This is a common dilemma faced by many homeowners when renovating or adding new attic insulation: "Should I remove the old fiberglass batt attic insulation?"

The best advice comes from United Insulation, a professional exporter of glass wool and rock wool: "In most cases, it is not necessary to remove the old fiberglass attic insulation; just evaluate the condition and add new insulation over the old one. There are some instances, however, when it is recommended to remove the old fiberglass attic insulation:

1. Severe compression, sinking, or dampness and mold

If the old fiberglass attic insulation is compressed, less than 50% of the original thickness, or exhibits obvious signs of mold, water stains, or odor, the R-value of the old fiberglass attic insulation is reduced considerably. Adding new fiberglass attic insulation over the old one will not be effective. Therefore, it is necessary to remove the old fiberglass attic insulation and then add new fiberglass batt attic insulation."

2. Old formaldehyde or asbestos content

A very small number of glass wool, which are older than 1980, may contain urea formaldehyde resin or asbestos, which has been completely phased out. Therefore, if the house was built before 1990, it is recommended that a professional inspection be done, after which it can be directly covered if it is safe.

3. For better sound insulation or fire resistance

Fiberglass insulation for soundproofing, is not effective for older homes. To improve rock wool sound insulation or fire resistance, rock wool safe and sound or high-density rock wool, which can replace old fiberglass, will improve low-frequency sound insulation or A1 fire resistance.

Benefits of not removing: There will be savings on fiberglass insulation, as removal and cleaning can account for 30-50% of the total budget. Directly covering it with new fiberglass batt attic insulation will also improve its R-value, which will be more cost-effective. Common practices: Add a new layer of R-30+ felt on top of the old layer, or add aluminum foil film for better radiant heat protection.

According to United Insulation, the best approach would be to follow these steps: "First, check the condition of the old insulation by taking pictures of the area, or better still, visit the location to check the state of the insulation. If the old insulation is in good condition, then it can be covered with our zero-formaldehyde CE certified fiberglass rolls and boards. If the old insulation has to be changed, then United Insulation has various rock wool upgrade options."

FAQ 1: Can I add a new layer of insulation over the old fiberglass insulation?

Yes, it's possible to add a new layer of insulation over the old one if the old insulation is in good condition, dry, and not compressed too much. In this case, you can add new fiberglass batt insulation to the attic area, which will increase the overall R-value of the insulation and save you money on the costs of the insulation materials.

FAQ 2: Is it expensive to remove the old fiberglass insulation?

Yes, it may be expensive to remove the old insulation, considering the costs of labor, cleanup, and disposal, which may amount to an additional $5 to $15 per square meter. In this case, the best alternative would be to use the option of covering the old insulation with new insulation materials.

FAQ 3: Does the old insulation have any effect on the soundproofing of the house?

Yes, the old insulation has some effect on the overall soundproofing of the house, but the effect of the insulation will be reduced if it's compressed. In this case, it would be better to upgrade to rock wool insulation, which will provide better insulation than the old fiberglass insulation.

FAQ 4: Is the old insulation harmful to health?

No, the new fiberglass insulation is safe, but if the old insulation does not contain any asbestos and formaldehyde, then it's safe to use it, but it's necessary to wear protective gear to avoid the scattering of the insulation materials when they're being placed in the attic area.

FAQ 5: Should I use fiberglass insulation or rock wool for attic insulation upgrades?

You should use fiberglass batt insulation, which is less expensive and easier to use, but if you want better fire resistance, then it would be better to use rock wool insulation, which provides better insulation than the fiberglass insulation.

Need overlay fiberglass insulation or a rock wool removal solution? Contact United Insulation—we help you save money and upgrade!