Saturday, May 14, 2011

Advice to a prospective home builder

I get quite a lot of letters -- five to ten a year -- asking for advice on building with local materials. I like to post them to the blog so I can save them for re-use and reconsideration later.

For those readers who don't know, Aimee and I once built a house using straw bales. At the time it was one of the first bale houses in Maine, and used a lot of recycled and reused materials to boot. It cost less than $20,000 and, after a recent rebuild, still stands and is the current home of another Unity College faculty member.

But these days I advise circumspection and forethought before using a lot of straw bale in a home, and point out that straw is not actually local, free, or even that native to this part of Maine.

My favorite local materials, after years of trail and error, are actually field stone and green hemlock lumber.

The former is widely available in very large quantities, quite handsome when properly placed, and free or nearly free.

To most Mainers, field stone is a nuisance to be gotten rid of. You can get it by the truckload for nothing or next to nothing.

While hemlock lumber is stout, resists rot, and widely available from local sources, such as Gerald Fowler's mill in Thorndike, for around 45¢/board foot, which is less than a box-store two-by-four.

I sometimes daydream that if I had nothing else to do at all, no classes to teach, no wind research to do, I would like to take about five years to build a stone house.

One stone at a time, no rush, no worries, out in the wind and sun and bugs.

The Zen of Building.

That might be my retirement project.

This latest series of letters is to a recently-hired, new Unity College faculty colleague who will arrive with his family this fall from Out West, and wants to home-build. He wanted to talk about straw, but my gut instinct, after learning the hard way, was to want to think and write about house-sites and foundations, about sun and stone and, yes, even the evil climate-killer, concrete.

It's been reorganized so the first letter is posted first:



The first thing I would say is, this place is cold. Way colder than NW Montana, for instance. I don’t know of anyone who has survived a Maine winter in a yurt. I managed the first half of a Maine winter in an as-yet uninsulated house once, and it was very hard on me and my animals. (This was the bale house before I managed to finish it.)

Our straw bale house worked well enough until I married, and then we had to move. It was too far from campus for both of us, and way too off-grid for my wife. It still stands and serves after 8 years and you can see it if you like. XXXXX (another UC professor) lives there.

But I wouldn’t build another one like it. I’d use more conventional materials. If I had to do it over, I’d use post-and-beam pine and/or rough-cut hemlock studs and sheathing, cedar shingles, ordinary drywall, cellulose insulation, and normal wiring and plumbing. I might use locally made SIPs if I decided to go post-and-beam.

I’d put in a full septic, and make a super-insulated passive solar design.

It would be cheaper than straw bale, last longer in this climate, use more local material, insure more easily, be more fireproof, and have better resale value.

You see, the maine (pun intended) ecological difficulty is that we don’t grow wheat, rye or barley for straw within 100 miles of here, but we do grow and cut local pine and hemlock and cedar lumber, and do so on a small and sustainable scale, and cheaply. Hemlock rough cut lumber retails from local mills for 45 c/board foot or less. That’s cheaper than regular studs from Home Depot.

Straw has to be trucked further and is expensive.

You can even cut your own lumber off your own land and mill it, or have it milled. 20 c per board foot is the growing rate.

Before buying land for any kind of house, the first question I’d ask myself would be how far I was willing to live from work. Unity is more expensive than other places. Jackson here, fifteen miles away, is cheap. We got our three acres with almost-too-far gone farmhouse for $60K. We had to rebuild it and add a new septic, but we paid around $85K total in the end.

Then I’d investigate the planning regulations in the towns I was willing to consider building in. You can often download those from the Town Office web sites.

Then I’d go looking for land. Be sure to get sloping land that has vegetation that grows only on well drained sites. Anyplace flat around here gets wet in spring.

The best house sites have all been built on before because the old timers were more plentiful in Maine than current rural residents. They knew to build on south facing slopes wherever there was soil. Pick a gently sloping southerly-facing site away from noisy roads and neighbors with some pockets of deep fertile soil, first and foremost.

Everything else is secondary.

You may have to buy an existing fixer-upper, and rebuild it or knock it down, to get a really good site, just because the best sites we picked two hundred years ago.

But if you get the right site, sunshine and peace and quiet and good growing soil will be there when you want them.

