Reply
 
Thread Tools Display Modes
 
Old 04-15-2014, 04:33 PM   #1
Junior Member
 
Join Date: Apr 2014
Posts: 21
tyvek???

Been racking my brain and wearing out my google button on the subject of a bulk thermal insulation to use in van walls, side doors, etc.

Fiberglass: cheap limp, sags, breaks down into particulates absorbs moisture

Thinsulate: expensive limp, sags, doesn't break down doesn't absorb moisture

Rockwool: not cheap not limp, doesn't sag, doesn't break down doesn't absorb moisture

Clarifications: Cheap means cheapest practical thing, expensive means most expensive thing I'd consider, not cheap is somewhere in the middle.

Limp, sags, etc means it needs to be attached and supported so it doesn't fall and create gaps or get compacted, which would lower its effectiveness. Breaking down isn't really a concern of mine, as I plan to seal the walls. Read on for an idea that spurred this thread.

Absorbing moisture means it either does or does not hold moisture, lowering its efficiency and causing rust. This moisture comes primarily from respiration and from a warm van in cold weather and a cold van in warm weather.

So here's my idea: use the cheap limp stuff, but structure it in "bags" of Tyvek, a one-way breathable vapor barrier.

The problem I'm trying to solve is that the walls of the van are closed off from it's exterior by steel, which I plan to paint with DIY lizardskin, http://67-72chevytrucks.com/vboard/show ... p?t=511370, then add a sound barrier/isolator/absorber (whatever you want to call it, I'm not being overly technical here) like FatMat, Dynamat, or that cheap roofing ice barrier from Lowe's/Home Depot. To seal this in with Reflectix or some such vapor barrier (an absolute barrier, think ziplock baggy) means there absolutely will be condensation that you hope runs down the wall and out the OE (or additional) drain holes. The vapor barrier does prevent your breath from reaching the exterior walls but it doesn't prevent environmental condensation and I assume anybody converting/insulating a van will condition (heat or cool) its interior. With solid steel on the outside and a solid vapor barrier on the inside, there is no air movement within the walls to dry this condensation, so gravity/the motion of the van are your only hopes of it migrating out. My idea is that a one-way vapor barrier can keep your breath from reaching the walls but can also allow air movement into the wall cavities, thus helping to dry them. So what I'm proposing is a bag, or envelope really, of tyvek that matches a cavities dimensions, plus maybe 2" in each dimension, filled with bulk, un-faced insualtion. The 2" flange around the edges will allow them to be attached to the walls themselves, on the interior side, and prevent the insulation from sagging and also contain their particulates. I think it would be best to adhere the insulation to at least one side of the bag so it doesn't sag within it but I also think slightly compressing the insulation, which might require it be built up in multiple layers in some areas, would help it stay in place, much the same as gluing it in place without stuffing it into cavities as we've all seen done.

Thoughts? Suggestions? Positive or Negative are welcome, I'm here to learn not be patted on the back.
__________________

mwilliamshs is offline   Reply With Quote
Old 04-15-2014, 05:02 PM   #2
Member
 
Join Date: Mar 2014
Posts: 56
Re: tyvek???

Have you looked at this. http://www.homedepot.com/p/UltraTouch-4 ... 5yc1vZbedf
__________________

FastAl is offline   Reply With Quote
Old 04-15-2014, 05:07 PM   #3
Senior Member
 
dhally's Avatar
 
Join Date: Sep 2009
Location: SE Washington
Posts: 801
Garage
Re: tyvek???

I don't think a real vapor barrier is the right idea in a van. It is a very small space and needs to breath or it will get real stuffy real fast. Just stuff the walls full of fiberglass and you're good to go...
__________________
---------------------
2009 E250 RB 5.4L "SilVan"
dhally is offline   Reply With Quote
Old 04-15-2014, 05:17 PM   #4
Junior Member
 
Join Date: Apr 2014
Posts: 21
Re: tyvek???

Quote:
Originally Posted by FastAl
Yeah I've seen it. That looks to me like aluminum foil, an absolute (completely impermeable) vapor barrier, with a highly absorbent insulator (denim? think wet blue jeans) on one side.

What I do not want is an absolute vapor barrier on both sides of a wall. There's already solid steel on one side (the van's exterior) so what I want to prevent condensation, rust, mold, etc is either no vapor barrier on the inside, which seems like it would be bad for insulating efficiency and the humidity of the van, or a one-way vapor barrier that would allow for the movement of air within the van's walls to prevent condensation, but not allow drafts. This would also contain the insulation's fibers, give it more structure to prevent slumping, clumping, etc, and make it more easily removable for service/repairs.

