% of the strapping done on my bus. Pics can be seen here.
http://www.skoolie.net/forums/f11/the-four-season-prime-10138.html

This fellow member also strapped his bus with 1x4's. However, 1x4's split bad. I used 3/4 inch plywood, ripped into 3.5 inch strips, glued two layer together due to the plywood's superiority with holding screws without splitting.
http://www.skoolie.net/forums/f27/armageddon-the-smell-of-airborne-rust-8870.html

I hope this explanation helps.

Nat

Nat

 

[taskswap]

You should make that post your message signature, nat_ster.

 

[juliol]

This has to be the best explanation on insulation, thank you Nat_ster.

J

 

[SassyLass]

Thank you Nat for taking the time to reply. I am very familiar with your method, and that is what prompted my post. I find no flaws in your theory, but I have been having a difficult time finding specific products to use, combine, and appropriate adhesives suitable for the various combinations I contemplate. (Adhesives are destined for another post...)

As I say, I am in research mode, and part of that is comparing available products for cost, quality, and how well they suit my needs. Have you decided on which you will specifically use?

Re: some of your specific answers, I asked them because I found products that DID have those properties, so I was looking for other options.(in particular one (commercial) spray-foam insulation that recommended spraying ceiling joists with water to help curing and adhesion -which will never be on 'my list' btw)

I am working on a phone right now, I will post some of my specific findings when I get to a computer.

Re:wood stove- I would love to include a wood stove. Will I? Remains to be decided. You can bet it will be fire-walled to the nth degree if I do though! ;-)

Some of the other concerns come from various builds I've seen, (which prompted me to look into the properties of the materials used) including replacing fiberglass in an engine cover with a flammable foam, and using a cheap foam with a low melting point on the undercarriage near parts that generate a lot of heat. Somehow using something stamped with "keep from fire and flame" or with temperature restrictions doesn't sit well with me.

I liked the idea of insulating the undercarriage, and realize that it is not a complete thermal break, but looking at the effective R-values of steel beamed constructions, a little is better than nothing I think - If there is a product that can tolerate the heat and moisture. Which, fwiw, I think is highly unlikely. ;-)

 

[SassyLass]

I forgot- Nat- re: "Living full time means full time heated. You won't even notice any difference."

I'm not convinced of this yet. The temperature next to the steel exterior skin in direct sunlight at the peak of summer vs. the temperature of the same spot in the dead of winter is quite considerable. Granted, in your set-up this is spray foam on top and sides, and from what I've found shrinkage/expansion is less than some other products, but still exists. Which specific product would be best?

What about the floor though? Two layers of rigid foam. Cold winter outside of the steel on one side, heated radiant flooring on the other. That can be a big temperature extreme in those (4-6"?).

What about the temperature difference between an air conditioned interior and the surface temps when you use a wood stove?

I don't want to argue any point, I'm just trying to consider and understand the ramifications of all of them.

 

[nat_ster]

Your welcome folks.

I'm in Canada, so the products I have available to me will be different from what you can get.

I have used the white fire paint in the last link on a house I built for a customer. It was a wood finished garage, and the engineer made us paint the stuff on the interior of the entire garage.

The fire paint went on like Elmers white glue. I was told every thick coat was 20 min of burn resistance.

I'm real picky and a perfectionist. I like things just right.
However, the expansion and contraction of the Styrofoam you mention is so little, it's not even a concern for me. The steel the bus is made from will likely expand and contract at close to the same rate as the foam.

Phone your local spray foam contractors and ask them what kind of foam they spray. You only want closed cell, synthetic foams. No open cell, biodegradable types.

The spray foam I use here is done out gassing in 48 hours. 3 pound Closed cell Polyurethane foam is what we use in walls.

More info.
http://en.wikipedia.org/wiki/Spray_foams_%28insulation%29

Nat

 

[SassyLass]

Here is a link with general qualities of different types of insulation. This link is just a general overview, and does not get into specifics by manufacturer.

