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Part Two: Replacement Windows

If you missed Part One of this blog, please click here.

There are some simple DIY things that you can do to help the air leak situation around your windows. One is to simply look for any cracks in the caulk between the surrounding trim and the window unit and between the trim and the adjacent wall and replace it where needed. You can also inspect and repair caulk on the exterior of the house around the windows. This will help some with stopping these leaks. Another other simple DIY method for reducing window air leaks is to install plastic film over the interior of the window and attach it to the wall just outside of the trim and not to the trim itself. Finally, good quality rubber weatherstripping can be used to seal small gaps at the top or bottom of double hung windows. These materials are all inexpensive and can be found at local hardware stores.

The other more fool proof and permanent method of reducing window air leaks is to remove the interior trim that surrounds the windows and seal the leak with an air barrier and then replace the trim and recaulk its outer and inner edges. An air barrier is a material that does not let air pass through it. Cans of low expanding spray foam that you buy at the hardware store are a good option for sealing these gaps. PLEASE NOTE: DO NOT USE regular spray foam- make sure that the can says “low expanding for windows and doors. Other acceptable materials are flexible foam tubing, known as backer rod, with caulk or some other type of sealant, rubber gaskets, or an expanding foam tape product. Do not use fiberglass insulation. This was used for many years in this type of gap and was stuffed in there. Fiberglass is not an air barrier even when property installed. When it is compressed in any way, it does not even make a good insulation material.

So when is it a good idea to replace windows? If you have windows that have broken frames or are broken in other ways that would make it very difficult or too costly to repair them, then you could consider replacing them. If you have single paned windows or windows where the glazing (the putty that holds the glass panels in place) is cracked, it is very possible to have nice storm windows made for the windows and there are people who will come to your house and reglaze windows. There are also experts in our area who will take windows from older homes away and totally restore them; including reglazing, repainting, repairing sashes and even building storm windows. This can often be done for less than or the same cost as purchasing new windows. Heavy old wooden windows may outlast a lot of windows that are on the market today.

If you do decide to replace your windows for aesthetic or other reasons, make sure you ask the contractor to remove the trim around the windows and have him/her do what I just described above. If you do not do this and you thought your windows were drafty before, they may still be drafty after spending thousands of dollars for new windows!

Other things to consider when purchasing new windows are that they should be at least double pane and have low-e coatings. Casement windows are generally more efficient and will have fewer leaking points than double hung windows.

You should also look at the “U-factor” and the Solar Heat Gain coefficient (SHGC) of windows you are considering. The U-factor is the inverse of “R-value”, so to get the R-Value, simply divide the U-Value into 1.  Therefore, the lower the U-factor, the higher the R-Value. The SHGC is a bit tricky. It measures the amount of heat that enters your home through the window glass when the sun is shining. The optimal SHGC for windows in your home depends on what direction the wall where they will reside faces, if you have overhangs or trees shading those windows in the summer, etc… Generally, you want to put higher SHGC (above 0.40) windows on south facing windows as long as they are shaded to some extent in the summer, and lower SHGC (0.35 or less) windows on all of the other sides of the home. Lower SHGC windows are generally also “low-e” coated.

The National Fenestration Research Council (NFRC) rates windows and you should see their label on a sticker on windows and in product literature. For more technical window purchasing information, consider referring to and search under “window glazing.” You can also look for EPA’s ENERGY STAR label on windows and consider this and possible tax incentives for homeowners who use higher quality replacement windows.


By: Helen Reinecke-Wilt

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