Insulation Tape?

[Bandelay1965]

I'm applying pieces of polyiso insulation boards to the ceiing, then taping over the seams between the pieces.


[font=Tahoma, Verdana, Arial, sans-serif]What's the best tape to use for this?[/font]

[font=Tahoma, Verdana, Arial, sans-serif]I started using silver metallic Duck Waterproofing Tape (pic below), but noticed it got WAY colder than the insulation and even colder than the bare fiberglass ceiling (it was about 45F-50F in the van as I worked). So I removed the tape, assuming it's not good to have extremely cold tape strips over insulation meant to keep the van warm. [/font]

[font=Tahoma, Verdana, Arial, sans-serif][img=125x125]https://images-na.ssl-images-amazon.com/images/I/71qH1l4fJvL._AC_SL1200_.jpg[/img][/font][/SIZE]


I've seen others use silver metallic tape for this purpose, but it's either (1) a different material than this Duck Waterproof stuff and doesn't get cold, or (2) it's normal for any tape to get super cold like this Duck tape did, and I overreacted by removing it.

[font=Tahoma, Verdana, Arial, sans-serif]Thanks for any tips.[/font]

 

[maki2]

You are confusing a brand name Duck tape with a product that has been traditionaly used for a specifice purpose, sealing the joints on HVAC ducts. The aluminum foil tape eventually gained the simplified identifier of "duct tape". When you hear people talking it is easy to confuse the sounds of the words duck and duct.

Duct tape works just fine for sealing the joints between the insulation bats. Metal always feels cool to the touch until radiant heat hits it in which case it then feels warmer than the surrounding air. Reflectix insulation, that shiny surface on it is a micro thin coating of aluminum. It does a great job of reflecting radiant heat back towards the heat source. That micro thin coating and the thin duct tape do not make a great heat conductor, they are better at reflecting heat rather than holding onto it.

The thermal dynamics in aluminum and very useful in industrial designs. But it does not just involve only one type of property, it has several ways of being useful.

Thicker pieces of aluminum metal is used as heat sinks that helps draw the heat away from various electronic items to help keep them cool. They put fins into the designs of those heat sinks to help further dissipate the heat out of the aluminum. You can even see that being done in the aluminum non electric fans that people set on top of wood stoves to help distribute heat in the room. https://www.caframolifestylesolutions.com/ecofan/technology/

Of course in the older aluminum windows in houses you can feel the cold temperature coming right through the aluminum frame which is why they now put thermal breaks between an outer frame and an inner frame. But those are thicker pieces of aluminum and the very thin duct tape will not be creating any major issues for you in terms of loss of heat. If the shiny side of the duct tape were exposed to the interior of your van it would reflect a radiant heat source inside your van back towards it. If it was on the exterior side where the sun was shining on it then it would reflect the heat of the sun away from your van. In this case it is the shiny, reflective property that is causing that, not the thickness of the metal since it does not have sufficient thickness to act as a good heat sink, ie conuctor of heat.

 

[Gr8ful]

Tyvek tape for housewrap is what I've always used on poly iso foam bd. seals well & never had a pc of tape come loose.

 

[Bandelay1965]

Thanks for the replies.
Gsfish, it may have been an illusion, but I swear those pieces of tape felt like ice packs!
Maki2, great info, thanks. Always better to know why in addition to what. I do know the difference between generic duct and Duck brand tapes, but can see why you thought I confused the two. Duck does make regular duct tape, but this particular Duck product is waterproofing tape, and is thicker and more rubbery than normal duct tape and the thin aluminum tape...so maybe it does retain and release more of the cold than those kinds? Either way, I think I'll go with Gr8ful's tried-and-true option of Tyvek housewrap tape.

 

[MrNoodly]

In something as small and non-air-tight as a vehicle, the tape you use is unimportant. The differences between them are so minor it doesn't really matter.

 

[Cajunwolf]

I'd have just used a sealant like silicone between the pads leaving the tape out of the picture. It will eventually come falling down with time.

 

[Groovy2]

the Tyvek tape likely good way to go -

3M aluminum Duct tape wont come off its good to 300F -

I used spray Greatstuff foam to glue insulation panels in place -
drys pretty fast - sticks well - easy -