Insulation roof of cabin

[PreppenWolf]

You can also use the bubble wrap to skirt the base and keep wind from under your cabin. I would do this and then cover it with metal roofing panels to protect the wrap.

If you can't crawl under the cabin to install sheets, you can use aluminum HVAC tape to connect sheets, create one huge "blanket", then drag it under the cabin and just staple it on the perimeter.

 

[Scoutmaster]

I can definitely climb underneath and staple this into the rafters… with the vermin and bugs at least this wouldn’t be a massive liability… the cabin is 25x25 feet so it wouldnt be an insane investment. it would be sort of a messy process but very doable.

Wrapping the sides and then installing the metal would also be not super difficult.
Early on I had considered using this method but have focused on structural integrity until now so this might make sense.
I’d need about $800 of it. 6-8 rolls for the underside and 3 for the perimeter. *Using 48 inch by 25 feet. It might be worth the expense.

The big positive would be that it wouldn’t mold or make nice nests for rodents.

 

[wme]

Reflectix works well. It works for 3 main reasons. The r value, its not much (1.1), reflectivity, especially IR and a dead air space.
Installed wrong all you get is R-1.1 done right you can end up with an effective R-21 value.
Go to the factory web sites for correct install procedures. Here is the floor video...https://www.reflectixinc.com/tutorials-and-videos/crawl-space-r-21/

 

[Solarcabin Channel]

I used R19 formaldehyde free insulation between the rafters on my cabin and then 3 inch pine paneling slats over that.

Simple installation and finished the loft for company nicely.

 

[Madcodger]

Reflectix

Installed wrong all you get is R-1.1 done right you can end up with an effective R-21 value.

Huh? What's the magic math at work here? The product does a nice job of reflecting back radiant heat, and if taped properly it can be a decent air barrier. I've used it in a sauna build and other applications and find it useful. But it's not magic, and doesn't magically create resistance to heat transfer equal to 5.5" of mineral wool. Feel free to show your logic and data. I dispute your claim.

 

[wme]

Huh? What's the magic math at work here? The product does a nice job of reflecting back radiant heat, and if taped properly it can be a decent air barrier. I've used it in a sauna build and other applications and find it useful. But it's not magic, and doesn't magically create resistance to heat transfer equal to 5.5" of mineral wool. Feel free to show your logic and data. I dispute your claim.

Did you view the video link I posted?

 

[Supervstech]

Huh? What's the magic math at work here? The product does a nice job of reflecting back radiant heat, and if taped properly it can be a decent air barrier. I've used it in a sauna build and other applications and find it useful. But it's not magic, and doesn't magically create resistance to heat transfer equal to 5.5" of mineral wool. Feel free to show your logic and data. I dispute your claim.

Oh, the claim is legit. Look at the image in the link. Twin air barriers, well sealed internal bat, and lower veil shield. Should work far better than mineral wool.

However… for my money, I would insulate the perimeter of the crawl, and seal the ground exposure. Much better coverage, and home improvement.

 

[Madcodger]

Did you view the video link I posted?

No, because as a reliable construction technique and an insulation product, this has been disproven many times. What you are quoting is what is known as an assembly R-value, not a product R-value. IF (and that's a really big IF) you can repeatedly construct a system of two air-sealed chambers using this product, time after time after time from joist bay to joist bay, you might theoretically achieve R21 as an assembly R-value. But doing so will be extremely difficult if not impossible, which is why federal law (16 CFR 40) has a provision known as the R-value Rule. That rule states that if a manufacturer is making claims that its product is a type of insulation, then the advertised R value must be that of the product alone, and NOT an assembly value. Reflectix has been called out for this type of shenanigans before, including in a 2021 Green Building Advisor article by energy expert Martin Holladay (https://www.greenbuildingadvisor.com/article/a-new-look-at-foil-faced-bubble-wrap).

If you actually believe the advice you are touting, you have yourself been duped. Reflectix has a product R-value of about 1.1 and should not be viewed by anyone as a replacement for a true insulation product that contributes significant R-value, period. As I noted in my previous post, I have personally used the product in situations where I wanted a RADIANT barrier/reflector, and I've even used it with proper taping as an air barrier. But in all those situations I also used a product that has a far better product R-value, as the REAL insulating product. This nonsense has been around for almost as long as bubble wrap itself. But it was nonsense then, and it's nonsense now.

 

[wme]

OK if you say so.

 

[Madcodger]

Oh, the claim is legit. Look at the image in the link. Twin air barriers, well sealed internal bat, and lower veil shield. Should work far better than mineral wool.

It is at best relying on perfect construction techniques that are all but impossible to consistently achieve in the real world. See my reply to the person that posted this long-discredited info above, and any number of articles in respected building science and construction journals, including the link I included. Insulation products are required by federal law to advertise PRODUCT (not assembly) R-values in large part because the perfection required for assembly R-values to exist and be maintained over time are so difficult to achieve. It is important to properly install any insulation product, but the level of skill required for assembly R-values is something far more difficult to achieve, which is why manufacturers cannot legally use those to represent their product (even though many do, as we sadly see).

