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240 Roof insulation material options

Primergy

Member
Joined
Sep 17, 2007
Location
Snohomish, WA
I'm planning to pull down the headliner in my 240 to run some wires soon.
At the same time I'd like to insulate it a bite before putting back the liner.
What's proven & tested to keep inside temps moderate and maybe also work on cabin noise?
 
I used Dynamat superlite to kill panel vibrations in the 75. I only used where I needed it, so I can't tell you if it made the interior temp drop... (Most likely it did not make any difference in my case).
My car doesn't have tinted windows either, and that is where most of the heat gain comes from. Tint really helps.

Dynamat has an excellent adhesive back, so i would stick it any where. It's pricey, but works well.

Even if you cover the entire interior, The noise will still transmit through all the windows, seals, door seals... etc.
 
I'm planning to pull down the headliner in my 240 to run some wires soon.
At the same time I'd like to insulate it a bite before putting back the liner.
What's proven & tested to keep inside temps moderate and maybe also work on cabin noise?

In my 83 wagon I used some 1/2" polyisocyanurate insulation glued up between the "ribs". I used flexible strips of thin plywood bent slightly to wedge the foam in place until the glue dried. On the wagon, that's a lot of hot metal just above your head when the sun is shining. Total cost about $20.00
 
Yes was thinking about insulation above headliner.. But how to remove the headliner? Started at the tailgate and tried to remove it but after the first foot or so i stopped.. Was doing something wrong.
I have some felt insulation for use in cars. Not that expensive and pretty light even.
 
In my 83 wagon I used some 1/2" polyisocyanurate insulation glued up between the "ribs". I used flexible strips of thin plywood bent slightly to wedge the foam in place until the glue dried. On the wagon, that's a lot of hot metal just above your head when the sun is shining. Total cost about $20.00

How rigid or flexible was that stuff?
Looks like about $10 for a 4 x 8 foot sheet from Home Depot.
Rmax R-Matte Plus-3 1/2 in. x 4 ft. x 8 ft. R-3.2 Polyisocyanurate Rigid Foam Insulation Board
r-matte-foam-board-insulation-754404-64_1000.jpg
 
Rigidity

That's the stuff. Even though it has "rigid" in its name, it will flex enough to fit the gentle curve of the roof. Like corrugated cardboard. The thicker it is, the more rigid. I would stick to 1/2".
 
That Polyisocyanurate is nice! Sure better than cheapo silver-backed bubble wrap with adhesive. Good insulation but will do only very little in terms of sound I imagine.

Also looked into 3M automotive insulation but it costs an arm & a leg!
 
When I was in high school I help a friend of mine cover the floor of his tin can Karmann Ghia with leftover house carpet padding. Closed cell stuff that looks like it's compressed of lots of different colored pieces, about 1/2 inch thick. We glued it down with contact cement. The difference was phenomenal in noise reduction.
Dave B
 
TrafficMaster 3in1 insulation from Home Depot worked great for me. It's thin and pliable, you can glue many layers together using spray adhesive. I redid all floor insulating mats under carpet using 5 layers (to get the same thickness as original fiber mats). DynoMat is great for sound but heavy, while TrafficMaster is very light and effective for temp control.

876-bnp-trafficmaster-underlayment.jpg
 
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TrafficMaster 3in1 insulation from Home Depot worked great for me. It's thin and pliable, you can glue many layers together using spray adhesive. I redid all floor insulating mats under carpet using 5 layers (to get the same thickness as original fiber mats). DynoMat is great for sound but heavy, while TrafficMaster is very light and effective for temp control.

876-bnp-trafficmaster-underlayment.jpg

Tell us how great it was. Did it reduce any temps or sound at all?
 
For sound it worked better than stock floor insulation that's made from some kind of cardboard/pressed fibers stuff (on my 945). 5 layers added up to same thickness so the carpet fits nice over it. I also used couple of layers under all of the the wagon's plywood floor.
 
I'm planning to pull down the headliner in my 240 to run some wires soon.
At the same time I'd like to insulate it a bite before putting back the liner.
What's proven & tested to keep inside temps moderate and maybe also work on cabin noise?

Planning on insulating the roof of my 91 245 sometime too and was interested in seeing what others have done.

I've had what I consider great results on a TB budget using Frost King duct insulation. I got as far as the floors, butt cheeks and rear doors in my 85 245 before I sold it. To my ears it made a huge difference in the sound damping.

In my 91 245 I've gotten as far as the floor from the firewall back to under the rear seats, butt cheeks and inside the rear panels. Also under the hood. What's interesting there is that on the occasionally cool mornings here in Florida where the car is covered in condensation, the insulated hood area remains covered in condensation and you can see the pattern of the under hood bracing (not insulated) after driving for about fifteen minutes.

I really put it there more as a test and it turned out to really help the engine noise and heat insulation and has stayed put without any loss of adhesion.

So I am going to do inside the doors next and unless someone comes up with something else better here, one of these days the roof with the same stuff.

I'm actually surprised it hasn't been mentioned yet. There's quite some videos on the You Tube.

Frost King Duct Insulation
 
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Planning on insulating the roof of my 91 245 sometime too and was interested in seeing what others have done.

I've had what I consider great results on a TB budget using Frost King duct insulation. I got as far as the floors, butt cheeks and rear doors in my 85 245 before I sold it. To my ears it made a huge difference in the sound damping.

In my 91 245 I've gotten as far as the floor from the firewall back to under the rear seats, butt cheeks and inside the rear panels. Also under the hood. What's interesting there is that on the occasionally cool mornings here in Florida where the car is covered in condensation, the insulated hood area remains covered in condensation and you can see the pattern of the under hood bracing (not insulated) after driving for about fifteen minutes.

I really put it there more as a test and it turned out to really help the engine noise and heat insulation and has stayed put without any loss of adhesion.

So I am going to do inside the doors next and unless someone comes up with something else better here, one of these days the roof with the same stuff.

I'm actually surprised it hasn't been mentioned yet. There's quite some videos on the You Tube.

Frost King Duct Insulation

The frost king could be used under the hood? Did you have to use additional adhesive?
 
The frost king could be used under the hood? Did you have to use additional adhesive?

No additional adhesive. It's quite sticky as-is. I did clean under the hood before application and used a foam paint roller on it. It's been there about six months.
 
It became a COVID project...

  • Removed headliner, removed the old, failing anti-rattle tar paper stuff and all leftover glue from it.
  • Replaced that with larger sheets of aluminum backed butyl rubber mats
  • Added two layers of aluminum backed bubble wrap as thermal barrier (with good double sided tape)
  • Added single layer of Thinsulate SM600L for insulation and some noise absorption.
  • Added speaker wire and Canton satellite speakers in the back for an install to come.
  • Added USB wire and dashcam in the front
  • Re-installed headliner with much use of expletives, bending / shaping the metal stringers to conform to the installed bulk of stuff and holding it up there.
Headliner now looks and feels puffy, a bit cloud-like. Noise level in the car is much lower than it was before and my head stayed cooler under the metal roof in the summer.
Now that it's colder out, the interior stays warm for longer.
 
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