Trombe Wall Glass Install

The trombe wall in the front of our house was a classic non-vented passive solar installation. We removed the glass in 2015 because it was in the way when the new windows were installed.

Unglazed Trombe Wall
Unglazed Trombe Wall

This was the second time I tackled installing new (used) glass. Back then I used double sided roofing tape and although it was very sticky it did not hold the glass when the bottom frame slipped off the L brackets and rested on the ground. I was able to shove it back up and support it with 2×2’s and there it stayed until making a final push to LEED certification required that I remove it and finish the installation.

I prepped the wall by repainting all the 2×4 framing with flat black enamel paint. (Low VOC) The second wall had no bottom plate because the original was rotted. I screwed PVC 2×2’s to the bottom of the side 2×4’s and spray painted them black. I had already repaired the membrane where it was torn by regluing it to the cement block with contact cement. Then I washed the membrane with Dawn and warm water.

I had decided to use single pane glass. This was based on research by Peter Ellis who analyzed the data from a New Mexico experiment in the 70’s comparing single pane with double pane results. That study also concluded that non-vented walls performed better than vented walls. The problem with double pane is that the seal between the panes cracks with movement and the glass gets moisture inside. That would cut down on the solar radiance. So I cut apart double pane windows to salvage the single pane safety glass. The glass panes were very dirty from sitting outside. I changed the water and washed them twice. I only worked on one a day and had to pause when the weather was too cold.

The double pane windows were purchased used through Craigslist. The pvc framing was also bought as salvage from Repurposed Materials. It is lattice edging and makes a nice decking as well as framing for quarter inch panels.

My brother suggested that I should use butyl rubber tape instead of double sided roofing tape. In the past it was used to install car windows and it is still used for RV windows. When it came time to try again I ordered several 33’ rolls in a one inch width.

Butyl Putty Tape

I folded most of the tape over to half because the glass had about a half inch overlap on the 2×4 frames.

I also ordered J hooks instead of L brackets.

Squared J hooks

These were stronger than the L brackets I used before and held the bottom frame piece of the window. I had glued the corners of the first frame but the glue was messsy and did not hold up. I did not use any glue the second time I tried the install. I leveled the hooks with the bottom frame screwing them into the board. Then the butyl tape was stuck on the frame and the bottom pvc frame piece laid on the hooks and pressed into the tape.

Construction method to hold glass
Construction method to hold glass

Next I assembled the frame using the double sided glazing tape. I again just used butt joints. I taped the butyl around the 2×4 frame but covered the tape with the protective paper until just before Dave and I could lift the pane and its frame into the bottom frame piece that was secured to the base. Then we just gently pressed the frame into the tape and the windows held!

First panel re-installed
First panel re-installed

I braced the panel overnight while the putty sealed. I found that the openings varied in size across the expanse and sometimes the 2×4’s were not flush so I used shims to level the surface. Later I just used extra folded butyl tape to level gaps. Unfortunately there were two nonstandard sized pieces of glass and both were missing. I’m not sure how I will fill this one under the dining room window.

No horizontal pane
No horizontal pane

I tried to buy a clear lexan multiwall panel to cut for this space but Home Depot pulled white corregated plastic. They said sorry it was misbarcoded! They did not have the lexan. Now I’ll try to order it. I can always return it if they get the wrong item.

In the second spot that was missing a glass pane I am using a 24v solar panel. I bought it through craigslist from a solar installer who resells removed panels. It was almost exactly the right size. But when I tried to put it in place it was 1/8” too tall. So it is installed at a slight angle and is resting on scrap pvc 2×2’s. I want to set up a small solar powered fountain with this panel. It will be easy to remove or replace it if necessary.

Panels installed with solar panel
Window panels with solar panel

The next step is to install trim which is a little tricky with the varying heights, widths and depths of the window frames. I will use as many pvc edges as possible since I have so many.

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