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Retrofitting for Sustainable Architecture

Kelly Hart is your host here at greenhomebuilding.com, and has been involved with green building concepts for much of his life. Kelly spent many years as a professional remodeler, during which time he became acquainted with many of the pitfalls of conventional construction. He has also worked in various fields of communication media, including still photography, cinematography, animation (he has a patent for a process for making animated films), video production and now website development. One of the more recent video programs that he produced is A Sampler of Alternative Homes: Approaching Sustainable Architecture, which explores a whole range of building concepts that are earth friendly. Kelly is knowledgeable about both simple design concepts and more complex technological aspects of home building that enhance sustainable living. He has even designed and built a solar-electric car that he drives around his neighborhood. Kelly, and his wife Rosana, live in the earthbag/papercrete home that is profiled on the earthbag page. He is available, at a modest fee, for consulting about sustainable building design, either for remodeling existing structures to more fully embrace these concepts, or for new architectural designs.

Questions and Answers

Q: I will be purchasing a double wide manufacture home in Ash Fork Arizona and would like some input on how and what materials could be used for the outside. I found a web site last year of a professor in Tucson who used foam board and stuccoed his home.

A: I presume that the manufacturer offers a limited selection of exterior materials, with likely fiberglass insulation in the walls. To make such a house "greener", you might consider some of these possibilities:
1) Orient the house to catch some of the winter sun, but with shades to exclude the summer sun.
2) Incorporate as much thermal mass material (tile, brick, rock, etc.) as possible inside the house to help stabilize temperatures.
3) Possibly increase the insulation all around on the outside, with something like the stuccoed foam board that you mention. A more radical retrofit might involve wrapping the structure with strawbales or earthbags filled with volcanic rock, which are then plastered on the outside.

Q: What's the best strategy to retroactively remodel to be greener?

A: The first thing I would consider to retrofit a house to be greener would be to look at the possibility of introducing passive solar heating. This can often be done rather simply and pays back such huge dividends in comfort, savings in energy costs, and diminishing the pollution associated with conventional energy.

Q: I am the Executive Director of Theater for the New City in New York City. We have a footprint of approximately 17,000 square feet. Our roof is flat. We would like to perhaps have a Green Roof or Solar Panels. I don't know where to start in this mission. Can you help?

A: 17,000 square feet of open space in New York City is a significant resource, and I am pleased that you are considering green options for capitalizing on this space. Both of the options that you mention may be feasible, at least to some extent. Certainly solar panels for both hot water and for electricity generation are likely possible.

As for converting the roof to green space, i.e. earth-sheltered and planted, this possibility would really depend on whether the structure could support the considerable additional weight of all that soil, and whether the existing roof could be sufficiently water tight to allow this. It might be that some partial accommodation of this concept would be preferable, even done as independent planters arranged on the roof for trees and gardens.

It will take the expertise of local technicians to ascertain how and to what extent any of these options might be realistic. Perhaps a combination of several of them would work. I can image a lovely roof-top park that not only features lovely plantings and paths, but also demonstration solar panels for water and electricity. One place to look for expertise in these areas is http://directory.greenbuilder.com .

Q: We are in the process of remodeling a house in Boulder. We are wondering if a 2-story house is greener that a ranch style, with the same total square feet?

A: Yes, I would say that in general a two-story house will likely be greener than the same square footage spread out on one level, because of the savings in both foundation and roofing materials. Also, the heat accumulated on the first floor can be used to help warm the second story.

Q: Can I retrofit an existing older house which has asbestos siding? I'm thinking to put something right over it, like straw/stucco or earthbag/stucco, or maybe just stucco.Aasbestos is scary stuff, but I've heard it's better to leave it on and cover it than to cause more problems by trying to take it off (which I wish I could safely do). By U.S. standards, we're "poor", but we've got a chance to get a pretty nice house. . .with asbestos siding on it.

A: You're right that often the most environmentally friendly thing to do with asbestos products is to leave them be, since it is the dust that is most hazardous. What you might cover it over with could be any of things that you mention. Earthbags and/or straw could provide much more insulation for your house, if this is desirable, but they would require further foundation or roof work to be practical.  Otherwise, covering the siding with stucco or recycled wood might be preferable.

