Acacia Dealbata (Silver watle) for roundwood timberframing - [Roundwood tiny house over ruin]

Hello all, my first post here, althouth following for a while and into simple living, permaculture, degrowth and community living for some years

We already made some "post in the ground" constructions (mostly with eucaliptus) because we needed some sutructures fast (and are mostly a group of urbanites without much knowladge) right now we are planing to rebuild a very small water mill ruin to make a tiny house for me and my partner, the idea is to add a whole floor with a high celling for a bed and keep the lower water mill floor separated (for small workshop or to store stuff as there are no windows),

we already read some books about timber framing and also about roundwood timber

i have loads questions and ideas (mostly nonsense probably) this one is about the kind of wood we plan to use.

we live on north coast of portugal and Acacias (known here by "mimosas") and Eucaliptus are a big plague, taking space for local trees to grow, spreading fire fast and destroying biodiversity, living just next to a (long time abandoned) man-grown forest of eucaliptus and acacias (many native oaks, willows, platanus, etc already with a couple dozens years growing in the middle of overgrown eucaliptus and 20/30 years acacias

from timber related australian websites (as both acacias and eucaliptus are native from there...that was my reasoning) i see references for the use of both timbers with structural and architectural internal use: http://www.woodsolutions.com.au/Wood-Species/silver-wattle

eucaliptus fibers are not so straight as acacias and most of the ones near are already overgrown to be practical to move them - the idea is that most of the work is made by us two - first reason for it to be small - so we think of mostly use acacias for beams and posts for braces we can use some pruning from native oaks if needed

my main worry is about "checking" as we already noticed eucaliptus and acacias suffer a lot from that - we are working most of them green (althouth we have a couple already cut from last winter that we still didn't try to make joints)

i've seen it written that most problem about checking is about aestetics, when should i be worried about structural affect?

i will try to upload a picture of the first joint we just finished yesterday - today morning was checked :-/

and to write another post about the ideas we have - we've been planing slowly last summer and this winter and a lot is still only on our heads

I don't know about acacia wood, but I've had experience with eucalyptus. It is very hard to split when wet, but much easier when dry. Checking results from uneven drying. You may reduce that by sealing the ends (so they don't dry faster than the middle).

If you have the patience, you can try curing the poles by painting the ends and any cut branch stubs with oil and then putting them up under shelter and let them dry for a year. This is how you cure tool handle poles without cracking. Then take them down and peel them. But poles are much easier to peel when green! I think small cracks with the grain are harmless for the most part.
Another way is to handle them as one would bamboo, and simply not rely on penetrating the wood with any kind of fasteners (nails, screws, bolts, wooden pins, complicated joints). Use wire or twine and tie the poles together, and fasten sheathing to the frame by drilling holes in it and tying it to the frame. Small poles can even be bundled for more strength.

we are no-budget constructor... working mostly without powertools have a dozen of recovered, 2nd handed and lent chisels (will try to post a easy-cheap solution for sharpening chisels that we used, they are all cutting prowdly )

i just read in many places (funny i can't recall ben law ever mentioning that on the book except the wood-tar he mentions on sealing the end of the posts that touch foundation) to seal the ends to slow down drying, it makes a lot of sense, specially knowing the checking happens more on the center of a log, using roundwood timber i can imagine is very hard to avoid checking.....

what is wood-tar? how to make it?

would wax work out? and parafine? (we can skip a lot of parafine [and probably mixed wax] from the local cementery garbage containers)

lin seed oil would be suficient? and burnt car oil (the local farmers nowadays "tradition" to treat wood - it worked quite well on preventing rotting on some exposed wood on our woodshed)?

Use whatever you have readily available that might slow down the evaporation from the cut ends. Experiment to see what works best for you. You can cut your logs long, seal the ends and then recut them to size when the logs are dry.

Some more resources:
http://www.wood-database.com/wood-articles/drying-wood-at-home/
http://www.builditsolar.com/Projects/WoodDrying/wood_kiln.htm

Hi J.T.

