VanDweller Community Forums

Full Version: Insulation - Cutting Poly-Iso
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
Pages: 1 2
I've been meticulously documenting my van conversion as a reference tool for others, for them to know what every little step of a conversion really means and whether they might be able to do it.
Currently I'm working on the sub-floor and have just published part three of the installation.
I've been laying poly-iso boards between the ribs of the floor of my Ford Transit.

[Image: cutting-poly-iso.jpg]

You can read about all the details, see photos and view the video here.

Or part 2: Paper Plywood Templates

Or part 1: Tie Downs & Wheel Wells

Enjoy!

Van Williams

Save
Excellent details on your conversion!
Since air gaps are a good thing in insulation, wouldn't it be advantageous (and a lot less work) to just lay the poly-iso in large pieces?
air gaps are good if they are sealed off. if they are not sealed the cold air moves right in. that's why double pane windows must be sealed 100% or they don't work. highdesertranger
(06-17-2016, 06:29 PM)MrNoodly Wrote: [ -> ]Since air gaps are a good thing in insulation, wouldn't it be advantageous (and a lot less work) to just lay the poly-iso in large pieces?


Plus, having unsupported polyIso as the floor probably wouldn't work out too well in the long run...
(06-17-2016, 06:29 PM)MrNoodly Wrote: [ -> ]Since air gaps are a good thing in insulation, wouldn't it be advantageous (and a lot less work) to just lay the poly-iso in large pieces?

Specific to my conversion (Transit LWB MR) where I don't want to compromise full standing height inside the vehicle, I feel that I don't have another 1/2 to 1-1/2 inch to spare to put a layer of insulation on top of the floor.
Filling the spaces between the floor ribs with poly-iso is an attempt to maximize insulation, where more is needed.

Van Williams
I've been following your project for awhile now Van Williams, great work and a nice presentation of the details  When I stumbled across your website I was quite impressed!

This doesn't pertain directly to floor insulation as shown, but as for air gaps being advantageous for insulation as mentioned, there is a small caveat - particularly in vertical air spaces.  If the space is deep enough, a convection current can be set up in the space where air against the warm side of the space begins to rise to the top, and falls back down along the cold surface.  This creates a flow very similar to a heat pipe, and is quite effective at increasing the losses from one side of the space to the other, which is not good.  Insulation materials primarily trap air, restricting or eliminating draft potential by also stopping or restricting this air flow.  These types of materials are usually great at limiting conduction losses.  Radiant barriers need an air gap to be effective, but this is a different can of worms.  Convection currents become an ever larger concern as the temperature difference between the inside and outside surfaces increase, and as the distance between them increases.
(06-18-2016, 04:43 PM)AngryVanMan Wrote: [ -> ]I've been following your project for awhile now Van Williams, great work and a nice presentation of the details  When I stumbled across your website I was quite impressed!

This doesn't pertain directly to floor insulation as shown, but as for air gaps being advantageous for insulation as mentioned, there is a small caveat - particularly in vertical air spaces.  If the space is deep enough, a convection current can be set up in the space where air against the warm side of the space begins to rise to the top, and falls back down along the cold surface.  This creates a flow very similar to a heat pipe, and is quite effective at increasing the losses from one side of the space to the other, which is not good.  Insulation materials primarily trap air, restricting or eliminating draft potential by also stopping or restricting this air flow.  These types of materials are usually great at limiting conduction losses.  Radiant barriers need an air gap to be effective, but this is a different can of worms.  Convection currents become an ever larger concern as the temperature difference between the inside and outside surfaces increase, and as the distance between them increases.

Thanks for your remarks about the website!

I agree about the convection issues. A bit off subject, but relevant: I have always been convinced that more attention should be given to ventilation over insulation. With the inclusion of a floor vent and roof vent, optimal use of natural convection could substantially lower temperatures and humidity inside the vehicle. As you described, natural convection needs a temperature differential, distance between inlet and outlet, height difference. P.S I just finished my somewhat unique floor vent. Will publish that in detail in about a week on my website CargoVanConversion.com

Van Williams
What type of insulation would you recommend that would provide for an air flow between the skin and the inside walls that won't trap moisture and will allow for natural air flow to keep it dry between these two surfaces? Maybe I'm misunderstanding something but I read you need the ventilation but you also need to seal it so it won't ventilate. I'll be in a wide range of humidity and temperatures and want something that will work. The best I can come up with is to allow for airflow between the outer skin of the van and the inner walls of the living area.
(07-14-2016, 07:49 PM)BillTheCat Wrote: [ -> ]What type of insulation would you recommend that would provide for an air flow between the skin and the inside walls that won't trap moisture and will allow for natural air flow to keep it dry between these two surfaces?  Maybe I'm misunderstanding something but I read you need the ventilation but you also need to seal it so it won't ventilate.  I'll be in a wide range of humidity and temperatures and want something that will work.  The best I can come up with is to allow for airflow between the outer skin of the van and the inner  walls of the living area.

IMO there is absolutely no need to worry about providing air flow between the skin of the van and the inner finished wall. Trapping of moisture in there to the point of causing a problem is greatly exaggerated.

There is sometimes a problem with some people who don't provide for good air flow IN the van when using various appliances such as heating water, cooking and using a propane heater.

I cook and heat water with the roof vent wide open, at least one of the upper side windows in the high top open and both the front windows are always cracked to the level of the bottom of the rain guards. I have no moisture build up from the kettle or cooking as long as I do so. Should I try to heat water with less ventilation, then yes, I can see moisture accumulating on the inside of the van (NOT in the wall cavity).

Decide what you want to protect yourself from and plan accordingly. If you want to keep the van cool then consider a radiant heat barrier (coupled of course with DEAD air space). If you need to plan for cold weather then insulate. If you're planning on being where it's virtually a rain forest, then a lot of good air flow IN the van needs to be planned for.
Pages: 1 2