An H is the profile that is used to connect two polycarbonate sheets side to side. They are not meant to be used to connect sheets lengthwise. It is recommended that you purchase a polycarbonate sheet the proper length that is needed for your project.
There are two different types of H on the market. There is a one part H and a two part H. The 2 part H is sometimes referred to as a snap H or as a base and cap. They basically perform the same function – connecting two sheets of polycarbonate side to side. There are several basic differences, Polycarbonate sheet but the most notable one is how they are installed.
One part H’s are available in clear polycarbonate. Some manufacturers will offer them in bronze and ice also to match their sheets. The first consideration is the “dead air” space that will be between your two sheets. This is in the center of the H and varies by manufacturer. When building your frame you should allow for this space to assure proper placement of your sheets without having to cut them down. Once your frame is built you are ready to install the sheets. Attach your two sheets of polycarbonate loosely to your frame allowing for the dead air space of the H plus 1/8″ on each side of the H for contraction and expansion. Start at the bottom of the sheets and slide your H from the bottom of the sheets to the top of the sheets. Some people will have problems with this step. The H’s are tight and meant to be that way. You may need to use a very mild, very dilute soap mixture to lubricate the sheets so the H will slide. Also, if more help is needed, you may want to take a board to protect the end of the H and use a hammer to move it into place. Using one part H’s on sheets that are more than 12′ in length is going to be much more difficult than using the 2 part H.
Two part H’s, or base and caps are available in clear polycarbonate or aluminum. Some manufacturers will offer them in bronze and ice to match their sheets. The polycarbonate and aluminum will basically install in the same general manner. There is also a “dead air” space in these profiles. The base is screwed to your frame. You then lay your polycarbonate sheets on either side of the H allowing the 1/8″ space on each side for contraction an expansion. The polycarbonate cap will usually “snap” on. You can do this using the palm of your hand or a rubber mallet. The aluminum cap will usually screw into the aluminum base.
The two part H’s are typically more expensive to use than the one part H. But, they will save a considerable amount of time during installation, especially on longer sheets.
Tammy Wylie has been selling and installing greenhouses since 1993. She currently owns two greenhouses personally. A smaller 8 x 12 is used to overwinter plants. Her 18 x 24 greenhouse is used to start vegetables, herbs and annual flowers. She also tests new products in this greenhouse and evaluates them for efficiency and user friendliness. She is the owner of http://advancegreenhouses.com
For more information on this product, visit this page.