Welcome to Permies.com...

my main worry is about "checking" as we already noticed eucalypts and acacias suffer a lot from that - we are working most of them green (although we have a couple already cut from last winter that we still didn't try to make joints)

Working wood green is the standard in the world of traditional and natural architecture and woodworking...It is more myth than fact that wood must be "dry" to be turned into useful objects from bowls to Timber Frames. So you are just fine...in general with what you are trying to do...

i've seen it written that most problem about checking is about aesthetics, when should i be worried about structural affect?

Seldom to never...98% of the time, and when they are an issue it is so obvious that you couldn't miss it...Like we just had a really pretty grained Ash timber split in half..So we will now use it for some other smaller timber needs...

what is wood-tar? how to make it?

Pine Tar Oil is difficult to impossible to make for most DIYers...It can be purchase if that is the way you choose to go.

would wax work out? and paraffin? (we can skip a lot of paraffin [and probably mixed wax] from the local cemetery garbage containers)

Avoid paraffins these are nasty and most are petroleum based with other toxic gick in them...

lin seed oil would be suficient? and burnt car oil (the local farmers nowadays "tradition" to treat wood - it worked quite well on preventing rotting on some exposed wood on our woodshed)?

DO NOT use car oil...very toxic and some have heavy metals in them that will pollute ground water. Flax oil (linseed oil) if of the correct type (not adulterated with chemical driers and other toxic gick) are what we use blended with other natural ingredients.

Timber framing is an ancient craft that relies on all wood joinery and not lashing methods (a different kind of mindset and joinery system.) If you have more specific questions, I would be glad to answer them...

thanks for the answers
i'll try to post more about our project soon...have some drawings, pictures and questions

just read somewhere that most of the woods can be used for timberframing, is that right?... still couldn't understand quite well the diference from hard and soft wood.... read somewhere that acacia is a hard wood...

i imagine a willow tree to be soft wood (am i mistaken?)... we have some pretty big and not so curved old willow trees that are to heavy to hold themselves to the ground (i imagine they are over 40 years thought i don't remember if i ever counted their rings... they are over 30 cm wide) and started falling slowly for 3 years, we are cutting down some, as they start to look as to endanger someone or some structure/garden (althouth they are falling quite funny, so slow till they touch other tree or the ground.... that wood is wonderful to carve, shape, cut anyway... but my reasoning about lack of information on willow for construction makes me think it's not that good for structural.... am i wrong?... there are some pretty straight that could be used for vertical posts....

J. Tabordy :There is a fair Wikipedia article about Pine Tar Which does contain creosote, which is regarded as a carcinogen ! a Google search looking for information
on how to make ''Stockhom Tar'' should lead you to related articles, and a discussion about the frequency of massive earth moving explosions from the techniques
of our ( North American) Colonial past

Basically If it loses its leaves in the fall its a hard wood, if it keeps green leaves(needles) through the winter its a soft wood ! Willow is one of the softest of the Hard
woods, It is subject to loosing limbs and that lets in rot, IF an unlikely IF, you could find a piece straight enough to use, and not rotted, a 2 Xs diameter piece of
willow might be used as a prop timber, I would never use it for a building timber myself, but I have many more choices than you

Read up on coppicing and pollarding, there is much information on this subject that will 'give you a leg up ' For the Good of the Craft ! Big AL

Basically If it loses its leaves in the fall its a hard wood, if it keeps green leaves(needles) through the winter its a soft wood

nice reasoning, but does it apply to non native trees as well?....on the australian website i posted before they refer to Acacias as hardwood (and at least here their leaves stay all year)....

i can't find a place to buy this pine tar or wood tar here....just creppy chemical stuff... i've used parafin on the beams i already cut, because that's what i had on hand (form cemetery dumpster...maybe some real wax mixed in as well)...i will try to find bee wax for sale as it seem the best ecological/health choice...

it looks like it's working as it stoped cracking (the cracking was visible to grow within a day in some of the beams and stoped when we coat the endings with parafin....

i'm completly in favor of "anything you buy should be the most healthy for the planet as possible" but i'm also very keen on using reclaimed stuff over buying...but the parafin we have is finishing and instead of a journey to the dumpster i will buy a couple of kilos of wax...although on small shops they were also just selling parafin....imagine in the big city there will be more choice...