Reflective bubble insulation

[Doofy]

Good day to all.

I am new to the forum!


I have a new modular on pilings. The skirting is 2 inch rigid foam insulation in 4 ft pieces, coated in stucco. The gaps are just the textured surfaces touching and maybe up to an 1/8 inch gap. Last year was the first winter. It works well. There were no freezing issues. Coldest was -5, it averages higher, but on a cold day (-30+) with a good wind, there is enough air transfer to drop 5-7 degrees under the house with a few good gusts.

I was thinking the double bubble reflective insulation would be easy to work with. It would create a vapour barrier. Likely be easier to install than a floppy piece of poly and it would offer a reflective surface to reflect light when working under there.

My question is will it offer any real R value over poly?

The skirting is in a channel on a treated 2x4. There will be a 3/4" gap between the bubble insulation and the back side of the skirting. Writing this I wonder if the gap would provide insulation if the back of the skirting was sealed with poly and then the bubble insulation might actually offer some R value.

I was also wondering if I should use acoustic sealant or other goop to seal it to the ground vapour barrier and underside of the home, further stopping drafts. Or, will it react/dissolve? There are 5-7 thermally controlled vents that allow air transfer even when closed (not air tight), so there is no worry of completely sealing off the area if I go to town. Just not sure if other than looking neater, and possible longevity, if there is any benefit of the bubble insulation over poly.

Any experience or thoughts to share?

Thanks!

 

[Doofy]

I was thinking the poly or insulation would be a single layer option, but the above post got me thinking. I read that for real r value the bubble insulation needs an air space. With 3/4 inch air space from concrete, with another 3/4 inch to drywall the bubble insulation offers R7 insulation value.

My skirting is around R10 excluding the drafts. I wonder if the ideal solution would be to seal the channel and use poly to 'seal' the skirting, with a layer of reflective insulation to add a little R-value, a clean finish, and a reflective surface to aid in lighting the area. This would give me around R15 skirting, and the floor of the home is R40

The poly would be stapled with sealant to the front face of the home with the skirting placed against it under a steel channel that allows for heaving and expansion. The bottom side of the skirting fits in a channel and the poly would be sealed to that and stapled to the 2x4 top face. The reflective insulation would then be attached to the bottom of the home and the back face of the 2x4. Possibly sealed to the 2x4 and ground poly.

More trouble than it's worth?

 

[Notch7]

This is mostly a UK forum, your construction methods and terminology are somewhat alien.

Is this part of your house and if so I presume you will have local building codes that will specify thermal values etc.

 

[Doofy]

Ha, well let me speak in earthly terms. My house is a modular. Built in a factory, and shipped to my location. It is completely sealed and self contained and sits on screw piles. 15 foot poles with a helix to screw into teh ground with inserts welded to support the home about 3 feet above ground. It is a high quality version of a mobile home.

The "skirting" is simply to add protection to the plumbing and further insulate the floor from wind. it wraps the perimeter of the home and encloses the crawl space of 3 feet under the house.

I may be wasting my efforts to explain if this is a foreign building style, unless familiar with reflective insulation.

I am not trying to block heat in the summer, just hold heat in the winter. I am trying to verify if double bubble reflective insulation will be of any more value than a layer of plastic vapour barrier. I understand bubble insulation is effective in an attic to reflect heat from the roof, but it seems it may be next to useless in a cooler environment.

 

[jacko555]

Look up the r value https://en.m.wikipedia.org/wiki/R-value_(insulation) of the insulation, then compare it to the r value of plastic vapour barrier. Then contrast this with the r value of traditional insulation.

I suspect higher, however, high enough to make an appreciable / noticeable difference? Guess it depends on where your heat is being lost in winter. If your heat is mostly being lost where you plan to insulate - maybe. If its being lost elsewhere, then it won't make a difference.

 

[Doofy]

That's the hard part. This stuff has an R value of 1.1, but with an air space above it, it has an r value of 15. If you install it in your attic stapled to the rafters it will reflect heat back up and keep your attic 20 degrees cooler.

When you search other uses it gets murky.

 

[oldbutnotdead]

The reflective foil insulation in the UK requires a sizable air gap of static air to achieve its rated R value. Presumably your crawl space needs ventilation (moving air) to prevent condensation so the thermal gain from installing it will be fractional compared with using polythene sheet as a draught excluder.

 

[Doofy]

The reflective foil insulation in the UK requires a sizable air gap of static air to achieve its rated R value. Presumably your crawl space needs ventilation (moving air) to prevent condensation so the thermal gain from installing it will be fractional compared with using polythene sheet as a draught excluder.

As I read more this is what I am understanding. Seems little benefit will be gained for exceptionally higher cost.

It can be used in basements with exterior concrete walls and less air space between wall and drywall, but the R value drops to about 6. There is stagnant air in the air gap of a wall, where I will have a draft likely reducing it to the value of a druaght excluder, as you say. Unless with the example above I could recover that value by sealing with poly first, however there is not much information to be found.

It makes sense to me that it would be much more effective blocking high temperatures, than protecting a 6-8 degree area from -30 chill.