Differences Between Open and Closed Cell Backing Rods

As a rule, smart foam sealant installers, the ones who get the job right, never work aimlessly. They plan ahead. They use decouplers and all manner of accessories to guarantee the best possible results. Backing rods are simply another component in the war against noise. Used to fill expansion joints and cracks, to serve as sealant backstops, the foam inserts come in two different but equally useful forms.

Opting for Open Cell Backing Rods

Right to the heart of the matter, this backstop foam works better indoors. It can be used in sightly damp spaces, but there’s no way this material should ever find its way outdoors. This is a more breathable substance, with its open cells providing a cushioning effect. Due to that key feature, it compresses and contours easily. That means open cell backing rods can squeeze into small cracks and gaps. That’s probably why this product range is such a good companion element, for it squeezes its way into voids that would otherwise trap and perhaps magnify noise vibrations.

Pinpointing the Closed Cell Differences

As a construction material, closed cell backstops are convenient. They have a more robust material backbone, so there’s some strength accompanying the inserts as they’re installed. Moreover, their closed structures are pretty much waterproof, which is a good feature to have on-hand when installing backing rods outdoors. However, there are rare instances in the construction industry when structural strength is not an application-beneficial feature. The noise proofing sector is one such field, unfortunately. It’s here that pliability and open-celled flexibility ensures a tighter fit, one that’ll compress to fill some echo-propagating void.

More on Closed vs. Open Cell Noise Dampening

While it’s true that open bubbles are easier to insert, they’re not always the right solution for a chosen noise-cancelling job. For one thing, because of their tightly woven chambers, closed cells are better low-frequency isolating candidates. If that job was left to an open foam structure, the low-frequency waves would power through the interconnected chambers until they came out the other side. Like floodwater pouring through a cave system, the bass sound wouldn’t be stopped by the interlinked cells. That, quite clearly, is when an installer chooses closed cell backing rods.

Like any other soundproofing assignment, foam compounds and accessory elements can’t be applied haphazardly. That’s no way to carry out such an important task. No, find out what frequencies are causing the most noise pollution. If there are more bass tones penetrating a wall, select closed cell backing rods. If the noise pollution is a few octaves higher, opt for open cell backstops.