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A-Frame Pros & Cons - Suitable for Hawaii? - MarkP - 03-05-2011
A recent post stated that A-frames, being designed with a steep pitch to shed snow and being all roof, had absolutely no business in Hawaii. Another post followed closely that listed some conditions under which an A-frame might not be a total waste of time, including being built on stilts, but nevertheless made it clear that that poster also thought A-frames were a poor fit. This got me wondering, as it seems many of the pictures I recall of ancient hawaiian houses had extremely steep roof pitches and very low walls. By looking up "ancient Hawaiian house" I found a book titled "The Ancient Hawaiian House" that finally got around to talking about hawaiian houses after discussing all the houses in the rest of Oceania. Darned if the vast majority of them didn't look exactly like A-frames on stilts! In one picture the house appeared to be about 7 feet wide and 20 feet tall!
I think it is true that A-frames as we know them are associated with mountain or lakeside cabins from North America, where it snows, and it is definitely true that they shed snow, but it does not follow that because they are good where it snows, they must be bad in the tropics. I don't believe that the A-frame concept is driven by the need to shed snow, since more conventional cabin shapes have been routinely built in these same regions, as much as it is driven by the sheer simplicity and strength of a design based on triangles. Against this simplicity is balanced the poor use of space, but everything made or done by man is a compromise. My point is that based on my admittedly cursory research, the profile of an A-frame house would not have been out of place in the polynesia of 500 years ago.
What are the benefits of an A-frame design?
1. Simplicity. In ancient times joining logs was not as easy as it is today with Simpson brackets and stainless fasteners, so the fewer the joints the better and a triangle is inherently strong. This simplicity would not be nearly as important today but nevertheless it is a merit of the design.
2. Steepness of the roof. Ancient thatch was pretty neat but I doubt it was 100% effective and its effectiveness would depend largely on the steepness of the roof. Again, not nearly so important today but a good friend of mine, a carpenter for thirty years, stated that a benefit of a steep roof is that there is less corrosion of the roofing steel since the water drains and the roof dries quickly. In Puna we have to contend with lots of rain so in fact a steep roof does have some merit. Ya gotta admit it is the ultimate in having the roof extend far enough to completely shield the walls, at least on the sides.
3. Height of interior space. Among the faults often listed for A-frames is that they are difficult to heat. All the heat goes to the top. In my opinion this is because part of the mystique of the A-frame cabin by the lake is the enormous bank of windows from floor to peak on at least one end of the structure, coupled with the half loft design that is almost always chosen, creating a dramatic "great room" effect. Remember though, this is typically in snow country. This is exactly what you would want in the tropics, and what you should avoid in snow country. I bet that some of the negativity towards the A-frame stems from this and other foolish compromises made on behalf of style. Ironically this concession to style, so foolish in cold climates, has tarnished the image of A-frames for critical thinkers to the point that they are not taking the time to reevaluate and see that it is actually a benefit in warm climates.
4. Low maintenance supposedly because it is mostly roof.
5. It's a mystique thing. It pleases me.
What are the disadvantages?
1. Poor/weird use of floor space. Gotta admit this is true.
2. Tallness means lots of stairs. Yup.
3. Dark in the middle unless you build dormers. Guilty as charged. I would not put dormers in myself because then you give up simplicity. That was one of the main reasons for going with the A-frame right? All roof, no wall except on the end. No roof penetrations except up near the peak so there is less chance of leaking. Simple, clean, effective if you can live with it. This might limit the size of an A-frame so that you have one room on each end with windows and doors, and only non-habitable spaces like toilets and laundry rooms in the middle.
4. Roof is more expensive than wall. This may be true. I haven't crunched the numbers myself but I can believe it.
5. It's a mystique thing. Silly dreamers. Wouldn't want to be one of them.
So in short I can see putting a small A-frame up on stilts about 7' off the ground so you could park underneath and otherwise repel invaders. It would be about 20' wide which depending on the angles would also make it about 20' high. It would have the typical half loft. This being Hawaii all the heat migrating to the top would usually be a good thing, although there have been times I have frozen my butt off in Eden Roc. Well that was when I was trying to sleep. The loft would be for sleeping so it seems that would all work out. Have a deck at one end where the entrance would be, nothing at the other end. You enter into the main living area. The kitchen would be back and to one side, the bathroom back and to the other side, the loft over the kitchen and bath. A real stair, not a ladder, to the loft.
RE: A-Frame Pros & Cons - Suitable for Hawaii? - OpenD - 03-05-2011
quote:
Originally posted by MarkP
A recent post stated that A-frames, being designed with a steep pitch to shed snow and being all roof, had absolutely no business in Hawaii. Another post followed closely that listed some conditions under which an A-frame might not be a total waste of time, including being built on stilts, but nevertheless made it clear that that poster also thought A-frames were a poor fit.
Yes, that's assuming you want to build a modern house, using modern materials. Historical Hawaiian designs had high pitch roofs largely because of the roofing materials they used. Palm leaf and thatch roofs the world over are steeply pitched because they are not waterproof. Instead they use the steep angle to direct the water along the fronds or straw or whatever to a drip point outside the walls. That's why all those quaint English cottages with the thatched roofs and sheep grazing outside have high pitched roofs.
If you intend to do rainwater catchment, steepness is your enemy. CTAHR has established that optimal rain harvesting is done with roof angles betwen 2/12 and 3/12.
Paging through a few reference books I have, I see that the style was basically an invention of the 1950s, and that it was most used as a style for second homes because it was relatively cheap to frame up and could go on a small lot; the restricted upstairs space dictated loft style sleeping; and yes... it shed snow well. Since it looked vaguely Alpine it became popular in ski areas.