Here's a video demonstrating the properties of Tyvek:


As for just stuffing the walls full of fiberglass, this makes the insulation less effective, and if fiberglass is allowed (or forced) to form tight wads it'll trap moisture and mold, cause rust, etc.
mwilliamshs is offline   Reply With Quote
Old 04-15-2014, 05:27 PM   #5
Member
 
Join Date: Mar 2014
Posts: 56
Re: tyvek???

I hope to see photos and links to what you end up with.
FastAl is offline   Reply With Quote
Old 04-15-2014, 05:34 PM   #6
Junior Member
 
Join Date: Apr 2014
Posts: 21
Re: tyvek???

Maybe phrasing this idea differently or giving an example will help convey the idea.

Your house, assuming it's fairly modern and of the wood-framed variety, probably has siding on the outside, then a one-way vapor barrier, like Tyvek, then wooden sheathing, then wood framing (2x6's or such) then in the bays between the studs fiberglass bats, and if it's faced insulation it'll have kraft paper glued to it's inner edge and that'll be stapled to the interior face of the studs, then you'll have sheet-rock (aka drywall...interesting nomenclature), plaster, etc, that is taped and sealed on edges and in corners, then paint or wallpaper.

I want to simulate this in a van, but in reverse, by necessity. I cannot (or well, really really really don't want to) make the van's exterior water and air permeable except for the existing drain holes at the lower edge of the walls. So, the way to make a breathable wall is to make the interior wall face permeable, preferably in only a single direction, such as with Tyvek.

I'm not suggesting that vans and houses are just a like or that all resident construction techniques and materials are appropriate for van usage but I think the respective variety of damages caused by a sealed wall can be equally damaging, but are actually more easily repaired in a home, in my experience and let's face it, we'd all spend the time and money to repair our houses whereas extreme body rot in our vehicles can be life-ending for them in cost/benefit.
mwilliamshs is offline   Reply With Quote
Old 04-15-2014, 05:37 PM   #7
Member
 
Join Date: Mar 2014
Posts: 56
Re: tyvek???

http://www.bondedlogic.com/construction ... nt-barrier
FastAl is offline   Reply With Quote
Old 04-15-2014, 05:45 PM   #8
Junior Member
 
Join Date: Apr 2014
Posts: 21
top to bottom

Considering the only opening in the steel walls are at their bottoms, I think having opening in the interior walls at their tops makes the most sense for air movement, condensation evaporation, and frankly, construction. Since many van build-outs have shelves around the roof's perimeter for storage, mood lighting, Penthouse attachments, etc, I think what I'll do is build my shelves and end the upper edge of the wall paneling below the roof's edge by maybe a half-inch or possibly running the paneling all the way up and cutting openings in it. The gap(s) will be hidden by the shelves, and will allow natural convection to breathe through the wall cavities. Leaving the drain holes open in the bottom of the walls, and possibly adding some of them, then allowing an air gap between the insulation and the walls (which is needed for radiant barriers anyway), and having the openings at the top of the walls, will allow warm air to move up from below the van, through the wall, and out the top gap(s), then out the back windows (mine pop-out) while underway or via forced ventilation (A/C, fans, etc) while parked or vice-versa (warm air from above but within the van to move down through the wall and out the drain openings. If all the vents, windows, etc are closed in the van, air movement would be non-existent or minimal, because a straw has to be open on both ends for you to blow through it.

Sorry if this is illegible to anyone else and I know it's not much good without pictures, but I'm in the pre-planning stages and mostly writing this out so it makes sense to me. I'm sure I'll end up illustrating this a few times before construction begins. That's why my project is called VanDELAY LOL
mwilliamshs is offline   Reply With Quote
Old 04-15-2014, 05:48 PM   #9
Junior Member
 
Join Date: Apr 2014
Posts: 21
Re: tyvek???

Quote:
Originally Posted by FastAl
http://www.bondedlogic.com/construction-products/ultratouch-radiant-barrier
Another absolute vapor barrier (aluminum foil again) with an absorbent insulator(natural cotton fibers) on it's back side. VERY similar product to the soft-touch denim/foil stuff. NOT what I'm after here. Sealing the wall on both sides is like filling a ziplock baggy with your breath and then putting it in the sun or in the fridge. Condensation city!
mwilliamshs is offline   Reply With Quote
Old 04-15-2014, 05:59 PM   #10
Member
 
Join Date: Mar 2014
Posts: 56
Re: tyvek???

Same stuff. Just provided more info. I put this in my van 6 years ago without any noticeable issues. Of course I have not taken things apart to do any destructive testing.

Don't so quickly dismiss an insulation idea because it does not fit your definition of what you think makes sense. Your assumptions may or may not be correct.
__________________

FastAl is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Sportsmobile SIP or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 02:00 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×