January 14th, 2008

How To Tuesday: Install Solar Tube Lighting

Posted by Dan Sharp

Looking for a simple project to green your home? Installing a solar tube light is an easy one-day job and can be done with basic tools if you have a typical shingle roof.  A solar tube provides light like a skylight, but doesn’t require major structural changes to the roof of your house.

You can purchase a solar tube kit for $200 to $400 at most hardware stores or you can find them here at Low Impact Living.  There are several sizes which refer to the diameter of the reflective tube that brings light down into the room.  A 10” version will provide light for about 100 square feet. A 13” option is available if you need to light a larger area, up to 250 square feet.  Larger tubes are available, but require structural modifications and are more difficult to install.

We decided to install a small solar tube in our upstairs bathroom, which is the only room in our house with inadequate natural light.  I’m not usually excited about reading instructions, but it was necessary for this project. The instructions were so thorough, that it would be easy to lose track of the overall steps. For any job, it’s helpful to have an understanding of the big picture before you get into the nitty-gritty. Here are the main steps involved in the installation, and some tips you may find useful.

1. Reconnaissance

The first step in the installation process is to go on a recon mission in the attic. The reflective tube needs to go down from the roof to the ceiling of the room and avoid electrical wires, plumbing, heating ducts, and other obstacles. It fits in between the roof rafters and ceiling joists so find a spot you think will work and have an assistant verify that it looks like a good spot for the room you’re trying to light.

2. Cut the holes

Next you need to identify the spot on the roof directly above the hole you’re planning on putting in the ceiling.  Then draw a circle the size of your tube to make sure it will fit between the joists and rafters.  Once you’re sure it will fit, drill a small hole in the center of the circle down into the room and out to the roof.  Now, you can finally leave the attic!  From inside the room, center a circle the size of your tube on the hole you just drilled and cut it out using a drywall saw.  Then go on the roof and do the same thing…this time, you’ll need a reciprocating saw or jigsaw.  Make sure to keep the saw blade vertical (not perpendicular to the roof).  This will allow your tube to be installed vertically. 

3. Assemble and insert the tube

Be sure to check the instructions for this part, but you probably need to connect a couple lengths of tube together and attach a dome to the top.  Determine how long it needs to be and cut it to the correct length.  Now just slide the tube into the hole.  You may need to modify the holes slightly to get it to fit.  Once you know it fits, set it to the side for a minute. 

4. Weather Proofing   

A large-diameter roof jack provides the seal between the roof and the solar tube.  You’ll need to peel back and trim a couple layers of shingles and slide the roof jack underneath them.  Make sure to put a generous amount of roof sealant on the roof jack, but do NOT put sealant on the lowest edge which allows it to drain if water happens to get underneath it.  Next, slide the completed solar tube into the roof jack and down into the room.  Check the instructions to see how far it should extend into the room and attach the tube to the roof jack with sheet metal screws.  You will also need to nail the roof jack down and attach a drip ring to the tube. 

5. Attach the Diffuser

The final step is to attach a diffuser to the bottom end of the tube.  This scatters the light from the tube around the room.  Usually, you screw a ring into the ceiling, and then attach the diffuser to the ring.  You’re done, except for cleaning up all of your mess! 

In general, I’m happy with the results of our installation.  The solar tube provides enough light that we don’t need to use electricity for “normal business” in the bathroom during daylight hours.  Although the small tube is adequate for our needs, I’d use a larger tube for most applications.  Good luck!