Insulation Materials | Department of Energy

In particular, and mostly because I have seen these in a build somewhere, I have been comparing properties of:
-Molded expanded polystyrene (MEPS)
-Expanded polystyrene (EPS)
-Extruded polystyrene (XPS)
(Quick fact-EPS and XPS are both made from polystyrene, but EPS is composed of small plastic beads that are fused together and XPS begins as a molten material that is pressed out of a form into sheets. -those damn little beads...)
-Polyiso (polyisocyanurate) - a closed-cell foam that contains a low-conductivity, hydrochlorofluorocarbon-free gas in its cells.
-Polyurethane insulation - available as a liquid sprayed foam, flexible and rigid board - HD closed cell, LD open cell
Soy-based, polyurethane liquid spray-foam

Concerned about weight of this and the oxidation potential with metals:
Cementitious foam costs about as much as polyurethane foam, is nontoxic and nonflammable, and is made from minerals (like magnesium oxide) extracted from seawater.

On the definite NO list so far:
Phenolic foam (phenol-formaldehyde) currently only available as a foamed-in-place insulation - can shrink up to 2% after curing.
Urea-formaldehyde (UF) foam

Is there any other that should be consider in a mobile application?

 

[SassyLass]

Thanks again Nat! I appreciate your time, effort and experience.

 

[nat_ster]

I would not use the rigid, white bead type Styrofoam. It has almost not structural strength, and is less R value.

This is the stuff I use.

Nat

 

[jazty]

Phone your local spray foam contractors and ask them what kind of foam they spray. You only want closed cell, synthetic foams. No open cell, biodegradable types.

I want to re-iterate this: call a professional to do the spray foam!! I wasted money on doing it myself, largely because I wanted the experience (I could have done without the experience). Someone who does it day-in and day-out as their occupation will do a MUCH better job with less waste than a first-time DIYer.

 

[SassyLass]

from Nat_ster-

the expansion and contraction of the Styrofoam you mention is so little, it's not even a concern for me. The steel the bus is made from will likely expand and contract at close to the same rate as the foam.

I found a 'solution'.

From buildingscience.com
"Foam Shrinks, and Other
Lessons: Correction"
11 May 2012 Joseph Lstiburek

http://www.buildingscience.com/docu...rinks-correction/view?searchterm=Foam shrinks

"So what happened...? Foams, all of them, expand and contract due to temperature as do pretty much all materials. Some materials even expand and contract due to moisture changes... when foams are hot they get bigger. When they are cold they get smaller. All of them.

...So, bottom line, all foams move. All of them have joints that open up. All of this can be addressed by using a flexible material to handle the movement at joints or by using multiple layers with offset joints or by a combination of both."

Re:flexible joining material:
"What if you only have one layer of rigid insulation on your walls? Well, nowadays we have tapes and sealants and membrane strips that can withstand the movement. This is a big change over the past twenty years. When I did my barn the first time I tried to deal with the joints with a mastic. That particular mastic did not work. Today, there are all kinds of mastics that can work and in fact do work."

Here is a link to their index of articles including topics like air and water barriers and ventilation etc:

http://www.buildingscience.com/index_html

And the original article. There is a lot of good technical details about construction in here. It is about a retrofit of of a super-insulated barn/office after 16 years. What worked, what failed. Granted, it is based on a stationary building with breathable exteriors, but the details about ant/bug barriers, materials, and building products that lasted (or didn't) is quite informative.

http://www.buildingscience.com/documents/published-articles/pa-foam-shrinks

 

[SassyLass]

Polyiso insulation- r-value decreases with temperature change. Test results here.

For anyone considering Polyiso insulation-

(This information is from the linked article below)

Polyiso Pro - it has one of the highest published R-values per inch.
HOWEVER- the FTC's R-Value rule requires that R-value tests be conducted at a mean temperature of 75°F (23.9°C) and a temperature differential of 50°F (27.8°C). This means that insulation is _usually_ tested with the cold side at 50°F (10°C) and the warm side at 100°F (37.8°C).3

Wouldn't you like to live in a climate with so little temperature variance???

So what happens if you have 2-2" polyiso boards for a 4" total, rated aprox R-24 on your mobile residence which can see 144*F solar heat in summer (apparent R-value decreases by 5) and negative temps in winter (apparent R-value of 4" at 0*F decreases by 7). According to these test results, you will need a more Polyiso to have the same apparent R-value, especially in cold climates. Another solution/suggestion is to use a hybrid insulation approach (I like this idea) - install cold temperature-tolerant insulation on the outside/cold side of the polyiso insulation to increase the mean temperature of the polyiso for maximum R-value effectiveness.

