Sunroom Questions: New Additions

a sun room with tan stuffed furniture

Q. We have a screened porch, facing east, on the back of the house. I want to replace the screens with a glass wall and use the space for a home office. There is an existing roof and insulation between the joists. Two eight foot sliders lead from the house to the porch. The porch has a cement floor. There is no heat or air to the porch, although the ducting is right there. The glass wall will be 24' long, and the glass sections will be 50" with about a 32" knee wall. The glass sections will open and have screens. There will be a six-foot slider to the back yard. Here's my problem: The Four Seasons contractor insists I need "wonder glass" from Four Seasons. C-Thru says that, because of the eastward face, only double pane is needed. C-Thru has a "smart glass" option that is about the same thing as "wonder glass." They say I don't need it. I want to make sure I have a room I can use all day, every day. There's a significant cost difference due to the differing glass requirements.

A. "Wonder Glass" and "Smart Glass" are both a low-E glass. It is worth putting the money into it. This conversion, regardless of which glass you use, is a sizable investment. Paying the extra to upgrade the glass will pretty much assure you that you will be able to use the room "all day, everyday." If you opt not to upgrade the glass, you may find that the room is unusable on both very hot days and on very cold days. A low-E glass will reduce the amount of energy needed to heat and cool the room. That not only will result in lower utility costs to you, but also will make life easier on your HVAC unit.

Q. We are turning our screened porch into a sunroom. We fear water will be able to flow into the sunroom. We want to raise the floor, which is a slab of concrete with a subfloor like a deck, add plywood and 'Durarock' and finish with tile. Can this be done? Will there be any problems? Do you recommend insulating this subfloor? Can we put this subfloor directly over the slab, and can the wood touch the concrete - will there be any moisture problems? We are thinking of doing everything first, putting in the windows, doors and everything else, and the last thing would be to raise the floor.

A. Leave the slab just as it is and simply put a French drain around it so that the water couldn't get inside the room. Build a trench 6" to 8" wide, a foot deep, with perforated ADS in it, and filled with 3/4" rock. Connect that ADS to solid ADS for a discharge line and run it away from the room and house to a gutter or storm drain.

Q. I am completing a sunroom addition, fully enclosed and heated with lots of windows. I installed tongue and groove cedar for the interior walls for its durability, but I'm wondering if I should be concerned about UV damage. The windows are good quality low-E glass. What's the best way to keep cedar looking good in this situation?

A. Low-E glass will block a high percentage of the UV rays, but not all. You might want to consider sealing the cedar with a clear, UV blocking, exterior grade, and polyurethane sealer. Find it in the paint section of any big box store or any paint store.

Q. I would like to build a four-season sunroom onto my existing deck. I have scoured the Internet looking for a kit, plans, do-it-yourself, etc. Most things I've found point to a book or video. Are there any suggestions on a book, video, or web site that would address my specific situation?

A. Don't take on this project as a do-it-yourself project, unless, of course, you live in an area where it never rains. If you live in an area where it rains, you will be fighting leaks forever. If you build what you are describing, and want it to be treated like a patio room by the building department, you will have to meet the requirements of a patio room. It needs to be 65 percent open (to a height of 80" off of the floor) on the longest wall and one adjacent wall. The only way to meet this requirement is to have all panes of glass in the window frame removable. You will have to design and build all the windows at least in the two walls in question that way. If you don't meet this requirement, the building department will treat your "four season add-on" like any addition to a house, and you will have to meet all of the codes that are involved. The folks at the building department will work with you in the planning and drawing stages of the project, but it will probably take you many discussions with them to get it designed to satisfy them.

Q. We thought we were going to get a manufactured sunroom addition, however, we've decided to build it ourselves and are seeking information on the best way to construct the roof windows to insure no leaks. Additionally, what is the largest recommended span between joists? Our joists will be four feet long. The sunroom is 4'x 8'.

A. There are things that would have to be considered. How much of a snow load do you have to meet where you are? Will the room be subjected to things falling out of the sky, like pinecones? This will determine the best material to use for the roof panels, but probably either tempered glass or Lexan will work. How much clear ceiling will you have, and how much will be solid panel? This roof will generate a lot of heat, and the more glass you have, the more heat it will generate. What sort of a climate are you in?

As far as making the joists and sealing them so they won't leak, try a "T" shaped joist, installed upside down, so the roof panels rest on it. Use neoprene or rubber weather stripping between the joist and the glass. On top, cover the joist and about 3/4" of each edge of the glass with a cap, again, with the same weather-stripping between the glass and the cap. Leave room on the edges of the glass for expansion. Personally, I wouldn't span over about 2' between the joists, but the snow load will determine this.

The thing to remember when designing a glass enclosure is that it will leak either by condensation or penetration. To avoid having to deal with constant nagging problems provide an exit (known as seepage) for these leaks. I recommend using a special purpose aluminum extrusion attached to a wood frame. This is called a skin system in the trade. Find a supplier in the back of home project magazines. These extrusions have a built in gutter to channel water to the exterior. The second most important issue is the layout. Size your sunroom to accept standard sizes of safety glass, i.e., 34"x76" or 28"x66", etc. Don't forget flashing where the structure joins the house.

Q. I really want a sunroom on the deck off the master bedroom. The bids are coming back way too high. In an Internet search, I got many different options. I want some glass on one wall and the roof can be the polycarbonate, but not solid since I do not want the room to be darkened. Should I look into the kit option?

A. If you put on a polycarbonate roof, several issues need to be addressed before you do that. Snow load is one. Whatever you put up will have to meet the snow load requirements for where you live. Solar heat gain is the other. Forget about the room; a totally polycarbonate roof with glass walls will cook your house, and you will pay a fortune trying to keep it cool. You should sub out a portion of the work, like possibly the slab, probably the electrical, and the finish of the interior walls. But you can do the actual construction of the room yourself.

Q. I have received approval to build 14 by 24 foot sunroom. Three sides and the roof will be argon filled, glazed thermal glass, the best I could find. You can enter from a door to the rest of my home, but the room will not be and cannot be connected to the HVAC of my home. Limited electricity at 110 volts is available. What do you suggest for heating and cooling?

A. Passive works. Keep the windows closed. Lots of glass, and lots of masonry will get warm and release heat as it cools. Talk to an electrician and find out just how much amperage you safely have. Get his opinion about possible heating systems. Check with your local building department. I'm sure that they will tell you that this room is "non-conditioned space." That means whatever you heat it with has to be portable, something that you can plug into an outlet. If that is what they tell you, you cannot put a permanently mounted heating or cooling system in the room.

Q. I am adding solar screens to our sunroom, which has four patio doors facing west, and two facing south and the heat in the summer is a problem. I can't decide if it would be better to have a solar screen made the exact size of the patio door and leave it in place all summer or if I would be better off getting a roller solar screen made so I can lift it up out of the way in the evening and drop it down during the heat of the day? Would leaving the solar screen up all winter afford me any added R-value to my windows?

A. If these patio doors are dual pane, you could have the glass IG units replaced with IG units with Low-E or Low-E squared IG units. That would reduce the solar heat gain in the summer and decrease the U-factor (raise the "R" value) for you in the winter.

Solar screens work well on windows, where you can screen both the movable and stationary pane. On sliders, you need the movable side to open so you can walk through it and the stationary half to remain stationary. That could only be accomplished if you were to mount the stationary side out a bit, so the movable screen would slide inside it, much like forming a pocket door.

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