Johns Manville will raise prices on its mechanical, HVAC and industrial insulation by 5% to 12% on Jan. 11, 2027, with its core fiberglass pipe insulation and duct liner taking 10%. The letter to customers, dated Oct. 12, also says JM may limit orders placed ahead of the increase.
Distributor General Insulation posted the announcement the same day. It’s signed by Jamie Karubas, JM’s director of sales for commercial and industrial insulation systems, and goes to every mechanical, HVAC and industrial insulation customer.
Mechanical insulation prices by product line
The biggest increases sit on the products insulation contractors buy most. Per the JM letter:
Pipe insulation, including Micro-Lok HP and HP Ultra, goes up 10%. So do Spin-Glas boards and Micro-Flex, the marine hullboard products and the whole duct liner family, which covers Linacoustic RC, R-300 and Spiracoustic Plus.
Duct board such as SuperDuct RC and Micro-Aire goes up 6%, as does Microlite duct wrap. Zeston PVC fittings and jacketing, ASJ and other facings, and most accessories also take 6%. On the industrial side, Thermo-1200 calcium silicate and the Super Firetemp line rise 6%, and MinWool-1200 mineral wool rises 5%.
The outlier is Saranex film and tape, up 12%.
The ship date sets the price
The increase applies to everything shipped on or after Jan. 11, no matter when the order went in. That’s the clause that matters for estimators. A job bought in November with insulation releasing in February gets the new price unless the material ships first.
JM is also trying to stop a pre-buy rush. The letter says it may review orders placed before the increase and limit quantities based on historical demand and available supply. Contractors who planned to load a warehouse in December should expect pushback.
The letter gives no reason for the increase. That’s typical of these notices, and it leaves buyers guessing whether this is input costs or a supplier pricing into a full order book.
A second insulation increase on the same calendar
This is the second insulation maker to put a January number on the table in two weeks. ROCKWOOL announced a 6% increase effective Jan. 1, stacked on 8% from July. The products differ, since ROCKWOOL is stone wool and most of JM’s mechanical line is fiberglass, but the effect on a mechanical insulation bid is similar.
The timing lines up with where the demand is. Data centers, chip fabs and hospitals carry heavy chilled-water and process piping, and every foot of it needs jacketed pipe insulation. A 10% bump on that line lands hardest on the mechanical insulation subs working those jobs under fixed-price contracts signed months ago.
Insulation is a small slice of a mechanical package. But on a fixed bid, a 10% swing on material that ships in the first quarter comes straight out of the sub’s margin, and the escalation clause is the only thing that moves it back.