Cordwood home building method

[2StateTrigger]

Good afternoon everyone, I have a question for the "higher powers" that be. 

I'm selling some logs in bulk and a potential customer of mine wants to be a portion of my logs on hand.  So here's what my customer is wanting to know.

She's building a cordwood home and wants to know how to calculate the number of cords of firewood (or calculated in # of boardfeet).  She's building a 15x20 home with 2 stories (ie 16' walls).  Does anyone know of an online calculator that might be able to compute the # of cords that she will need to buy in order to build her house.

Many thanks in advance.


Best Regards,

Jeff

[btulloh]

The firewood guys have a rule of thumb for figuring out how many cubic feet of wood is in a cord of stacked firewood. You might want to put the question in the firewood forum, or maybe they'll see it here.  There are threads about it if you search.

A cordwood wall is pretty much like a stack of firewood.

[Don P]

The firewood guys have a rule of thumb for figuring out how many cubic feet of wood is in a cord of stacked firewood. You might want to put the question in the firewood forum, or maybe they’ll see it here.  There are threads about it if you search.

A cordwood wall is pretty much like a stack of firewood.

Ah, then face cords would be easy to figger- 4x8', 32sf. 70 lineal feet of wall x 16' high (no gable logs in this)=1120 sf/32sf=35 face cords. Cordwood is often 2' thick, a cord is 4x4x8 so 35/2=17.5 cords. I think I'd round up to at least 20. Any extra is just heat the first winter.

[Old Greenhorn]

I think Don P. might have given you what you need, there is 128 cubic feet in a cord. Cord wood is usually split, there will be a lot more air in that 4X8 stack if these are all rounds. Less wood, more air in a 4x8 stack of rounds. I assume she is filling in between with some sort of mortar mix. Interesting project. I would guess that the first wall on this is going to give a good indication of how much material is needed. I'd love to see some follow up on this to hear how it goes. I have thought about this type of construction and would love to try it.

[LeeB]

I've always figured the type of wood would also be a big consideration. Seems to me you would want rot resistant for sure. Something like white oak, cedar, black locust, etc. What about the sap wood on any of these? would it need to be removed? How long would this type of construction last? Would it need to be painted or otherwise sealed on the exterior side?

[Jim_Rogers]

I designed a house to be built in WI with a cordwood exterior wall system. The frame was erected but I never got to see the wall system.

A friend toured a house in NY state that used that system.
Here are some pictures he sent me of the house:



 

 

 

 

Interesting that they used wine bottles to let in colored light.

Jim Rogers

[LeeB]

I've read a little bit about it since my last post and it seems that softwoods are the preferred material after debarking. Apparently they don't shrink and swell as much. Cedar being one of the better choices. Didn't say anything about removing the sap though.

[barbender]

There's a few ramshackle ones around here, they were big with hippies in the 70's. I can almost smell the reefer when I drive by one of those old places😂 Actually, it can make a beautiful structure. It makes a nice infill in a timerframe.

[hacknchop]

There are a few barns around here with cordwood walls Aspen is wood of choice around here because theres lots of it around, they usualy have sort of a post and beam frame with cordwood between the posts.

[Don P]

Locust is one hardwood exception that is preferred and it is rot resistant, either way I think I'd soak them in borate.

 Jim is that a reciprocal roof or are the interior beams simply crossing the corners at differing angles from the exterior walls, certainly a unique roof frame either way.

The steel saddle on the rafter connection is interesting. It is the same idea and saddle they use in large glulam roofs. The larger rafter is treated as a uniformly loaded beam overhanging support with a point load at the end, the smaller rafter is that point load. This is something to think about when thinking about the scarf moment diagram everyone posts, which, if you look it up, is actually the moment diagram for a continuous, unspliced, beam.

[barbender]

I think that round one is featured in Rob Roy's book about cordwood construction, I can't remember if it was his home or one he built. He seemed to be "the guy" when it came to modern day cordwood construction.

[btulloh]

128 cu ft in a cord, but a lot of air, so it's less than 128 cu ft of wood.

I like Don P's solution though. Get plenty, heat with the leftovers.

This type of wall looks like a lot of labor. I'd like to see some cost/benefit comparison to other forms.

[barbender]

The cost/benefit lies in the fact that you can do it with minimal building skills. If you can stack firewood fairly straight, you're golden. If you're one of the guys with a horrible looking firewood pile, this may not be the building method for you😁

[Don P]

Well, and materials are practically free vs framing, siding, insulation and interior finish. hmm, I wonder if the labor is really that high when you look at that task list for a frame wall.

[btulloh]

Good point. If the cord wood is your siding, insulation, moisture barrier, drywall, paint, ...

Just not my favorite look, but to each his own.

[Don P]

It isn't real easy on my eye either but not offensive, I'd rather look at a rock if I were doing it. There is an insulation cost in there actually, it is usually an outer and an inner strip of mortar with fiberglass, sawdust, vermiculite or perlite in the middle over and around the wood in the center of the wall, an inner and outer shell connected by the wood would be one way of looking at it, otherwise it would be miserable to heat.

[2StateTrigger]

Thanks to all who have replied.....

But the question still remains.....I already know that a cord of firewood is measured 4x4x8 = 128 cubic feet.  I'm still needing to know how much firewood it's going to take in order to build a 15'x16' wall.....Anyone have any leads or links? 

[btulloh]

If your sticks are 16" long it will take about 2 cords

[Hilltop366]

Think of it this way, in one cord there is three 16"x4'x8' stacks for a total area of 32 sq ft per stack times 3 = 96 square feet per chord. 

Then all you have to do is add up your wall length and multiply by the height, subtract your window and door openings and divide by 96 to get your required wood estimate.

I have always liked the look of a stack-wall or cordwood building.

[Don P]

I'm sure everything has been built at some point but I think generally they shoot for a 2' thick wall.

[btulloh]

Ahhh. Details are important and in short supply.

[RPF2509]

Years ago I came across a cordwood home using old growth redwood blocks 24" long.  The owner/ builder said he built it in about a week using chunks he had cut from roadsides around the property.  Cement was the  binder and he used old bottles in the wall for decoration just like  JR's post.  Interestingly it was circular as well (not so large as JRs pictures- maybe stronger,  more stable, easier to stack?), two stories and he had made the uppermost level to look like a medieval castle turret.  A center circular staircase radiused off a tree trunk and more trunks supported the 2nd floor.  He said all he paid for was gas for the chainsaw and the cement (less than $100) and the hardest part was mixing all the cement by hand.  During the summer he said a few gaps open up between the wood and cement but the first rains of winter swell all the gaps shut.  It insulates well so only a small wood stove is needed to keep it warm.  Checked google earth and its still there.