The photo above is one window, photographed on one day. The top panes spent years behind solar screens. The bottom panes never had them. Same glass, same house, same weather. The only difference is the screen, and it makes the case about what solar screens do to the glass behind them better than any explanation could.
What a solar screen actually does to the glass
A solar screen is a dense mesh mounted on the outside of the window, a short distance off the glass. It does its main job well. It blocks a large share of the sun before it reaches the pane, which in a Central Texas summer, on west and south facing windows, is a real difference to how hot a room gets.
The problem is the gap between the mesh and the glass. Three things happen in it:
- The rain stops rinsing the window. An exposed window gets washed, a little, every time it rains. A screened one does not, so whatever lands on it stays.
- Dust, pollen and silt still get in. The mesh slows the wind down rather than stopping it, and fine material drops out of the air right there, onto the glass and into the bottom of the frame.
- Moisture gets trapped. Dew, sprinkler mist and humidity get behind the screen and are slow to dry out, because there is little air moving and no sun reaching it.
Put those together for a few years and that gap grows its own ecosystem.
What builds up behind them
On a house in Cedar Park this fall, every one of 20 windows was French pane with a solar screen fixed over it, 407 individual panes in all. When the screens and their hardware came off, behind them was mold, mildew, lime scale, rust and years of silt packed along the bottom of the frames.
It is the same story in other places for different reasons. On the golf course homes at Cimarron Hills in Georgetown, screens go on the back of the house to take golf balls and hail, and what is behind them is usually a dust bowl that needs washing twice. In Bee Cave, construction dust and oak and cedar pollen get caught in the mesh and turn into a gritty paste with the first bit of moisture.
Why it costs more to clean
None of this is a normal clean. The screens have to come down first, and on older installations the hardware fights back. Mold and mineral scale have to be broken down before the glass will come clean at all, and the frames and tracks have to be cleared out, or the silt simply washes back onto the pane. Then the screens themselves need scrubbing before they go back up.
On the Cedar Park house that added up to three to four times the hours of an ordinary 20 window clean, about $800 rather than the $189 minimum. The full breakdown of that job is in what window cleaning actually costs in Austin.
Should you keep your solar screens?
Mason’s own view, after houses like that one, is that he would not put them up. The heat they save is real, but so is what they do to the glass, and most people do not see it until the day the screens come off.
That said, plenty of people have good reasons to keep them, especially on hot west facing rooms and on houses next to a golf course. If you keep them:
- Have them taken down every time the windows are cleaned. Cleaning over a screen cleans the mesh, not the glass.
- Do not leave it years between cleans. The longer the screens stay up, the more of a normal clean turns into a restoration.
- Ask for the screens to be cleaned too. We deep scrub them, then disinfect and deodorize them, because the mesh is where the mildew lives.
- Check the frames and sills while the screens are off. Rust staining and packed silt are much easier to deal with early.
If you are deciding whether to add solar screens to a house that does not have them, it is worth weighing that upkeep against the heat they save, and talking to a few installers about the alternatives before you commit.
Common questions about solar screens
Do solar screens damage windows?
Not directly, but they let damage build up. A screen keeps rain from rinsing the glass, lets dust and silt blow in through the mesh, and holds moisture against the pane. Left for years, that turns into mold, mildew, mineral scale and rust that is far harder to remove than ordinary dirt.
Do you have to remove solar screens to clean windows?
Yes, to clean the glass properly. Cleaning over the screen only cleans the mesh. The screens come down, the glass and frames behind them are cleaned, the screens themselves are scrubbed, and they go back up.
Do you clean the solar screens themselves?
Yes. Screens get a deep scrub, then a disinfecting and deodorizing treatment, before they go back on. That matters with solar screens because the mesh is where the dust, pollen and mildew collect.
Are solar screens worth having in Texas?
They do a real job, cutting heat through west and south facing glass in a Texas summer. The trade off is what builds up behind them. If you keep them, have them taken down whenever the windows are cleaned. If you are deciding whether to add them, weigh that upkeep against the heat they save.
How much more does cleaning behind solar screens cost?
It depends on how long the screens have been up and what is behind them. A house where the screens come down every clean is close to a normal job. A house where they have been up for years can take several times longer. In Cedar Park, 20 French pane windows behind screens came to about $800 rather than the $189 minimum.
The short version
Solar screens keep heat out, and they keep the rain from rinsing your glass. Over a few years the gap behind them fills with dust, silt, moisture, mold and mineral scale. If you keep them, have them taken down at every clean and cleaned themselves. If you are thinking of adding them, know what you are signing up for.