Replacing old windows in my workshop with new energy efficient ones

 

Before and after

Recently I started seeing ads online for replacement windows.  While my home has high-quality Marvin Windows that are double pane, gas-filled, low E very efficient windows my workshop still has the original barn windows whose only purpose was to let light in.  The photo above shows the original window on the left which is entirely made of wood with single pane glass panels.  So I reached out to three different window installer companies to get quotes.

For context, my workshop was originally an open barn built in the early 1990s - so about 35 years old.  When I purchased it in 2001 I converted it into a super insulated very well sealed building using spray in foam and added fiberglass to create R30 walls and R40 roof.  The cheap wood windows have always been the weak point in this building from an energy standpoint but they are also rotting and falling apart so it was time to replace them.

The first company showed up the next day to give me an estimate and they took measurements of all seven windows, 5 on the ground floor and 2 upstairs.  Their first quote was $12,071!  I was stunned!  This was way outside my budget of around $5000 and I told them so.  So I asked them if they could re-quote the job allowing for me to remove all of the trim indoors and outdoors so they could just remove the old windows and put in new ones.  That quote came to $7242, still outside my budget and a big surprise that they could come down that low.  Honestly it struck me as ethically dubious, but still too much for my money.  But these guys kept working the deal like sleazy used car salesman and finally offered another deal of doing three windows for a "mere" $5169.  At this point I got angry and told them to leave.

So then I started researching replacement windows on Lowe's and Home Depot websites and found a window at Lowe's that is a little smaller than the framed opening in my building but, get this - these windows were only $218, so I immediately bought 4 of them because that's all they had in stock at that time.  And they are very high performing windows - see the spec sheet below:

These specs compare favorably with some of the top-of-the-line windows made by Anderson and Marvin.  The whole window is made from vinyl which will never age badly.  

My first step was to remove all the window trim on the outside which was very hard work since the whole building was constructed with BIG nails.  Removing the trim ended up destroying all that wood which was rotting anyway.  Note that I had installed spray foam between the window frame and the window itself because they were huge air gaps there originally.

 The next step was to install flashing tape.  This is 6 inch wide tape with a reflective surface and extremely adhesive rubber that sticks to the walls very well.  After installing a couple of blocking strips I was able to put the window in quite easily: 

 

I then installed the new window using two screws at the top and two at the bottom per the instructions.  I then put a 2 inch wide strip of flashing tape to bridge the window frame to the building and weatherproof it. 

 

 

 

 

I purchased some PVC exterior trim and installed it.  Again, this stuff will never rot like the old wood windows and it looks really great!  It's surprisingly expensive but worth every penny.  One piece of 1X8" 8 feet long cost about $50 and I ripped it down the middle and used that for each window.  I caulked around the outside edges of the trim and also at the bottom edge of the window where it meets the trim using very high quality GE silicone caulk.
 

 

 

 

 

 

 

On the inside.  I forgot to mention that I had to frame the framed opening down to fit the new windows which were 3 inches shorter and 1 inch narrower than the old ones. So I installed a 2 x 8 at the top and bottom and a piece of 3/4" wood on one side to fill in the original framing.

 

 

 

 

 

I was able to reuse a lot of the interior wood trim and then paint it.  I also purchased some primed 1X3 for the final trim framing.  These windows look a lot nicer than the original crappy wooden ones which were natural wood and looking very sad.

 

 

 

 

 

From an energy efficiency standpoint the original 7 windows were costing me approximately $726 a year in heat loss.  The heat loss through the new windows will be around $147, so I improved the window performance by 500%!  My building is heated primarily with a (self installed MrCool) heat pump that is about 400% efficient.  I back that up with a wood stove when it's very cold outside (meaning below 20°F)  and I have a lot of wood scraps both from the demolition work but also as a woodworker I end up with a large amount of scrap anyway.  I use my wood scraps for kindling and burn about one full cord of hardwood per season.

While it was 4 or 5 hours of hard labor to install these windows, it was worth every penny to do it myself and do it the way I wanted it.  I'm not quite done installing them yet but I think my total cost will be less than $2000.  So in a way I'm paying myself thousands of dollars per hour in labor!

I had some trouble locating windows that would fit the upstairs two windows which are slightly smaller so I emailed the manufacturer and asked them if they could make me custom windows.  So far they seem amenable to doing that but I haven't heard back just yet.

Finally, I stripped out the aluminum side rails from the old windows and took them to a local guy who takes scrap metal for recycling, then I took the old window screen and trim scraps to the dump.