Source- Test results and explanations from Building Science:
Info-502: Temperature Dependence of R-values in Polyisocyanurate Roof Insulation — Building Science Information

 

[taskswap]

I used polyiso to insulate a thermal storage tank for a hot-water storage system on a wood boiler I installed a few years ago. It's very strong - around here, it meets code for roof overlayments (which is important because we can have high snow loads). Strong enough to be the underlayment under a 4'x8'x4' (around 800 gallon) tank full of water without compressing.

However, given my (admittedly limited) experience, I personally wouldn't recommend putting it in a bus. It's rigid almost to a fault, IMO it's harder to cut cleanly than other foams (I found a hacksaw blade worked best) and it absorbs water more than other foams. It might make good flooring, though.

If anybody is REALLY serious about using polyiso, if you're anywhere near the USA-NE area, I know a guy in New Haven, CT that sells this stuff for less than half what you can buy it anywhere else. He buys rejected lots from construction installations - if they get more than a few dings they're not allowed to use it there. He has 1"-4" thicknesses and posts them on Craigslist all the time. It sounds a little back-of-the-truck-ish, but the guy's legit.

 

[nat_ster]

You guys are making my head hurt with all this stuff about expansion and contraction of Styrofoam.

So how much rigid Styrofoam do we need? This is my findings.

Last year late fall I installed my residential foam core entry door. Then I painted it black.

Sun came up one morning, it had been close to freezing that night. Black door was facing the sun.

Within a hour of the sun shining on the door, it was to hot to touch. One more hour later, you could not hold your hand within a inch of the surface of the door.

Back of the door stayed cold for 7 hours before the heat started to bleed through the 1.5 inches of rigid Styrofoam between the two metal surfaces of the door.

9 hours later, the backside of the door was still only only a few degree's warmer than the air temp around me. Then the sun started to set.

So how much rigid Styrofoam insulation do you need? No more than 2 inches by my findings. However 4 inches is always better than 2.

These are the kind of tests I'm interested in. All that other stuff just makes my head hurt.

Nat

 

[SassyLass]

Polyiso insulation

I used polyiso to insulate a thermal storage tank for a hot-water storage system on a wood boiler I installed a few years ago. It's very strong - around here, it meets code for roof overlayments (which is important because we can have high snow loads). Strong enough to be the underlayment under a 4'x8'x4' (around 800 gallon) tank full of water without compressing.

However, given my (admittedly limited) experience, I personally wouldn't recommend putting it in a bus. It's rigid almost to a fault, IMO it's harder to cut cleanly than other foams (I found a hacksaw blade worked best) and it absorbs water more than other foams. It might make good flooring, though.

If anybody is REALLY serious about using polyiso, if you're anywhere near the USA-NE area, I know a guy in New Haven, CT that sells this stuff for less than half what you can buy it anywhere else. He buys rejected lots from construction installations - if they get more than a few dings they're not allowed to use it there. He has 1"-4" thicknesses and posts them on Craigslist all the time. It sounds a little back-of-the-truck-ish, but the guy's legit.

Thanks for sharing your experience tank swap. I will definitely look into that water absorption you mention. Not something I want to add on purpose. The Polyiso has the best published R-value per inch that I've found so far, but I'm still weighing all the other properties too.

 

[SassyLass]

So how much rigid Styrofoam insulation do you need? No more than 2 inches by my findings. However 4 inches is always better than 2.

These are the kind of tests I'm interested in. All that other stuff just makes my head hurt.

They make my head hurt too Nat, but for the life of me, I have been unable to fix my crystal ball and figure out which rigid insulation might be be the best choice, or which one might be inside your door that works so well in high temps. ;-)

I'm just trying to gather and share the facts until I figure out how to fix everyone's crystal ball. <wink>

 

[Scool]

What about spray foam the undercarrage of bus

 

[EastCoastCB]

I want to re-iterate this: call a professional to do the spray foam!! I wasted money on doing it myself, largely because I wanted the experience (I could have done without the experience). Someone who does it day-in and day-out as their occupation will do a MUCH better job with less waste than a first-time DIYer.

Tobeamiss did a bang up job of spray foaming, and spent a fraction of what a "pro" would charge. Dave did his own, too.
The kits aren't too hard to use, and I'll bet the big dollar contractors will eventually either cease to be or have to adjust their egregious pricing.

 

[Greatestrr]

I found a spray foam guy did my bus for $750. Hes in northern illinois