When you are looking for a tunnel house it is important to make sure it is well constructed and that the plastic film is held securely if you want it to last. We looked at a lot of tunnel houses before deciding on these ones and these are the reasons why:
Horticultural Glass is made by the rolled glass process and is the cheapest form or glass. A continuous stream of molten glass is forced between water-cooled rollers to get the correct thickness. Horticultural glass often has optical imperfections and sometimes depending on the source, is not as clear as window glass (sometimes a bit green).
The only reason manufacturers use steel for frames in domestic greenhouses is price. These greenhouses are often made from electroplated galvanised sheet steel that has been cut and folded or rolled to shape. The protection layer is very thin, and the cut edges of course are not galvanised, so though the frames will last quite a long time, eventually they will rust. The sheet steel is also quite thin, so where it has been cut there is often a very sharp edge.
The only disadvantage with aluminium is cost. It is a more expensive metal and dies have to be made in order to extrude the product to shape. The frames are much thicker and in most cases have rounded edges from the extrusion process. Aluminium has a thin protective oxide layer on the outside that forms immediately the moment the aluminium is exposed to air. Any damage is instantly sealed off with an oxide layer. Aluminium never rusts and provided compatible materials are used with it, there is virtually no corrosion.
Aluminium will last a lifetime, and with the rising cost of raw materials it is false economy to purchase a greenhouse with a steel frame that you will eventually have to replace. We have a 10 year limited warranty on the frame. It is quite conceivable that a steel-framed greenhouse will have started rusting before our guarantee has run out.
You might think this is a simple question… but there is more to a greenhouse than you think. There are three main reasons for using a greenhouse. Protection – greenhouses offer warmth and insulation protecting your precious plants from the harsh elements such as frost, snow, wind and hail. Wider crop variety – growing in a controlled environment such as a greenhouse means you can effectively cultivate a much wider variety of plants than you would normally be able to grow outside.
Extended growing season – because of the warmth and protection you can start growing produce much earlier and (depending on your circumstances) grow right through winter compared to outside thus extending your growing season into the cooler months. A greenhouse also looks great, adds value to your home and offers a warm place for you to potter about on a rainy day.
Equally important is how it is constructed. The aluminium hoops fit into predrilled holes in the wooden base. The base is held to the ground with wooden pegs that are hammered into solid ground. The pegs are then are nailed to the base. The cover is held by a rebate and wooden lock strip nailed to the base. (Please note: While our tunnel houses are very strong this does not mean you can put your tunnel house up in an exposed situation and expect it to survive gale force winds. They are designed as a domestic tunnel house. Common sense needs to be exercised and adequate shelter provided).
Every greenhouse comes with a 10-year guarantee on the aluminium frame against faulty workmanship, much more than you will receive from most other manufacturers. The polycarbonate is guaranteed in South Africa for 7 years against breakdown (going brittle) by U.V degradation. If U.V breakdown occurs, and is confirmed by the manufacture’s sample analysis, a pro rata replacement credit will be allowed. A credit will be issued, based on original invoiced value, for the unused period of the warranty. Warranty is to the original purchaser of the greenhouse. The polycarbonate must be installed with the UV coated side to the outside (facing the sun) otherwise the warranty is void.