First log home, lots of questions

[Nathan Miller]

My wife and i are planning to build a 20x24' cabin this winter with 12x20’ loft in the woods in KY where we live now in a renovated bus. I’m trying to make all the decisions i need to make now so i can start asking for quotes on everything. So I’m at the stage of trying to put together a final wish list and see how close I can get to all of it. I basically want to get prices on everything to sub it out and then decide if I will need to do any of it myself in order to get our main requirements accomplished. My goals are to be very energy efficient as we will probably only spend half out time there and not go over my relatively small budget. We don’t want to skim on the insulation, roof, windows, doors, Heat and cooling. We only have about 3 hours of full sun but we would like to have a lot of windows all around, especially on the south and a couple sky lights. We are probably going with a log cabin of 7 inch Eastern White pine logs from a local supplier who harvests from the national forest just 2 hours from here, metal roof and considering SIPS panels for the ceiling and possibly the floor. I have read they are the best possible insulation for the money, cut time on construction, are stronger, don’t cost more after the labor savings, and I’m looking for opinions of people who know if all this is true or not. The roof pitch is steep. The plan is that the ceiling SIPS would rest over large roof timbers and they have eastern white pine tong and groove on the inside so the inside ceiling is complete upon installation. I think the metal roof can go right on top. I have several questions that I need some advice on.
1. Will they SIPS last the rest of my like i hope the log walls do? (I could still have 55 years to go)
2. Should I consider a heat pump or even geo thermal for such a small place that is going to be highly insulated with SIPS, if we go with them?
3. How much heat do I need? Would radiant floor heat and a heat pump be warm enough in cold winters at 10 degrees F or might I also need something else? I read that heat pumps will only work down to 30 degrees F.
4. Will the heat pump just shut off at near 30 degrees F or will it at least keep my pipes from freezing.
5. Is there any known problems using a wood burning stove in a small log cabin, like will it dry out the logs too much or anything?
6. Are skylights ever a problem installed in sheet metal roofs?
7. Would you recommend that I pay someone to write professional plans. Currently, I just have my hand written plans on paper. They are not close to scale but they show the sizes of everything.
8. I notice the prices of metal roofs differ greatly. Any opinions as to what grade and how much I should plan to spend and for how long of a warranty?

Thanks for any help you can give me! I’m ready to start immediately as soon as I know how to pull this off.

[rwanders]

A plumbing & heating firm can help you calculate your btu needs for heat and size a system for you.

Fireplaces are inherently inefficient----think about chimney cleaning needs if you use very often----don't dismiss that---chimney fires are a real threat. Fireplaces are nice though.

Skylights are ok if installed properly.

If you have a very competent contractor---your plans would probably work---unless local laws or building officials require stamped plans. Banks often require more formal plans if you will be financing the construction.

Properly installed,metal roofs will last almost forever.

SIPS lifespan is as long as the cabin.

[Don_P]

The log walls will give you between R7-R10, I've built log sided homes with triple that insulation level, something to consider if energy efficiency is the goal.

If the logs are green or anywhere close to it running the heat hard early on will increase checking. For a milled package dry logs are well worth the money IMO. Once the core of the log is dry there is little chance of damage from running a woodstove or heating to your desire. Since wood shrinks as it dries if the outer shell is drying and shrinking at a much faster rate than the still wet and swollen core it checks more heavily. Checking of large timbers is inevitable, you simply don't want to make it worse than it has to be. Respect the woodstove manufacturer's clearances.

A standing seam metal roof will probably last longer than you, an exposed fastener, screw down roof probably will not.

A heat pump will operate on electric resistance heat if the temperature drops below its ability to extract heat from the air. A geothermal will not drop to that point but isn't cheap to install.

I prefer a roof of structural beams, decking, layers of foam, sleepers, ply, felt and roofing. "Wrap and strap". Labor is higher, materials are lower, there is structure under the foam. Line up 10 guys and you'll get as many opinions.

Skylights are another penetration of the roof so are always more susceptable to giving trouble than no skylight. You also just put a R2 hole in your hat. They are much better than they used to be though.

Best luck!

[gkdesigntech]

The log walls are attractive for a while, but I've seen some that looked absolutely terrible after only a couple years. Log walls are rated at R1.25 per inch, so on a 7" wall (if that's an actual vs. nominal dimension) they'd come in at R8.75. A comparable framed wall is over R15. The latest energy code requires R18 for most residential framed walls in the central midwest.

As far as the plans go, I'm biased due to 15 years as a plans examiner in a building department and 25 years as a designer. No offense to contractors that try to draw their own plans, but most don't have any engineering experience. You are obviously wanting this home to last a long time and the only way to ensure that is to start with a good solid set of plans with all aspects engineered for performance and durability. The problem with "canned" plans from websites or magazines is that rarely do they contain sufficient or accurate detail for permitting or building, and they almost always require some modification. I'd be happy to walk you through the design process if you'd like.

As far as skylights go, in a metal roof they don't leak often, but they will increase your heat loss and solar gain (depending on which direction they face) which will drive up your heating and cooling costs. They also can lead to fading of furniture, carpet, etc.

You can email me at design_tech@windstream.net if you'd like more detailed information or help with the design of your home

[Bob I]

Nathan
SIPS would be an excellent way to do the roof, but I'd suggest strapping over it prior to the metal roof. If you go this way I strongly recommend buying Joe Lstiburek's book on SIPS. You can do the floor with them also but they'll need to be supported in mid span - you can get exact span from the manufacturer. You can get heat pumps that provide heat to -20o, but I'd want to make sure there are knowlegeable technicians nearby to service it.
Bob

[homeloversue]

I unfortunately can't answer any of your questions, but it sounds like a really cool project :) Good for you!

[lowbidder]

As for the skylights, they will almost always at some point leak. Your roof will indeed last forever, why mess it up with a skylight. As you can tell, I've had a bad experience.