Evan Dutch
Well-Known Member
Do you have this insulation installed in a building like mine? Did you use a vapor barrier, and did you cover it with anything after installation?
Keep my garage moisture free
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I admit I did not read all the posts, but back in Missouri where there are millions of "pole buildings", they will use a very thin vapor barrier material before putting down the roof ( under the roo I a trying to say). Thats great if you are putting up a new building!!
Evan Dutch
Well-Known Member
That's the material the metal building supplier offers. The sales rep that I went through told me that its not the best, and if I were to go that route, buy it myself and not through the company since it would be cheaper.
^^ agree ^^ All foams have sizable flame spread ratings, it also gives off acrid smoke when burning. It IS a chemical.
So, it HAS to be covered with sheetrock to achieve a safe fire rating.
Now there's also Rockwool, "safe and sound" batt insulation. Its made from mineral wool and wont burn. But its expensive, about $1 per square foot of surface area.
SAFE'n'SOUND Sound Proof Insulation | ROCKWOOL
Evan Dutch
Well-Known Member
How should I affix the rock wool to the interior walls of my metal building?
rustycowll69
Well-Known Member
No. I bought a house with an existing small(approx 20 x24) pole building/barn. It had fiberglass insulation encapsulated in a fairly heavy vinyl sleeve. It looks like it was inserted prior to metal sheathing installation. Unfortunately the heavy vinyl is not impervious to birds and rodents. so that's not good.
My experience with the rock wool is from restoring a house which I owned,, that had had a fire, which destroyed the kitchen and had extensive smoke damage thruout the rest of the house. That was nearly 10 yrs ago, and I've been very happy with the insulation performance since then.
The batts of Rockwool are sized to fit snugly between wooden wall or floor joists built 16 inches on center.
Not sure about steel construction.
Not sure about steel construction.
Evan Dutch
Well-Known Member
It’s about 24in between the steel tubing
Yea,
What do the steel building salespeople offer for insulation?
What do the steel building salespeople offer for insulation?
Evan Dutch
Well-Known Member
It is a material similar to this, except the one I was offered was either white or somewhat clear, not reflective.
Hmm, R value?
Here is a company that has metal building-specific insulation products.
Bay Insulation Systems | Metal Building Insulation
Bay Insulation Systems | Metal Building Insulation
Here is a build thread a guy here is FL posted and he details his insulation choice.
The cheaper option garage build, 30x40 in NE Florida - The Garage Journal Board
The cheaper option garage build, 30x40 in NE Florida - The Garage Journal Board
Evan Dutch
Well-Known Member
Not sure. I think the option I’m leaning towards is the rock wool with the reflective backing and probably a vapor barrier. The metal framing is actually about 4ft apart. I’m not sure how I’m going to make the insulation stay in place.
MYbe, Thin metal straps screwed in the studs with little self tapping peanut screws?
Phreakish
Well-Known Member
Disclaimer: I'm not anywhere near a building professional, and am barely skilled at building related stuff. But I have done a ton of looking into these things over the past several years as we've remodeled on of our houses and have been working on using our barn for shop activities.
Insulation and sheathing aren't lightweight. Before doing anything I'd ask your building mfg what kind of loads the uprights can take. You may need additional framing (wood or metal) in order to adequately hold up additional mass. The amount of weight that the current framing can hold will determine your available options. Doesn't matter if you can get an r45 wall for $600 if the weight will tear your walls down.
Next, you'll want to know what kind of weight your foundation footer was designed for, because additional framing may help hold more insulation, but if the footer can't take it, then it's moot.
With those constraints sized, you can look at what your feasible options are. How much insulation you need will depend on your goals and climate. R6.5 won't do you much good if you gotta deal with temps under 0, and still may not prevent condensation. Designing an insulated envelope can be tough because you need to constantly keep the interior temperature above the ambient dew point. The more humid your location, the higher the temp needs to remain.
A radiant backing between your metal surface and the backside of your insulation (foil backing) is a good idea. Metal conducts heat quickly and radiates heat much better than wood building materials. You want to ensure that the foil ix permeable though, or that you keep a gap between the back of the insulation and the metal wall so that air can circulate. Even spray foam can absorb water where there are seams and "laps". A good installer can prevent them, but any joints where new spray overlaps cured or partially cured foam can trap water vapor, which becomes standing water.
