cuestaroble, "Could you please provide a reference where any greenhouse, in the universe, has used "PVC instead of PE" as a greenhouse covering?" Quoting from this source, Greenhouse Covering Systems, on pages 8 and 9: "Modern plastics have become the only alternative to traditional glass for covering the greenhouse. Plastic glazings include rigid plastic structured panels, such as fiberglass reinforced polyester (FRP), acrylic (PMMA, polymethylmethacrylate), polycarbonate (PC), and polyvinyl chloride (PVC) panels. Thin film coverings include low density polyethylene (LDPE), polyvinylchloride (PVC), and ethylene vinyl acetate copolymer (EVA). These materials have been used in single, double and even triple layers to cover the greenhouse." PVC film is included in this listing of greenhouse film products. These Greenhouse Plans list PVC film as a covering option that is difficult to keep clean. Plasticulture in the Global Community - View of the Past and Future has some interesting information on the use of PVC use as greenhouse covers. The advantages and disadvantages of PVC on greenhouses are discussed in this greenhouse article. It seems that PVC as a greenhouse cover is much more popular in Asia than it is here in the US. MM

Marcy, If I may, make a couple of suggestions. My personal recommendation for you would be to use a fiberglass window. Fiberglass is impervious to moisture, chemicals, salts, etc. for your pool environment. It does not conduct heat or cold (thermal performance) and is not affected by extreme heat & cold either. Vinyl expands and softens (melts) at high temps, and contracts rapidly as it cools. This will cause it to become brittle with age. Aluminum conducts heat & cold, wood requires Paint & maintenance. So I would recommend fiberglass inside and out for your design. Most underground storage tanks, chemical equipment, and boats are made from fiberglass because of its strength and because it performs so well. Vinyl is the most cost competitive product sold today, however, I personally would stay far away from vinyl if your intent is longevity of your windows. Aluminum windows are still popular in your part of the country, however, even thermally broken aluminum will sweat in that environment. Let me qualify "Fiberglass Window" by saying an INSULATED (cavities foam filled for sound reduction if sound reduction is important) fiberglass window frame. Also Be very careful of what some consider to be or call "fiberglass" and what truly is fiberglass. For instance, certain companies have products that use the word "Fiber" in their name, but it is merely a composite of wood, vinyl, and fiberglass strands for reinforcement. Thats NOT fiberglass. True fiberglass is thermally set during the manufacturing process, and once cured (in about 20 Minutes) its shape cannot be changed by re-heating or melting. In the interest of full disclosure, I work for a distributor of winodw products, and thus have gained a VAST education in the subject of Manufactured goods & thermal performance. Thus, I wont recommend a specific product, but I will tell you that spending a little more for a fiberglass frame in your area of the country will give you many more years longevity, & they can even be painted (even dark colors) without voiding the warranty. If you think about it, Fiberglass windows & Glass (key components are derived from silica sand) are both made of the same raw materials. Therefore, what small amount of expansion and contraction they do have from hot and cold temps is minimal, but they will move at the same basic rate. This prevents separation of frame & glass, and degradation of the product over time. Tri Pane windows are expensive, and will improve your thermal performance and your STC/OITC rating, but not enough to justify the expense unless you are in a severely cold climate. If noise & thermal control are your primary concerns, I suggest you ask any window seller to SHOW you their STC/OITC ratings, their thermal (NFRC) ratings, and a Corner cut sample of the product you are interested in. Much can be learned about quality and serviceability by these 3 things. I do however recommend you use at least a doubled layered (LowE2 - 1 Layered and 1 sputtered) coating on your windows. Double coat low-e reflects heat gain in the summer and retains heat in the winter. It provides some solar heat gain during the winter months as well. This is difficult to explain, but the mental picture is this: The secong coat is sputtered on and done so at an angle. The reason for this is because the angle of the sun relative to the earth is higher in the summer and lower in the sky in the winter. Therefore, in the summer it reflects the suns rays and the winter it allows more of those rays to pass. Since the area is enclosed, without some sun protection, you simply wont be able to cool the area when competing with the power of the sun. I suggest you use solar sun shades for summer time as suggested above, this way you can manually control summer vs winter heat gain, and even on an hour by hour basis. Besides, they will also provide you privacy for a night swim if desired. As for your plants, Low-e coatings still allow a generous portion of the suns spectrum through to nourish your plants. My house is covered in vegetation that performs very well behind these coatings. I hope my knowledge helps you better understand how these things work. Best of luck! JH

"1. Type of wood to use??? I'm going to paint them. Poplar??" Poplar accepts paint well but is a disaster on exterior exposures. Pine actually works better here. Cypress or redwood wood be a step up from pine with the preference probably going to cypress. "2. Jointing? The simpler the frame is the better for me, but i'm not sure what would work best for seasonal windows." Half laps will be more than adequate. Use Titebond III glue. Wood movement is not usually much of a problem since the cross sections are normally less than 3-4 inches. You can get various types of weather stripping to make up for variations in the old windows and surfaces. Resources Conservation Technology has many styles available. Some for edges, some that go in grooves, etc. There are multiple ways to make the frames up and cut the required rabbets for the glass. A relatively low tech method is to build the frames and then use a router to cut the rabbet. Some hand work will be required to square off the corners. Prime, install glass (push points are a simple way to hold the glass before putty), putty, allow to set a few weeks, then paint.

If you can remove mounting screws first. If the screws are stripped they can be easily sheered with a chisel or oscillating tool. If you can't remove them they will have to be forced out when collapsing the frame. Start on vertical sides in middle by inserting pry bar between frame and exterior casing. Put price of wood between pry bar and casing to prevent damage to casing and start to bend frame inwards. Once beyond limits of prybar pull it in further by hand to about half way. If strong enough you can do it all by hand or if to weak you'll have to use a clamp or say f it and just wreck the aluminum cladding.. Do the tops next and just keep working it by hand and prybar ad needed. If they are back caulked you'll want to cut this free first, I prefer cordless oscilatting tool for this. I'd first post pictures to if this method would work. If the blind stops cannot be covered properly all this will be for nothing .