The National Fenestration Rating Council is a non-profit organization that developed the uniform rating system used to measure the energy performance of fenestration products. These ratings are standard for all products, regardless of the material they are made of.

R-value is the resistance of heat flow through a given material. The higher the R-Value of a product, the greater resistance it will have to heat flow.

The weep holes may be blocked. Gently clean the weep holes by using a dry paintbrush or vacuum brush attachment to remove any debris. If the weep holes are clear, or if cleaning the weep holes does not result in the removal of the water, contact MI’s Customer Care Department at 717-365-2500 or by email.

MI offers a Limited Lifetime Customer Assurance Warranty on all products. This warranty allows the homeowner to order necessary replacement parts to ensure proper product operation at no charge. Some products also come with a Glass Breakage Limited Warranty. This allows customers to order new replacement glass units at no charge.

Windows do not cause condensation, but excessive humidity levels can. Condensation is a visible evidence of excessive moisture in the air. For more information on condensation, please visit our Product Care page or visit AAMA's website:

If your sash will not stay up, it is likely that your balance is broken or sized improperly. Depending on what type of window you have, the issue will be fixed differently. Visit our video library for information on how to fix and replace broken balances.