Since your walls are corrugated, airflow behind the insulation should be easy. The job of your exterior sheathing is basically to keep rain and snow off your insulation, and thats about it. Which means your insulation and any interior sheathing should be sealed to the floor and create one sealed interior envelope. Which also means you want to insulate over the metal beams, not necessarily between them. You can add additional insulation in those cavities, but it will only be marginally effective since any exposed metal will be a point of condensation and will also rob heat from your interior space. If your interior isn't a sealed envelope, warm air will carry water vapor into any place there's an air leak and you'll eventually be dealing with water damage. Even if your materials are waterproof, you may still get mold or bugs, which are no less troublesome. Ants have been known to burrow into foam and even rockwool to make nests. Birds eat ants and like wool-like materials for nests... You can see where this goes.
You can use almost any heat source which vents combustion outside. Direct fired heat sources don't do this, but there's plenty of cheap furnaces or wood heat which will fit the bill. Even an oil burner will do. Just needs to exhaust outside to carry away the moisture. Radiant floor heat is probably one of the best you could install for a shop, but it's typically tough to do after the slab is already poured. Wood fired boilers, heat pump water heaters or any other means of creating heat can be used with it for max efficiency or convenience. You can use electric floor heat, buts it's far less efficient compared to a heat pump driven radiant system.
Polyiso sheets tend to be cheap and if you use two layers (2" ea), staggered. It's possible to get a very tight envelope that should exceed r15 in many cases, which is close to residential requirements in some places. Even rockwool will need sheathing, and probably costs more per square foot than poly iso, and will also require more framing to hold it to the walls since it's made for typical wall cavities (based on what I've seen). Polyiso is also commonly available with a radiant barrier on one side (foil faced) which is still an excellent thing to have in a metal building.
Just my $.02
Insulation and sheathing aren't lightweight. Before doing anything I'd ask your building mfg what kind of loads the uprights can take. You may need additional framing (wood or metal) in order to adequately hold up additional mass. The amount of weight that the current framing can hold will determine your available options. Doesn't matter if you can get an r45 wall for $600 if the weight will tear your walls down.
Next, you'll want to know what kind of weight your foundation footer was designed for, because additional framing may help hold more insulation, but if the footer can't take it, then it's moot.
With those constraints sized, you can look at what your feasible options are. How much insulation you need will depend on your goals and climate. R6.5 won't do you much good if you gotta deal with temps under 0, and still may not prevent condensation. Designing an insulated envelope can be tough because you need to constantly keep the interior temperature above the ambient dew point. The more humid your location, the higher the temp needs to remain.
A radiant backing between your metal surface and the backside of your insulation (foil backing) is a good idea. Metal conducts heat quickly and radiates heat much better than wood building materials. You want to ensure that the foil ix permeable though, or that you keep a gap between the back of the insulation and the metal wall so that air can circulate. Even spray foam can absorb water where there are seams and "laps". A good installer can prevent them, but any joints where new spray overlaps cured or partially cured foam can trap water vapor, which becomes standing water.
Since your walls are corrugated, airflow behind the insulation should be easy. The job of your exterior sheathing is basically to keep rain and snow off your insulation, and thats about it. Which means your insulation and any interior sheathing should be sealed to the floor and create one sealed interior envelope. Which also means you want to insulate over the metal beams, not necessarily between them. You can add additional insulation in those cavities, but it will only be marginally effective since any exposed metal will be a point of condensation and will also rob heat from your interior space. If your interior isn't a sealed envelope, warm air will carry water vapor into any place there's an air leak and you'll eventually be dealing with water damage. Even if your materials are waterproof, you may still get mold or bugs, which are no less troublesome. Ants have been known to burrow into foam and even rockwool to make nests. Birds eat ants and like wool-like materials for nests... You can see where this goes.
You can use almost any heat source which vents combustion outside. Direct fired heat sources don't do this, but there's plenty of cheap furnaces or wood heat which will fit the bill. Even an oil burner will do. Just needs to exhaust outside to carry away the moisture. Radiant floor heat is probably one of the best you could install for a shop, but it's typically tough to do after the slab is already poured. Wood fired boilers, heat pump water heaters or any other means of creating heat can be used with it for max efficiency or convenience. You can use electric floor heat, buts it's far less efficient compared to a heat pump driven radiant system.
