hello, got to restart on my old cottage renovation, some stonework has been done and its time to start collecting material for the roof , existing beams are really bad so whole roof to come off and i have decided to make the attic space as extra living area, this means a timber plank floor to be laid on top of some round pole logs, heres my question, i have mostly or maybe only sitka spruce logs to work with ,and was thinking of cutting a single flat  surface to each log---spanning a 20 foot wide space--wall to wall--i can get to choose fairly substantial logs to work with ------but i have no experience of working with round pole sitka and i am beginning to wonder if just taking a single flat cut will lead to warping or twisting---cant find any thing on the web about this , hopefully someone has had some experience of working with sitka ---thanks

tony uljee wrote:hello, got to restart on my old cottage renovation, some stonework has been done and its time to start collecting material for the roof , existing beams are really bad so whole roof to come off and i have decided to make the attic space as extra living area, this means a timber plank floor to be laid on top of some round pole logs, heres my question, i have mostly or maybe only sitka spruce logs to work with ,and was thinking of cutting a single flat  surface to each log---spanning a 20 foot wide space--wall to wall--i can get to choose fairly substantial logs to work with ------but i have no experience of working with round pole sitka and i am beginning to wonder if just taking a single flat cut will lead to warping or twisting---cant find any thing on the web about this , hopefully someone has had some experience of working with sitka ---thanks

I don't think so.

I am no real expert with round wood building though. I have built one round wood building, and it was really rugged, enough so that a few years later I dragged it literally up the road by a half mile. And here in Maine we have Spruce, but it is White, Red and Black, but not Sitka Spruce. Still, Spruce has the most strength to its weight of any wood.

Here. where buildings go back to the 1700's, it is pretty common to see single-slabbed beams with significant strength with no warping. They did this a lot because chopping 4 sides with an axe was tough work, and often not required for the spot where it was going.

It would have to be pretty big to span 20 feet, but I don't think slabbing one face off will be bad.

thanks, i was kind of dithering around on this --and if i dont move on this project and the round pole timber thats available --its going to stall and putter out ---the trees are down and destined for  cutting up and chopping for heating in woodstoves---they are fairly substantial in girth and will be spaced to 48 inch centers--only supporting the timber plank flooring and not the roofing rafters in any way---if i can source from the same location some decent length and strength for a center beam-- with a few columns --i would go for that-- the bigger and more of ---as a belt and braces approach.

I have nothing against roundwood buildings, it is just that we have always had sawmills here so for me it is easier (and takes less trees) to saw logs into framing lumber and build semi-conventionally. Again I fault no one for using what that got.

I have chopped beams by hand though, and got pretty fast at it. Mine were White Spruce, and at 8x8 inches, and at a 12 foot span, my calculations were, that it would support 4500 pounds. That is quite a bit of weight! you should be around the same with a partially round beam. Mine were for the interior timber framing holding up the roof.

I wish others had chimed in though that were more educated at this than I am. I felt bad that you had no replies and thought I would offer up what I could. Sorry it is not much.

My hand hewn beams...

what you have given has been helpfull and at least gave some ideas ,i would have gotten to an answer in the the end --just a bit later  maybe --but what you gave -- got my thought process on the right direction, i have goggled up some stuff on beam stress calculations again  ,and the pictures are great help too, i have to work with what i have to hand and with what i can cobble together machine wise , i will need to build a simple long enough steel ladder frame on legs and slide a chainsaw along it to cut a flat face off each log---looking at the workshop section on the forum gets me dreaming away---i have an old stick welder , a small grinder and large grinder, hand drill and hammers ,and selection of hand made chisels plus spanners,and a small home built forge and anvil,  thats it really but i have managed to build my man-shed , my teleporter/telehandler s shed , a bucket ,boom and a mixer for that as well , 2 car trailers, car ramps , nissan hut shed roof trusses, several woodstoves ,my own kitchen range cooker, all the beds and some furniture plus several projects /repairs for friends ---but hand hewing beams ---hats off to you for that, cheers ,tony

What is the reasoning for making one side flat from end to end? Is this for the interior side? What type of Joinery are you planning on using or are you going to use steel joins?

Round wood roof joists of Sitka Spruce will be very strong with little flex if left round except for where the joinery is worked, flatting one side will introduce a slight possibility for some flex under snow load, that will depend mostly on the diameter of the log.
If you use scribed joinery the structure would withstand just about any thing Nature can throw at it.

I am sorry I hadn't seen this when you first posted it, but if you give me some more information on how you plan to build, I'll give all the help I can.

Redhawk

thanks, cottage is 21 feet wide outside to outside walls , walls are 30 inches thick--each side---and its 63 feet long---with a simple A framed rafter roof --its been around a long time so has had several hundreds of years of running repairs , some fairly horrific , but its still here and standing, i have no intention of demolishing any walls or hacking them up any further than they have been already, but the house is too small for us , the existing roof timbers are very old and a mix of hand cut and old  rough sawn timber planks ---all small sizes--no big majestic single log stuff here--and its all full of wood borer. So to solve several issues , going to strip off the entire roof and make up new rafters in a gambrel style --to create an entire full length and width(almost) top floor space with lots of headroom, which can then be divided up into some bedrooms and a bathroom/ toilet. So the plan is to span the width with round pole timbers ---spaced at 48 inches centers and lay plank on top of it as a new floor area---it wont be supporting any roof loads . Would have to bring each pole up to level and thus have a single back cut along their lengths to achieve this-- have had some experience with gum tree poles and they dont take  kindly to this idea ---they split and twist  quite a bit ---so hence my question --as i have very limited hands on/working knowledge of sitka spruce in its round pole---would they tend to do the same or stay stable .thanks