Closed Cell Or Open Cell Attic

Open cell foam is full of cells that aren t completely encapsulated.

Closed cell or open cell attic.

A spray insulation is referred to open cell or closed cell because of the difference between the small bubbles cells that make up the foam. Closed cell foam for insulation applications range in density from 1 7 lb cu. The higher the density the foam the heavier or stronger it becomes. Open cell foam has an r value of about 3 5 to 3 7 per inch while closed cell foam has an r value of about 6 per inch.

It also will perform better below or above grade. To support traffic and loads better. Closed cell foam is made up of cells that are as the name suggests completely closed. In other words the cells are deliberatly left open.

This makes the foam a softer more flexable material. Closed cell foam can also increase the racking strength of attic walls which. Most insulation contractors are recommending open because it s cheaper and also because if i go with closed cell and the roof leaks it will not penetrate the insulation and could remain stuck between the sheathing and the insulation and could rot the wood and or travel to a more hidden spot of the roof or attic causing worse problems that are harder to notice than if the roof leaked and water penetrated through the open cell which i would be able to see and fix if necessary. On may 26 2018.

Id go with closed cell. Senior editor martin holladay replies. Open cell is more susceptible to mold and mildew but its expanding so it can hermetically seal an area. Open cell foams typically weigh in at 0 4 to 0 5 lb cu.

In unvented roof assemblies open cell foam has been associated with damp roof sheathing and sheathing rot so closed cell foam is usually preferred for this application. Closed cell foam has a higher r value per inch and is vapor impermeable. Seems like you wouldnt want to seal something susceptible to mold growth but maybe thats just me.