There's one near me here in Volcano, and frankly, it just looks goofy to me in this environment. I'm much more into choosing a basic design because of its functionality.
RE: A-Frame Pros & Cons - Suitable for Hawaii? - lquade - 03-06-2011
my father, an engineer, built our home and chose the A frame specifically for this environment. he liked the steep roof to rapidly shed and catch water. (we have only bought water once in over 30 years when housepainters left the hose on) he also wanted it because it was structurally safer and we went through the big quake in the early 80s with no damage and again the october quake a couple of years ago. i do admit, the older i get, the harder the stairs are, but the kids when little loved zooming up the circular stairs. i have never had anyone tell me it didnt "fit in" but then, we do keep the snow off the roof[
]
RE: A-Frame Pros & Cons - Suitable for Hawaii? - TrevorKane - 03-06-2011
I'd say, as with all architecture, it's a matter of personal taste.
One thing I don't like about steep roofs is doing roof maintenance kind of things, if you need to put your body up on the ridgeline for whatever reason, 27' is a long way to fall, especially if you're falling on blue rock. Walking on a 3/12 slope is a breeze compared to extension ladders.
RE: A-Frame Pros & Cons - Suitable for Hawaii? - MarkP - 03-06-2011
It must be obvious to those who have read my previous posts that I sometimes think outside the box to the point where I am reinventing the wheel. Often the engineer in me kicks on and I consider the problems a challenge rather than just letting the idea go. I did so with the whole shipping container house thing, although I have not rejected that idea entirely either.
I am now into the phase with A-frames where I am feeling out all the pros and cons. Lquade, I would love to hear more about the house your father built. How wide and tall? How many bedroom? Just what is the effect of such a steep roof on water catchment? I can see it being a problem during really heavy rains but during light drizzles the water would only be trickling down slowly anyway.
RE: A-Frame Pros & Cons - Suitable for Hawaii? - OpenD - 03-06-2011
quote:
Originally posted by TrevorKane
I'd say, as with all architecture, it's a matter of personal taste.
Amen to that, brah! And Hawai'i probably exemplifies that principle more than anywhere else I can think of. In my area there's a plain vanilla (i.e., boring) HPM-kit type 1BR house for sale for $169K, right next door to a stunning classic to-die-for plantation house worth $1.25 million. Different strokes, ya know?
Here's a handy link for anyone needing a quick refresher on what A-frames are all about: http://www.shelterpop.com/2009/11/10/a-frame-houses/
As the article mentions, A-frames typically have loft type sleeping space up in the peak of the roof. In cold climes that's an advantage, because heat rises, so the beds are in the warmest part of the house at night. To me, in the tropics that would be a huge disadvantage.
Also, for rainwater catchment it is desireable to have a standing seam metal or corrugated roof, not shingles or asphalt roofing, due to potential health issues. A-frames with their large roof area are typically roofed with shingles. And fuhgeddabout tiles.
Also, since the steep slope wastes a lot of rainwater and energy due to inefficiency (at that angle the water tends to splash out of standard gutters, and typically will need to be pumped up to a storage tank rather than following gravity down to a storage tank from a conventional roof) it wouldn't seem to be the best choice where annual rainfall is low, like Ka'u or Kona. But you'd probably be OK in Puna, yeah? [
]Also, since the windows are typically only on the end walls, siting the building correctly to take advantage of natural breezes for ventilation during hot and humid weather would be critical.
Reason and rationality aside, I really just think they look dumb outside of snow ski areas. [xx(]
But as TrevorKane pointed out, different strokes for different mokes. [8D]
RE: A-Frame Pros & Cons - Suitable for Hawaii? - OpenD - 03-06-2011
quote:
Originally posted by MarkP
I can see it being a problem during really heavy rains but during light drizzles the water would only be trickling down slowly anyway.
I think maybe Isaac Newton would argue with this reasoning. [:o)]
RE: A-Frame Pros & Cons - Suitable for Hawaii? - leilaniguy - 03-06-2011
My house is basically an "A" frame over a first floor, hip roof, sort of a cross between Polynesian and Japanese farmhouse style. The roof is 45 degrees M/L. The rain does overshoot the gutters during downpours. The roof is showing it's age so there are a few leaks and I'm getting too old and fat to shinny up there myself and fix it or clean the moss off. Something to consider if you plan on living there forever.(And the loft area is stifling hot in sunny weather and a real headbanger all the time.)
RE: A-Frame Pros & Cons - Suitable for Hawaii? - MarkP - 03-06-2011
I value all the input even if it seems I am arguing or disputing certain points.
I have slept in Eden Roc dozens of times. I have never been too hot. Usually I have been too cold. I think much of the Big Island is not really tropical due to elevation. Take volcano for instance. They get frost!
Point well taken about the rain gutters. I don't know what options there are for rain gutters. Are there extra large sizes? I would be putting this thing up on concrete posts anyway so gravity feed to the tank would not be a problem. As for roofing I see no reason why an A-frame would be any harder to put steel roofing on than any other roof.
RE: A-Frame Pros & Cons - Suitable for Hawaii? - TrevorKane - 03-06-2011
I've laid roofing on 3/12 slope, and 12/12 slope - the 3/12 was much easier. If your A Frame is 24/12 slope, it's closer to attaching siding than it is laying on roofing.
I don't know if bigger gutters would necessarily catch all the water, I see "splash out" as the problem in a heavy downpour - you'll still catch water, just not all of it - if you're in a rainy spot, some water should probably be enough. If you are catching enough water, "splash out" could actually help to keep the gutters cleaner.