Big Old House Windows - Part 3 in the series

April 15, 2007 by Jeff.

Let’s continue prying into this big old house.  We’re trying to reduce that $500/month gas bill and discuss what’s causing it.  Could it be those big drafty holes called windows?

As with many older houses, these windows are double-hung single pane.  Double-hung means there are two sliding sashes (the moveable parts) – an upper and a lower.  Casement windows are different – they are single sashes hinged on the top, side or bottom and typically operate with a crank.  We’ll leave those for another day.  Single pane means just that – no insulating double panes here.

There are many things we can do to make these windows more energy-efficient.  We start by making sure the putty is in good condition, replace missing sections and seal the glass to the putty with a good coat of exterior paint.

Older windows often use sash cords and weights to counterbalance them and make them easier to open.  The pulley openings let in outside air, and the weight pockets on either side of the window don’t help.  Pullman Manufacturing makes replacements featuring spring-loaded bands instead of ropes and weights.  These units seal the pulley hole and allow stuffing the weight pockets with insulation.  Highly recommended.  Tom Silva on This Old House swears by them, and so do I.  www.pullmanbalances.com 

There are fixed sash picture windows here and there.  Since these don’t operate, we make sure all seams are well caulked and painted, inside and out.  Then we buy some shrink-wrap storm window kits, the kind that mount with tape to the interior window frame.  It shrinks tight when heated with a blow drier and doesn’t look too ugly.  This extra air space adds an insulating cushion to the window, reduces condensation (condensation = rot!) and helps keep out some noise.

I’d like to shrink-wrap all the windows in the house, but we only do picture windows and operable windows in unused rooms.  We trade energy efficiency for the safety of easy exit in the occupied rooms.  Those sashes get sealed around the edges with Mortite – long claylike strips which offer a good temporary seal and won’t get in the way in an emergency.  If you can’t find it locally, these guys have it and lots of other usefull stuff:  www.energyfederation.org  

You may remember that his house has old triple-track storm windows too.  These never seal very well, but reduce wind pressure and protect the inner windows.  We make a quick check to verify that all the storm sashes are clicked in to their tracks and locked tightly where they should be.  You’d be amazed how many are down an inch or two, making them next to useless.

Barring complete replacement, these windows are now as energy efficiency as we can make them.  Next time we’ll move to the attic.  It has zero insulation, which is probably why the house structure is in such good shape.  Confused?  Stay tuned.   

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