Polyiso sheets tend to be cheap and if you use two layers (2" ea), staggered. It's possible to get a very tight envelope that should exceed r15 in many cases, which is close to residential requirements in some places. Even rockwool will need sheathing, and probably costs more per square foot than poly iso, and will also require more framing to hold it to the walls since it's made for typical wall cavities (based on what I've seen). Polyiso is also commonly available with a radiant barrier on one side (foil faced) which is still an excellent thing to have in a metal building.
Just my $.02
Phreakish
Well-Known Member
Roxul makes exterior insulation panels used in commercial construction that comes in 4'x8' sheets. Would be easier to hang than the 14.5x48 peices made to go in wall cavities. Drawback is that big box stores don't carry it, you'll have to order and may have to go through a dealer/distributor to get it.
Evan Dutch
Well-Known Member
Thats a lot of good information. I’m not sure what r value I would need. In my location, the winters may get down to the low teens-upper single digits (quite rare), and the summers will usually be around 100 degrees at the absolute hottest.
rustycowll69
Well-Known Member
I believe Roxul is the brand of rock wool insulation I used. 10yrs ago, it was not well known in the PNW, not sold by Lowes, or Home Despot. I had to go thru a local DIY chain, and special order it. It was a little more expensive, but I thought it was well worth it. It came in different widths, and thicknesses then, and I wouldn't be surprised if it has many more custom applications, now. I used unfaced batts in floor, ceilings, and walls. But I used HD plastic sheeting as vapor barrier over insulation and studs, and beneath sheetrock, with a well ventilated attic. If your furred-out interior wall is just for holding up insulation, and drywall I wouldn't be too worried about structural issues. I mean it's not carrying the roof span load.
An added benefit of insulating the walls that we haven't talked about is noise reduction.
Phreakish
Well-Known Member
I would look at code requirements for wall assemblies. I think R19 is common for places like you describe, but I've never lived there so I have no real clue.
The big criteria is preventing condensation, which is what minimums are based on assuming a "typical" residential heat source. Since it's a garage that's not likely to be cooled and you're not trying to stay at 75F all day, so code minimums should be OK. But when it comes to insulation, more is better.
Doing partial areas, like roof/ceiling will help more in the summer than in winter (but can help prevent drips from condensation). But it really takes doing the whole space to make it right. Including doors.
Phreakish
Well-Known Member
Roxul is the company the makes "Rock wool". But searching Roxul will find the exterior panels faster than the specific product name "Rock wool". They make a ton of awesome stuff and I see new uses on occasion that are pretty cool.
I agree that typical construction wouldn't have any issues holding up sheathing and insulation, but light gauge 2x2 metal isn't the same as typical construction. It's worth checking just to make sure it's not an issue. I'd be most concerned about the increased loading by insulating the ceiling/roof. The walls, not as much, but better safe than sorry.
Evan Dutch
Well-Known Member
Yeah, I would like to do the walls at a minimum, then the roof. The two 10’x10’ garage doors I don’t think I can insulate, since they roll up into themselves.
Phreakish
Well-Known Member
Those are often multiple layers and are a little better than a single skinned door, so I wouldnt sweat it too much. If you add any kind of radiant heat source, point them at the door(s).
You'll want to do ceiling and walls, even if it means adding an "attic" somehow, otherwise the cold roof will still take the heat away and can drip down in your walls.
Polyiso is cheap and light. With the plastic washers on screws used to secure it, it should be easy to put two layers on the ceiling assuming the metal frame can take it (it most likely can, especially if you get little to no snow in the winters). Since polyiso is also flame retardant and it's not a living space, you shouldn't need much if any sheathing. I'd probably furr over the final sheets and then put up a layer of 10-12mil white plastic as a vapor barrier and staple it down nice and tight to give a nice finished surface that bugs won't make nests on. Plus it will keep bugs from getting between the foam sheets as easy. But bare foam would probably also be fine for many years. Polyiso is already white, so you'll get the same light reflecting benefits either way (amazing what white ceiling and walls can do for illumination!).
Evan Dutch
Well-Known Member
It may snow a few inches max every few years or so. What do you mean by furring?
rustycowll69
Well-Known Member
from Google/wikipedia:
In construction, furring (furring strips) are thin strips of wood or other material to level or raise surfaces of another material to prevent dampness, to make space for insulation, or to level and resurface ceilings or walls.Furring refers to the process of installing the strips and to the strips themselves.
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