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Let's Get Technical

JM Spider Plus

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Higher Thermal Protection , Higher R values

JM Spider gets an R Value of 4.2 to 4.3 per inch. Higher than wet sprayed cellulose insulation. By achieving high R values per inch JM Spider Custom Insulation System has a high thermal performance, giving you up to an R-15 in 2x4 wall cavities and an R-23 in 2x6 wall cavities. JM Spider will not lose its R-value, even when temperatures are very cold. 

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Better Airflow Resistance

Due to JM's Spider+ finer and more consistent fibers, it gives you  up to 30% better airflow resistance than competitive products. Third party testing shows JM Spider superiority over cellulose product not only on better thermal protection but also better airflow resistance. 


Faster Drying Times

Standard practice is to install JM Spider Plus insulation with 10 percent moisture or less — a lower moisture content than you’ll find in most new wood framing. So, installed as recommended, JM Spider Plus insulation needs no drying time. Once installed, JM Spider dries quickly because the glass fibers cannot absorb and retain moisture.


That means you can put up a vapor retarder or gypsum board without waiting, and without worrying about trapping excessive moisture in the wall, no matter what the humidity or temperature outside.

Wet spray cellulose and other insulation systems similar to JM Spider require a relatively long drying time, and drywall installed too early can significantly increase the chance that trapped moisture will facilitate mold and mildew growth inside the wall. 

Better Sound Control

Johns Manville Spider® insulation sprays in to completely fill all gaps and voids, offering superior coverage. Because of this coverage, it achieves superior sound control, reducing transmission of sound through walls and floor/ceiling assemblies.  JM Spider achieves higher STC ratings than cellulose. Compared with low-density spray foam, the JM Spider-insulated wall outperformed the foam-insulated wall by two STC points.

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Johns Manville Spider® Plus blow-in insulation, now featuring interlocking fiber technology, is the next evolution of the JM insulation family. Interlocking fiber technology allows the fibers to spring and lock into cavities with no adhesive or netting. This means No shrinking, No settling.

Other products settle as fast as 1 day after install

Johns Manville Spider® Plus: No shrinking, No settling.

Even after 4 years and counting*

*Only left 2 pictures 

Faster Installs

Johns Manville Spider® Plus blow-in insulation installs faster than other spray-in systems. JM Spider installs at an average of 2x faster than wet sprayed cellulose and it is faster than using the BIBS system (stapling netting and blowing). JM Spider's faster install combined with its faster drying time enables builders to schedule the next sub-contractor sooner. Which means we can help you stay on schedule and help reduce builder's time on your jobsite, saving you money!

Faster Installs...Faster Drying Times...Move Into Your Home FASTER!!

Naturally Fire Resistant

Fiberglass insulation is made from sand and other inorganic materials  which are melted and then spun into fiber glass. Fiberglass is naturally  noncombustible and remains so for the life of the product. It requires no additional fire-retardant chemical treatments. 

Unfaced fiberglass insulation also is recognized by building code groups as an acceptable fire stop in residential wood frame walls.

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Photos from a Study done by Certainteed Corporation

Not affiliated with Johns Manville

To access the full study please click

Formaldehyde Free


The complete line of JM Formaldehyde-free™ building insulation products has been tested by an independent, nationally recognized laboratory to determine emissions of toxic volatile organic chemicals (VOCs) of concern, including formaldehyde. 

No Formaldehyde, no added chemicals for fire resistance. Safe for you, safe for your family!


Boric acid used in cellulose insulation may be more harmful than you think. Boric acid has been found to meet REACH criteria for classification as toxic for reproduction. In fact a popular brand of cellulose has this on their Safety Data Sheets:

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To access the full study please click on image

JM Spider Plus and all other Johns Manville fiberglass products are free from harmful chemicals. Residential fiberglass insulation is also non carcinogenic . On June 10, 2011, the National Toxicology Program (NTP) removed from its list of “Reasonably Anticipated To Be Carcinogens” biosoluble glass wool fibers used for home and building insulation.

Throughout the years, NAIMA has asserted that “biosoluble” fiber, fiber that readily dissolves in the lungs, is safe to manufacture, install and use when the proper work processes are followed.


Johns Manville did testing and the findings confirmed that  insulation glass fibers dissolve in the lungs relatively quickly, removing any potential for the chronic inflammation that could lead to ill effects on the lungs.

To access reports please click

Competitive Price

While JM Spider+ premium blow-in insulation is not commonly the cheapest insulation option, it is competitively priced. JM Spider is always within reason of cellulose blow in.

The up front cost of JM Spider may be a little more in the beginning but in the long run it will save you more money as it gives you better thermal protection, better airflow resistance, no settling, faster installs which means... faster moving project and safe for you and your family!


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Are you ready for an estimate?

Call (402) 860-4251

or email us at

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