Q: We currently live on over 5 acres and our home is over 3,900 square ft.....unfortunately our home is not very green. We're wanting to downsize and live off the grid....downsizing won't be a problem but going green can be difficult in a typical residential neighborhood.... Any feedback is very appreciated.

A: Downsizing a home that large would mean closing up some of the rooms and just not trying to heat or cool them.  In some climates there might be issues of frost with plumbing to deal with. The ideal might be to retrofit at least some of the house to be passive solar, so that it tends to heat itself...and of course to make sure that the house is well insulated.

To live off-grid is a fine objective. In order to do so you will need to pare down the amount of electricity the house consumes (or the appliances that you use). This will take some careful analysis of everything that uses electricity, from light bulbs to water heaters. You will need to add up the watts or amps they use over time to come up with a figure of how much electricity you actually use and compare this to what you actually need, if you were to conserve. You can look at your current electric bill to know a baseline for what you are consuming now.

Completely off-grid photovoltaic systems are possible if you set up a bank of batteries to supply electricity when the sun isn't shining, but this can be an expensive (and maintenance intensive) proposition. A simpler and less expensive approach is to set up a "grid intertie" system where the electricity that you produce is fed back into the grid when you are not using all of it, and then the grid supplies your needs when you don't have enough. This is also called "net metering". If your system is sized right you won't have to pay for grid electricity. A hybrid system with a small backup battery for absolutely essential items in your house when the grid goes down is another possibility.

Q: What is the best solution to stabilize a 875 Sq ft one story camp that is on frost heaved surface piers (unlevel)? The camp is on a lake in the Adirondack mountains on a very high water table (possible spring). The area is wet and in the winters gets extremely cold.

A: My suggestion would be to place those piers on deep rubble trench foundations that go down below the frost level. This should eliminate the heaving problem.

This type of foundation system was used by Wright, and I think it is a superior method. I only have the question of the high water table. I do not believe we can dig the 4 feet necessary to get below the frost line without hitting water. If that is the case, is there a work-around?

Just put some large stones at the base where any water might collect; I doubt that the frost will heave those. As long as there is plenty of open space between the stones and any gravel for the water to occupy it should be fine.

I was wondering if a complete perimeter trench needed to be dug with a concrete grade beam reinforced with rebar, for the piers to go on, or if for piers, you could do this only "under" each pier and would have to tie in a drainage system connecting them.ie "rubble trench".

I don't think you need the continuous trench for this; just an area of perhaps two feet diameter beneath each pier. You might seat the pier blocks in some cement to keep them from shifting.

Q: I live in upstate NY, super hot in the summer, super wet in the spring, and insanely cold in the winter. I found a dilapidated house in the hills with a nice looking wind turbine for pretty cheap and figure that it might be my first step towards sustained housing. The existing house is on a concrete foundation (with some cracks and holes) and the first floor is brick around the outside. The second floor is worthless. Siding is shredded, and the roof has gaping holes in it. Much wildlife currently in the house. Regardless, can you recommend any natural renovation methods that might be practical for rebuilding the second floor and renovating the first floor?

A: It sounds like the foundation and the brick portion of the building might be salvageable. In a very cold climate you need good insulation all around, which bricks alone do not provide. In fact the bricks are perfect for thermal mass, and are best kept inside the building. You could thoroughly renovate the building by insulating the brick walls on the outside with strawbales or earthbags filled with volcanic stone, rice hulls or perlite. This would require an additional foundation, but this could simply be a rubble trench right next to the original one. For the second floor, you have many options, from continuing with strawbale or earthbags to using recycled lumber and infilling with light straw/clay.

Q: What is the best way to insulate and/or add thermal mass using papercrete to an existing structure? Wrapping the exterior means extending the roof, new headers for windows, foundation, etc. Wouldn't it be easier to add mass to the interior? Could I mortar blocks to the existing drywall? How thick should they be? I realize that I'd have to move some electrical and plumbing and lose some sq. footage. A retrofit seems more feasible than the hassle and expense of building permits and structural engineers.

A: Papercrete is basically an insulating material. Adding thermal mass to the interior may be easier and more effective in retrofitting your house, and this can be done by adding bricks, blocks, stone, tile, etc. in various places; surrounds for stoves or heaters is one good place to do this. Tiling the floor is another option.

Q: I want to add insulation to an old mobile home and I would like a natural and economical source to cover and insulate inside walls. I was going to try the papercrete technique, but I was wondering if there is possibly an easier and faster technique to apply a wall texture but also to work as insulation?

A: I doubt that papercrete would be a good solution for you to insulate the interior of a mobile home. Unless you could somehow make fairly thin panels that are cured outside first, the wet papercrete would make a mess inside. One natural insulating plaster that I know about is described at http://www.styronit.com/en/isolation.php, but this is made in Turkey and may not be widely available. It is hard to think of other natural insulation materials that would be thin enough to be practical inside a mobile home. Most natural plasters are not insulating. You would almost have to go with some commercial industrial material to practically do this, such as thin foam insulation panels or even insulating paint, such as that described at http://www.supertherm.net/

Q: I want to take all of the sheetrock down inside my house; the insulation that was in the walls has disintegrated and we want to put straw in it, then just paint plaster or gypsum. I was wondering if you can do this with an existing wall? On the outside is metal siding.

A: You could do what you describe, but I see several possible problems. First the fact that a few inches of straw will not really give you very good insulation. Strawbale houses are well insulated because the walls are nearly 20 inches thick and the straw is tightly packed in bales. The other problem is that when straw is loosely packed it can be a fire hazard. Then, if the outside of the wall is metal and it comes in contact with the straw, moisture that might condense on the inside of the metal when it is cold outside could eventually rot the straw.

I think you would be better off using some other form of insulation in those walls. Cellulose insulation can be blown into the cavities and provides good insulation. It is mostly recycled newspaper that has a fire retardant on it, so it is fairly "green."

Probably the very best thing to do as far as having really good insulation that will never rot is a spray foam that seals the wall completely from both air infiltration and water vapor. But this is generally fairly expensive and not all that green...although you might be able find a bio-based foam product such as that made with soy.

Q: I'm looking to re-roof my home and looking for alternative roofing materials, i.e. lightweight cement, or progressive ideas to help insulate and protect the house.

A: There are many choices for roofing these days, and the appropriate one for you depends on the specifics of your situation. Lightweight cement is normally only used as a roof deck where poured concrete would be too heavy; it is not really very insulating. Here is one idea that I did once to insulated a roof: http://earthbagbuilding.com/articles/ceilings.htm

Q: I live in South Africa. I have seen your concepts for green house building, and I am passionate about the concept. I’ve got an old house that needs major renovations. The house was built with conventional building materials. The house has a problem of dampness from foundation to window level, dampness causes cement plaster and paint to peel off from the wall. The house was built in 1973. The roof started to leak. I want your advice, when I am renovating the house I want to consider sustainable principles and green house building technology. Where do I start?

A: Moisture within the walls of a house is always a problem, and the root cause of that moisture must be addressed. In evaluating a renovation project you need to determine what is salvageable and what is not, which often entails taking off some of the wall coverings, etc. Any materials that are too far deteriorated or will contribute to an unhealthy living situation (such as embedded mold) need to be removed. What is left might be useful in your renovation, or it may not, but this needs to be determined. Green renovation means reusing existing materials if they can be reused. So you are looking at a process of carefully evaluating what your goals are and what you have to work with to achieve that goals. Any new materials that are employed should be both natural and local as much as possible.

Q: I am looking to turn an old cabin (essentially a shed) into a livable abode. The exterior walls are currently uninsulated and are cedar clapboard attached to studs. I'm looking to insulate the walls (haven't decided on which form yet) and then attach reed mats or lath to the studs and adhere earthen plaster to. I was wondering if I need to put a vapor-barrier between the clapboard and insulation or insulation and plaster? Any other recommendations?

A: It is generally better to allow some permeability through wall systems for both the health of the inhabitants and the walls themselves. As long as the wall repels moisture on the outside, and keeps air from blowing through you should be be fine.

 


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