Aimee’s web page: scroll down to see the “new house”




High efficiency in walls and roof are important, but still secondary, after choosing a good site to build on.

We're at 44 degrees latitude here. The sun only climbs 23 degrees above the horizon in midwinter. When we built the bale house, we learned this lesson the hard way. Even with the best insulation, if you build in a site with poor aspect, you may not get the sun into your rooms for weeks or months. And with so little daylight in winter, that sunshine is essential for health, especially psychological health.

Since you and I began corresponding yesterday I've been noticing other people's house sites more, and I'm still struck by the difference between sites where the really old houses (150-200 years) and the relatively new ones are. In the country (not the small villages and towns where access to streets was more important), the older houses are much more often found on knolls and terraces. Houses built in the last hundred years are less likely to be so well sited. Part of this would have been simply that the best sites were used up, but once coal became widely available, it must have allowed builders to pay less attention to aspect. Oil heat, which is still what 71% of Mainers use, continued to foster the disconnect between Mainers and sunshine. But the old timers knew better, because they had to split their own wood, sometimes as much as twenty cords a year, so they wanted that sunshine.

It's sunny here in late January, February, and the first week or two of March. Cold, Canadian sunshine, but free solar energy all the same.

Drainage would have been a good reason to choose the knolls and terraces too.

The next thing I learned from the old house is, you either build a cellar/basement, or you build on an Alaska slab (insulated floating slab-footing combo), but you don't do anything in between.

Which of the two you do may depend on your site.

All cellars/basements around here at at risk of filling with water. Most actually do fill with water at least twice a year. Much of Maine is actually below the water table once or twice a year.

We live in a giant seasonal wetland -- the main reason straw bale becomes complicated.

But old-timey cellars are great for root crops and OK for a place to put heating and hot water systems. And, if you build into a slope or terrace, you can provide a level entrance to the basement, and make sure that surplus water can get out this way too. This gives you security against the day when the water level is rising and the power gets cut off at the same time.

Maine's power supply is fairly tenuous, because of nor'easters, ice storms, snow storms, wind storms, thunderstorms, and hurricane remnants. These days we even get occasional tornadoes. We usually get a power cut every couple months and being without power for three days is not unusual. Rural Mainers like to have back-up generators to run sump pumps and home-grown food freezers when the power goes out.

In the Great ice Storm of '98, before my time here, but a historical point by which many Mainers set their clocks, people were without power for up to two weeks.

If you're planning to build off-grid this cellar/power supply/groundwater inter-system nexus thingy may seem like it doesn't apply, but it actually does. Most off-gridders can't afford to own enough solar panels, or a big enough wind turbine, and the necessary batteries, to be sure of having power to run a sump pump (that may draw 500W or more/hour) when the time comes. But neither can they add enough panels to run a big fridge or freezer or both.

One option is to build on a slab and add an above-ground level root cellar later.

But by far the most convenient option, and the one the old timers choose a lot, is to build into a south facing, well-drained terrace and leave a level exit to your cellar. And now I know why they did so. My 110 year old cellar, which stores potatoes all winter perfectly, would also drain itself if the sump pump were out. Duh. And a cellar can be built with stone, which is good for the climate. And you don't need to go out to the cold to get your spuds from your remote cellar when you need them. One less pathway to shovel, one less thing to worry about when the snow flies.

(One important seasonal Maine routine is to get your dooryards and barnyards ready for winter, by which I mean you move things around to minimize plowing, provide places to put snow, and so that you are sure that anything that will be under the snow can be safely ignored until April.)

If you decide not to have a cellar, which I would recommend if for some reason you are unable to get a good site with slope and southerly aspect, then build a serious Alaska style insulated slab.

The reason for this recommendation is again based on Bale House experience, and observation of the energy efficiency results from other houses.

Lots of home builders decide not to deal with concrete or to minimize it, and we followed this thinking when we built the Bale House. I thought I could build on piers and avoid the expense and climate emissions. I also, if I fess up to myself, wanted to race ahead and get to the straw bale part. I was anxious to be green and use "natural" materials. Piers are quick and easy.

But any big air space under the house is where all the damp and cold air comes from.

