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Alright then. Perhaps I'll mount the panels on a teeter-totter affair in the yard, for seasonal adj., or change my house plan.
I didn't get it quite right last time, and I certainly would like to avoid major blunders.
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A-frames were designed for shedding heavy snow loads. Since they are all roof, and roofing is the most expensive part of building a house in the tropics, A-frames make absolutely no sense whatsoever here in Hawai'i. None.
Seriously.
There are very good reasons why traditional Hawaiian houses had fairly low gable peaked roofs. Among them is that a roof slope between 2:12 and 3:12 is best for efficient rainwater catchment.
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Interesting thing about being in the tropics, the north side of your house will actually see sun during the longest days of the year.
Hilo is somewhere around 19 degrees (too lazy to confirm at moment), and the sun varies +/-23.5 degrees throughout the year. In FF you'll probably still grow moss on the north side. In FF with any kind of shade trees, you'll probably grow moss on the south side too ;-)
On the south face, the steeper pitches will work better in the "winter", and not so well in the summer. Again, going with 19N, a pitch of 42.5 degrees would get optimal sun exposure on the shortest day of the year, and something like 68% insolation on the longest day of the year (cosine of a 47 degree angle...)
If you go up to a pitch of 24 in 12 - 63.5 degrees, then you're looking at incident sun angles between 21 and 68 degrees, or 93 down to 37 percent insolation - not ideal, but not totally dysfunctional.
.....
Thanks for the Heart update... I traded e-mails with him about joining his engineer's commune on Bahia Ballenas Costa Rica, it probably would have been a better move for the family than the one we made to Houston - if our newborn didn't get eaten by a Jaguar.
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I have to chime in.
A-frame is a poor idea here for many reasons. 4/12 pitch works well. Conventional stick frame. single story. Post and pier. Windows oriented to catch E/NE trade winds and a covered lanai 12x20. For starters.
Dan
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Daniel,
I'd say that an A-frame can be a fine choice if:
- you don't mind your rainwater runoff blasting down off the bottom edge
- you don't mind having no windows (light or ventilation) on 2 sides, or the complexity of roof penetrations to get them
- you don't mind paying for all that roofing material (just run the total cost for a similar home with conventional roof and compare, actually the difference is probably pretty small if you're using something like metal encapsulated foam panels...)
- you don't mind putting your A-frame up on stilts, or you like waking up with millipedes curled up on you, centipedes under the bed, easy access for people to climb in your windows, etc. etc. etc.
The weirdest vacation home I was ever in was a 3 story A-frame, about 300 square feet on the bottom floor, just wide enough for a queen bed on the top. The people did it to get up high enough that their bedroom had a water view, if you love stairs you might have been able to stand that house, I think they had to haul the bed up the outside and through the window.
Having said all that, I've been kicking around a house design that's a little like an A-frame in the middle - 7/12 slope through the middle section, 3/12 slope on the outside - The 7/12 slope makes a decent loft space, lots of light and air coming in the east/west sides, and is still very close to optimal solar performance. The 3/12 slope still has "normal" walls on the north/south sides and slows down the rain runoff.
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Don't forget the covered lanai. You'll be sad if you do.
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Wow, thank you, OpenD, DanielP, & Trevor.
I woke up this morning and realized that the roofing was going to cost twice!
I'm originally from the NW, the Cascades is where I have the most construction experience.
I definitely understand the value of having covered area. I'm going post & pier, but
how high, um, that's a challenge, as 4 feet is good, six feet more storage, but more stairs again.
I'd like a wrap around covered deck, but that seems extravagant, and a security issue.
I assume everyone has seen the school on Old Volcano Road? The one with the translucent roof?
Eh?
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Forget what I said about the school with the barrel roof.
I've read that 4 foot eaves are desirable. In my previous life, and county,
the regulations stipulated short eaves, because of wind. If you wanted a 48"
unsupported eve, the building department mandated 2x10 rafter construction.
What are the thoughts here? Rafter/hurricane ties sufficient? 2x8?
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We have 4' unsupported eaves around our house. The roofing is 2.5" foam sandwiched between metal directly attached to longitudinal steel beams and the house perimeter. The roofing is strong enough that you can stand on the end of the overhang. It's fairly easy to install even for us amateurs. No trusses! No termites! We purchased it through Rob Tucker whom I'm sure can give more details.
There's been some discussion on the new building code requirements for insulation. We can definitely say that having the built-in insulation in the roof has been great. Before the windows and doors were installed the building crew would gather under the new roof for relief from the hot May and June sun at the time. Very noticeably cooler. Now, even with windows always open, the interior stays several degrees warmer at night and cooler during the day. The foundation is a slab and the walls are 4" foam SIPs which also helps temperature control.
White Cloud Nursery
www.whitecloudnursery.com
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Structural insulated panel? I'm nervous about any kind of foam, except perhaps white beadboard, and maybe styrene foundation foam. I've see too much heartache from insect damage.
Thanks for tips about the value of insulation.
Is pink fiberglass have any downsides on the island, provided that it is properly vented?
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