Glass – How to Buy It
A homeowner can get a lot for his money or a little when he buys glass for windows, doors or partitions. But if he knows which glass will do what, and how to buy it, he won’t pay double or triple prices for plate glass when he could have used heavy sheet glass, nor will he waste money by ordering glass by the sheet when he could have used a case.
Window glass, also called sheet glass, is the most commonly used in the house. In fact before glass walls and picture windows were used it was usually the only kind. It comes in two thicknesses, single strength and double strength; and in two qualities, A and B.
Grades A and B differ only in the number of small defects and waves. However, the difference is not ordinarily noticeable, and many dealers don’t even stock A quality because they do not believe that it is worth a 25 % premium.
Whether to use single or double strength depends mainly on window size. A good rule to follow is to use double strength for anything over about two feet square. How large can double strength glass be? If winds don’t exceed 70 m.p.h., double strength glass may be used in sizes up to 38″x48″, or 34″x72″.
The next price jump to crystal sheet or plate glass is very sharp. If you want a window wall consider the possibilities of working it out using the indicated dimensions of double strength instead of plate glass. This can be most attractive and at about one-fourth the cost. Go right across the room with 30″x72″ double-strength glass placed vertically. The distance of approximately 30″ to the floor can be plain wall or used for built-in bookcases, cabinets or ventilating louvers.
Buying window glass by the case is one way to save money. Glass by the case doesn’t cost much more than half as much as by the sheet. It’s also easier to handle. At economical prices you can afford to use glass liberally in anything you build or remodel or enclose. And, buying by the case does not mean you’re stockpiling it for years to come. Usually a case of window glass is whatever number of sheets comes nearest to totaling 50 square feet. Cases of very large sheets contain 100 square feet.
Crystal sheet, which is heavy window glass of good quality, is the economical thing to buy when the opening is too big for double strength.
Plate glass, which is polished to optical perfection, may be 1/8″ thick or for a big view window, 1/4″ thick. If you have a long-distance view through your window, you will need plate glass. Otherwise you can use crystal sheet; for short distances you will never notice the slight waviness.
For plate and usually crystal sheet, in sizes too big for you to handle and too expensive for you to risk breaking, you must figure on paying a higher installed price, which includes an expensive labor cost.
Heat-absorbing plate glass, while no substitute for air conditioning, does screen out approximately 29% of the sun’s heat. It is used in west windows of seaside homes, as well as in car windows. It costs about 5/2 times as much as regular plate glass.
Obscure glass is used where you want light but no visibility. For example, a wall of it might be just the thing for a basement recreation room where part of the basement is used as a garage or workshop. For this you would need the thick kind, say 3/8″.Thinner figured glass serves for entrance panels, cupboard doors and shower enclosures.
Transparent mirror glass is often used for one-way vision in entrance doors. Ready-made it is extremely expensive, but a glass dealer who makes mirrors can usually prepare it for you at about half the price.
Insulating glass is the modern, superior replacement for ordinary windows plus storm sash. Like any insulation, it usually pays for itself over the years in fuel savings as well as comfort. It consists of two or three panes sealed in units, with air spaces between the panes. A typical double glazed unit has two sheets of 1/4″ plate glass with a 1/2″ air space between. Originally all insulating units were made of plate glass, but it is now made in window glass as well. Unless you need large windowpanes, you can save about one- third by using the window glass kind.
In the long list of building materials, glass blocks rank as one of the most versatile. They can be used for exterior as well as interior walls or for partition walls that do not go entirely to the ceiling.
Glass blocks provide light plus privacy. They come in many sizes and shapes and there are special blocks made to control the sun. Furthermore, glass blocks are easy to maintain and special units are available to provide ventilation through glass block walls.
Glass blocks can be installed within a wooden frame or in a bed of mortar. Once you understand how to set class blocks in mortar – a project you might want to undertake to replace an existing basement window with glass blocks – then you will be able to handle glass blocks within a frame inside the house. Literature on interior framing of glass blocks is readily available from glass block manufacturers.
How to Work with Glass Block
The proper mortar materials and mix are important whether for laying bricks or glass blocks.
The proper mortar materials are Portland cement, hydrated lime, sand, water, and waterproofing compound. The addition of an integral water-proofer of the water-repellent type is an added measure to insure watertight joints. Manufacturer’s specifications concerning the use of this material should be followed very closely. Where a waterproof masonry mortar is used, no additional water-proofer should be added to the mix. For better results, accelerators and antifreeze compounds should not be used.
The accurate measurement of materials is important. Generally a 1-1-4 mortar mix is satisfactory. However, reasonable variations from the mix are permitted and allowable limits are covered by manufacturer’s specifications.
The consistency of the mortar mix has a direct bearing on the strength and weather-proof ness of the joints. Since glass blocks have no suction like bricks, the mortar must be drier… it should not flow or have too much slump. Too wet a mix makes it extremely difficult to get proper alignment of block joints, and cleaning time is greatly increased. The mix should he not too dry, not too wet, but just right. Here is a good thing to remember: Do not re-temper mortar after the ¡niti.il set has taken place.