If it's a well-designed cellar, you can control this in part by sealing and by putting a heating system down there to make waste heat and dry out the air a bit. This is what most people do with typical ranch house basements around here, and apart from a mild diesel smell from the oil heat system, it works well-enough, particularly by helping solve the dampness problem. The waste heat dries the underplace out a bit. Seal it up properly and you can control air infiltration. In our energy efficiency work we're learning to deal with sealing basements and improving air quality at the same time. Be sure to add a source of combustion air for the heater. A lot of folks put a wood furnace down there, which really dries the place out well, but then you don't have a root cellar any more because the temperature has increased too much.

Cellars and basements are not a perfect solution and the air quality is still bad, but it's a compromise. You can at least go down there and fix things.

But if it's just a crawl space, life sucks. You get all the problems of damp and bad air, but you can't fix them easily, and you get none of the benefits of a cellar or basement. Nowhere to keep your spuds, nowhere to put heating and other systems, and lots of damp and bad air and mold. All that -20 degree air blowing around under the house in winter.

I haven't mentioned carpenter ants yet. They're a whole other consideration.

So a slab is way better than piers. If you can't have a basement or don't want one, don't settle for a crawl space. Just forget you ever thought about putting any kind of underplace under the house. You'll be much happier if you don't. Build a slab.

But it gets really cold up here, and basic slabs that are not properly insulated get cold. Your house will need to be heated more just to warm up the cold slab a bit just because people's feet will be cold and if your feet are cold, you feel cold. You can partly solve this problem by insulated the slab and running hot water heat pipes through the slab, but by far the best thing to do is to make a floating, fully isolated, fully insulated slab with the heat pipes. If you add a footing, you can get the house a bit further away from the wet ground.

We now do insulated floating slab and footing combos for all our campus buildings, after long and painful experience with flooded basements and cold, uninsulated slabs. There are emissions, but the buildings are much nicer to live in and use.

Like I said, site comes first, then plan your house from the ground up. You can put any kind of house on any kind of foundation. But decide on the foundation for the right reasons and match it to the site. An old fashioned stone cellar sealed up with some modern product on a south-facing hill or terrace with a level exit is a good choice. If you can afford or find granite, use that -- a local product. An Alaska slab is another good choice, but uses more concrete. This adds climate emissions but we make cement here, not thirty miles away, and we make aggregate here too, so the emissions are in the lime-making, not the trucking.

You can put a bale house or a post-and-beam house on a cellar or an insulated slab, but if you put any kind of house on piers with a crawl space, you're saving up misery for later.

You ask about clay, and we have lots of it here. I often think it's another overlooked local building material. It makes good rough adobe and good rough clay plaster. Sand is the key issue to mix with the clay. Although we have lots of glacial sand pits, native Maine sand is inconsistent and coarse, and so makes for a less smooth experience in adobe-making than fine western sand does. Little rocks in the sand spoil the finish and make it hard to spread. But it's a very cheap building material, almost free. Most gravel pit owners know where they also have a bit of clay, and people truck it to your site for a few dollars a yard. It's needed for earth ponds, is why there's already a supply. Be sure to ask to see it first, to make sure it's good, clean, consistent blue or yellow clay. Many plots of land will have a clay deposit of their own.

Any outside wall covering made of clay plaster or adobe in Maine that doesn't have serious protection from soil moisture or wind driven rain is a potential problem, and the answer is to build on a tall footing and add a large overhang. It helps to add a little cement, one or two percent, as a stabilizer.

(Another good reason to consider using some concrete in your house. to get a tall footing. But granite blocks or field stone cellar walls would do as well.)

I have an experimental patch of clay wall covering on the Bale House that has been open to the weather for eight years now and is still going strong.

You won't find it easy to insure a clay-walled house. though.

A different solution for a bale house wall is to add a very lightweight wooden sheathing, and use instead a different native Maine siding -- cedar clapboards or shingles. This is what we did with most of the Bale House.

Again, what is native may surprise you, when you think about it.

Sand, stone, clay, hemlock, pine, cedar, cement, and lime are all found or made within thirty miles of Unity, Maine, and have been used for generations, and the lore of how to use them well, and poorly, is available far and wide.

Straw is only available from further away, and essentially experimental and unproven in this ecosystem.

Hope this all helps.


No comments: