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Steel-insulated door for our climate
Sep 23, 2005

 Question: We are looking for a good quality entrance door for our home.   Our existing door is a solid-core wood door and the insulating value is only about R-3.  We were told that a good quality steel door has an insulating value of up to R-15. Have you any information on this type of door?

Answer: A steel-insulated door that is designed to suit our climate that uses impact-resistant insulation and special weatherstripping to keep out cold, snow and moisture is important.

One feature to look for is a wide “thermal break” on the edge of the door between the outside metal skin and the inside skin. Without the thermal break, a transfer of cold from the outside skin may cause frost to form on the hinges or around the edge of the door on the inside.

A quality steel door is made from hot-dipped galvanized steel which has a much higher zinc content than electro-galvanized steel to increases rust resistance, which is important in our harsh climate. The insulation used is high-density urethane and its value is R-15.5.

When installing a new steel door in an existing home, it is necessary to remove the entire jamb and install the new door in its own jamb. A steel door cannot be fitted to an existing out-of-square or irregular jamb. A special sub-sill allows for a better weather seal and provides a better method of attaching the sill to the jamb. Extra long screws can be used to attach the sill to the sub-floor. The sill is made from weather-resistant pine.

Weatherstripping on the door is a magnetic type, which makes a positive weather-tight seal around the door. The threshold weather seal is easy to adjust.

Steel doors come with a primed surface. It is recommended that the door be first lightly sanded with find sandpaper, and then washed down with vinegar and water. Only a high-quality, oil-base paint should be used to finish the door.

Also, choose quality door hardware.  A good dead bolt is a must. If the door has a window in it or there is a window next to the door, the dead bolt should be double keyed, which means that a key is required to open the dead bolt from the outside and the inside, otherwise a burglar could break the glass and unlatch the dead bolt. Make sure that all household members know where the key is in case of fire.