Also, do the math yourself here. Mineral wool has a PRODUCT R-value of between 4-5 per inch. In a 9.5" cavity space, that's at least R-38 vs. the almost impossible to achieve, alleged R-21 quoted for foil-faced bubble wrap. Not even close, and mineral wool has the advantages of being rodent resistant, fire resistant, not supportive of mold or fungal growth, and retaining most of its resistance to thermal transfer even if it gets wet. Bottom line: Bubble wrap - even when foil faced - is a lousy insulating product, and that has been proven time and time again.

 

[Solarcabin Channel]

It is at best relying on perfect construction techniques that are all but impossible to consistently achieve in the real world. See my reply to the person that posted this long-discredited info above, and any number of articles in respected building science and construction journals, including the link I included. Insulation products are required by federal law to advertise PRODUCT (not assembly) R-values in large part because the perfection required for assembly R-values to exist and be maintained over time are so difficult to achieve. It is important to properly install any insulation product, but the level of skill required for assembly R-values is something far more difficult to achieve, which is why manufacturers cannot legally use those to represent their product (even though mnay do, as we sadly see).

Also, do the math yourself here. Mineral wool has a PRODUCT R-value of between 4-5 per inch. In a 9.5" cavity space, that's at least R-38 vs. the almost impossible to achieve, alleged R-21 quoted for foil-faced bubble wrap. Not even close, and mineral wool has the advantages of being rodent resistant, fire resistant, not supportive of mold or fungal growth, and retaining most of its resistance to thermal transfer even if it gets wet. Bottom line: Bubble wrap - even when foil faced - is a lousy insulating product, and that has been proven time and time again.

"The R-value of double bubble insulation is typically R-3.5 to R-4, depending on the thickness of the insulation. The ICC International Building Code allows you to add additional R-values with trapped air space between the reflective surface of the bubble and the outer wall. Each inch of dead air space is an additional R-5, and the ICC Code allows up to 12 inches, which can add up to an additional R-60."

What is the R-value of double bubble insulation? – Radiant Barrier USA

Not a great insulator but can be an effective radiant barrier.

ADDED: "Dry, absolutely still air has an R-value of 3.6 per inch of air — as good as most insulation materials."

Insulating Your Old House: Part 1

Is your old house drafty in winter, swampy in summer? Almost impossible to heat and cool? That's because when your house was built a half-century or more ago, no one thought insulation was necessary — or, better said, experts believed that the 4" of dead air space inside the stud cavities of...

starcraftcustombuilders.com

 

[Madcodger]

"The R-value of double bubble insulation is typically R-3.5 to R-4, depending on the thickness of the insulation. The ICC International Building Code allows you to add additional R-values with trapped air space between the reflective surface of the bubble and the outer wall. Each inch of dead air space is an additional R-5, and the ICC Code allows up to 12 inches, which can add up to an additional R-60."

What is the R-value of double bubble insulation? – Radiant Barrier USA

Not a great insulator but can be an effective radiant barrier.

1) That source is a sales piece for a radiant barrier company. Just sayin'.
2) One good way to achieve the noted dead air space is by filling that space with an insulation product. Otherwise, relying on perfection in construction and insulation technique makes that a pretty uncertain gamble. Again, there's a reason that assembly R-values are not the R-values an insulation manufacturer is allowed to advertise.
3) Most heat loss in a building is not through radiant transfer (generally less than 10%, and most of that is via windows). Conduction and convection are the big culprits.

Again, bottom line: Use an established, proven material and method for insulating a building. Foil-faced bubble wrap is a bad choice for that need.

 

[Solarcabin Channel]

1) That source is a sales piece for a radiant barrier company. Just sayin'.
2) One good way to achieve the noted dead air space is by filling that space with an insulation product. Otherwise, relying on perfection in construction and insulation technique makes that a pretty uncertain gamble. Again, there's a reason that assembly R-values are not the R-values an insulation manufacturer is allowed to advertise.
3) Most heat loss in a building is not through radiant transfer (generally less than 10%, and most of that is via windows). Conduction and convection are the big culprits.

Again, bottom line: Use an established, proven material and method for insulating a building. Foil-faced bubble wrap is a bad choice for that need.

I'm not arguing and I recommended batt insulation but as a radiant barrier the foil bubble wrap is a good choice.

The way batt insulation works is it traps the air which is why you get no benefit of compressing higher R value batts in to a wall.

Architectural draftsman and had to learn all that stuff many years ago.

 

[Supervstech]

No, because as a reliable construction technique and an insulation product, this has been disproven many times. What you are quoting is what is known as an assembly R-value, not a product R-value. IF (and that's a really big IF) you can repeatedly construct a system of two air-sealed chambers using this product, time after time after time from joist bay to joist bay, you might theoretically achieve R21 as an assembly R-value. But doing so will be extremely difficult if not impossible, which is why federal law (16 CFR 40) has a provision known as the R-value Rule. That rule states that if a manufacturer is making claims that its product is a type of insulation, then the advertised R value must be that of the product alone, and NOT an assembly value. Reflectix has been called out for this type of shenanigans before, including in a 2021 Green Building Advisor article by energy expert Martin Holladay (https://www.greenbuildingadvisor.com/article/a-new-look-at-foil-faced-bubble-wrap).

