Need ideas for reinsulating areas of underbelly in Landmark

[jbeletti]

As some are aware, I needed to expose my fresh water and gray 1 tanks for a project I’m working on. In doing so, I removed and discarded the batt insulation that was just above the flex foil insulation. In the case of my fresh water tank insulation, it was a little wet. In the case of the gray 1 tank insulation, it had a lot of construction debris on it. I don’t know why I did - but I tossed it.


So I’m thinking about what insulation I should use to replace what I removed. The tanks are REAL close to the underbelly. Use of anything thicker than a couple of inches will result in super compressed insulation, a bulging underbelly and some difficulty getting the underbelly seamed back together. Not sure what is best - super compressed batts or thinner batts relatively uncompressed.


Unsure if I can find it at my local Lowes, but I see Johns Manville ComfortTherm is fiberglass insulation inside a plastic wrapping. This will make for a less itchful installation and would provide a moisture barrier in case I ever get water in the area again. It comes in an R11 version that is 3.5" thick. That could work if I could find it. It's a special order item at Lowes.



Another thought is to use 1” thick XPS (expanded polystyrene) insulation board (the pink/blue stuff) under the tank and other batting-style in other places.


Does anyone have any thoughts on what I should use, given the minimal thickness requirement and my desire to put in something with some level of moisture resistance?

 

[mlpeloquin]

Jim - when fiberglass is compressed it loosed its ability to insulate. I would go with the pink insulating board under the tank and if there is more room add another layer of the flex foil to fill up the space. The batting is fine everywhere else. Closed cell foam is the best and I think the pink board is closed cell. The closed cell foam board will not allow water in and will not loose its insulating properties if wet.

 

[danemayer]

Jim,

Get 4x8' sheets of foam board, and cut them to the inside width of the frame. Slide one end against the frame and then flex the board slightly to put the other end into place. The board will be held in place by the frame. If there are areas where there's more space available, get attic batting and tape it to the top side of the board before sliding into place.

 

[Silverado23]

Considering fiberglass insulation is useless when wet and the extruded polystyrene insulation has a higher per inch R- value, your better off using the polystyrene sheets.
Another insulation you could consider is additional insulation like reflectix such as http://www.homedepot.com/p/Reflectix-48-in-x-25-ft-Double-Reflective-Insulation-BP48025/100052556 but the R factor is highly variable. Two inches of extruded poly is around R-10 and would not be affected by moisture.

 

[jbeletti]

Hey gang - all great ideas. Thank you!
Wondering how hot the tank heating pad gets? I think I will add a couple inches of water to all tanks, then turn on the Yeti system and take a few IR readings of the fresh water tank heating pad. Just unsure if it's wise to press, say foam board up against it tight - though that's sort of what I want to do with the tank (use 1" board under it).

Behind and on the sides of the tank, I'm thinking of making up my own plastic covered batts by measuring my space, lay sheet plastic on the garage floor, lay out my pieces of cut batting, fold plastic over onto the batts, trim it all carefully and seal it up. In this manner, I will have a fee custom sections of insulation that:
- Won't get wet
- Won't be dusty if I need to get in the area again
- Will be easy to install and if needed, remove

On edit
I spoke to Mike, owner at Ultra Heat, mfr of the tank heating pads we're using. Here's what I learned:

1. The exposed side of the OEM heating pad does not get very hot. Slightly warm to the touch is all. No problem placing foam board up against it
2. There is a bi-metal sensor on the pad where the power wire connects to it. It's best not to crush this spot and if using rigid insulation, make a small cut-out for it
3. I replaced my heating pad as it was installed in a spot on the tank where 1 of the 3 tank straps covered it by about 50%. Mike told me that unless the strap was on the bi-metal component, the strap would not negatively affect the heating pad. He did suggest that a thin layer of rubber or similar protective layer be placed on the strap to protect the heating pad from abrasion

 

[TravelTiger]

Hey gang - all great ideas. Thank you!
Wondering how hot the tank heating pad gets? I think I will add a couple inches of water to all tanks, then turn on the Yeti system and take a few IR readings of the fresh water tank heating pad. Just unsure if it's wise to press, say foam board up against it tight - though that's sort of what I want to do with the tank (use 1" board under it).

Behind and on the sides of the tank, I'm thinking of making up my own plastic covered batts by measuring my space, lay sheet plastic on the garage floor, lay out my pieces of cut batting, fold plastic over onto the batts, trim it all carefully and seal it up. In this manner, I will have a fee custom sections of insulation that:
- Won't get wet
- Won't be dusty if I need to get in the area again
- Will be easy to install and if needed, remove

On edit
I spoke to Mike, owner at Ultra Heat, mfr of the tank heating pads we're using. Here's what I learned:

1. The exposed side of the OEM heating pad does not get very hot. Slightly warm to the touch is all. No problem placing foam board up against it
2. There is a bi-metal sensor on the pad where the power wire connects to it. It's best not to crush this spot and if using rigid insulation, make a small cut-out for it
3. I replaced my heating pad as it was installed in a spot on the tank where 1 of the 3 tank straps covered it by about 50%. Mike told me that unless the strap was on the bi-metal component, the strap would not negatively affect the heating pad. He did suggest that a thin layer of rubber or similar protective layer be placed on the strap to protect the heating pad from abrasion

Thanks for sharing about the Ultraheat pads on tanks.