If you actually believe the advice you are touting, you have yourself been duped. Reflectix has a product R-value of about 1.1 and should not be viewed by anyone as a replacement for a true insulation product that contributes significant R-value, period. As I noted in my previous post, I have personally used the product in situations where I wanted a RADIANT barrier/reflector, and I've even used it with proper taping as an air barrier. But in all those situations I also used a product that has a far better product R-value, as the REAL insulating product. This nonsense has been around for almost as long as bubble wrap itself. But it was nonsense then, and it's nonsense now.

Wait...
Are you assuming that fiberglass or mineral wool has an actual Rvalue? No... it holds air in place that provides the r value... so, any insulation r value is an installed R value. And the bubble wrap may indeed have an R1 r value, but in the R21 installation they are using two layers of it... so it would be R 2 in your mind.

I use a bubble product EXCLUSIVELY in my HVAC business. R8 double layer 1"bubbles. So superior to fiberglass duct wrap...

 

[Madcodger]

Wait...
Are you assuming that fiberglass or mineral wool has an actual Rvalue? No... it holds air in place that provides the r value... so, any insulation r value is an installed R value. And the bubble wrap may indeed have an R1 r value, but in the R21 installation they are using two layers of it... so it would be R 2 in your mind.

I use a bubble product EXCLUSIVELY in my HVAC business. R8 double layer 1"bubbles. So superior to fiberglass duct wrap...

I am very well aware of the way insulation works, including the fact that it is generally the trapped air WITHIN most products that provides the insulating properties. A big problem with what you folks are arguing with these products that quote assembly R-values is that the installation must be done almost perfectly, consistently, to deliver the R-values being tossed around. I haven't seen your work, which I'll assume is of very high quality, but most people don't do that. Reflectix paid a testing company to give them a report (see https://www.reflectixinc.com/wp-content/uploads/T34-ICC-ES-Evaluation-Report-2016-17.pdf) that shows how one can achieve R-6 in duct systems if the complex installation is done perfectly, including the use of 3/4" plastic spacers used to create and maintain a specific air gap. Many HVAC contractors bought into that, but many building science experts did not. I'm going with the latter group, as I've seen the work of far too many of the former.

I think we are at the point in this discussion where we must simply agree to disagree. My hope is that before people go out and buy bubble wrap for any insulation purpose, they research it and other products in respected trade journals and sources other than a forum on the internet or the sales pieces of manufacturers or big box stores. This "debate" in the industry has been going on for much longer than this forum has existed. It obviously continues. I just hope people will look imto it a bit beyond the sponsored lines of an internet search or those influenced by similar paid efforts.

 

[KITROBASKIN]

We use reflectix and understand the limitations.

Have to agree with Madcodger regarding reflectix. Sure there are applications for it.

Consider also degradation of the plastic component over time. Seems like heat (alone) will take a toll but we have seen how sunlight combined with heat will turn it into little bits of plastic/aluminum in a few years.

 

[12VoltInstalls]

You can also use the bubble wrap to skirt the base and keep wind from under your cabin. I would do this and then cover it with metal roofing panels to protect the wrap.

Just do metal roofing or pt plywood. Put the neo-useless reflectix underneath covering over the joist cavities where it will do something useful- OR spray foam/board foam that actually has insulating value. I have done jobs like that: foam cut 1” smaller than the openings, spray can foam the perimeter of each sheet and you are airtight. 3” of foam is ~R15 and while that’s not much the results will be night and day.

 

[Johneb]

great advise thank you ?
I’m leaning toward just sealing interior gaps with chink and seeing how this winter progresses. Just closing obvious gaps should increase heat retention.
Year 1 was brutal… year 2 pretty awesome…and I spent some money this year updating the exterior logs and chink.

It’s super tempting to try to make it into something it isn’t. This is my 3rd winter and this summer I chinked the exterior walls and plugged many holes. Also a new floor and some updated windows. Last winter was beautiful and with the improvements I might not need it. I might need to experience this winter and see how it goes. I might try and seal the side gable walls and see how it performs.
The interior is pretty cool and I don’t want to destroy something that has survived almost 70 years with very minimal maintenance.

I don’t think in 1960 they expected modern snowmobiles, Solar, lithium and generators… modern ski equipment has made a huge difference in how we recreate in the winter. They built this cabin for the July weather not January.

Put an insert w fan in that fireplace. You can find them cheap on Marketplace.

 

[Johneb]

Put an insert w fan in that fireplace. You can find them cheap on Marketplace.

Nevermind. Saw you have one and reason for not using it. Was just skimming posts.

 

[thepartyhound]

I didn't read the whole discussion, so forgive me if this has already been suggested, but THROW ANOTHER LOG ON THE FIRE! Problem solved! If that doesn't do it, get a bigger wood stove! For as little as you are there, the extra wood use wouldn't amount to much.