Junkwood Timberframing?

I would be hesitant to use more than a few of the larger red pine, and be sure to debark it first. It rots fast, and with the clusters of big knots has weak spots every couple of feet. Birch also rots fast especially if not debarked. I don't know about poplar, I have the impression it is more durable than aspen which can turn to punk in a couple of years and is weak to start.

Glenn Herbert wrote:I would be hesitant to use more than a few of the larger red pine, and be sure to debark it first. It rots fast, and with the clusters of big knots has weak spots every couple of feet. Birch also rots fast especially if not debarked. I don't know about poplar, I have the impression it is more durable than aspen which can turn to punk in a couple of years and is weak to start.

Sorry, getting my latin mixed up, it looks like I predominantly have quaking aspen, not poplar, breaking into the red pine stands. So apart from the maples (which I'm not going to cut myself), it is basically just the red pine, like it or knot.

Glenn Herbert wrote:
Diagonal bracing on the horizontal plane as you describe would not do much; the metal roofing screwed to the framing will keep the deck square. The issue is the walls leaning, and at least one diagonal brace on each wall is what will help there.

Would the stacks of cordwood take care of this? I stacked the 'demonstration' wall with them all pretty close to an inch from the wall pallets. That will allow air to circulate for drying and give an indication of the building starting to drift if the gap goes away on one side, but still prevent a collapse I'd think. Then again I've never tried to push over a full face cord all at once...

Back from the PTJ and the mosquitoes are thinning out enough I can get some oxygen mixed in with them each lung full, so I'm back at this. A deer commited suicide by radiator with my truck so I don't have a way to pick up the purlins, but am half way done with the rafters:



I've made notches in them so that they sit flat on the top of the pallet on the lower wall. I'm planning to put one or two screws straight up through the pallet into the rafter there. The notch on the outside of the wall will keep the rafter from moving inward, would I want the notch to go in a half inch or so to straddle the pallet and keep the rafter from sliding outward?

The top of the rafter is 3+inches thick where it rest on the taller wall, but don't want to notch it to rest as that is my minimal thickness already. Would a simple screw through the pallet into the rafter there be good or would I want some sort of notch/shim to make more solid contact?

Reflecting more on the support notches, I think I want to make them deep enough so that the remaining material is 4". This would roughly retain the 2:12 slope on the top side of the rafters. I might need to shim up the top mount point to level off the ones that are closer to 3" than 4" up there.

I decided on 10 rafters. They will be 16" on center, leaving the outer ones 10" from the edge of the roof metal. They are 14' 6" long to leave 3" to the edge from the tips if I mount the purlins there.

I'll be using 1x3s for the purlins, 8 of them spaced 24" on center. This actually should leave 4.5" to the edges top and bottom instead of 3", not sure if it would be better to bump those out slightly. They will be 14' long to match production length, meaning 6" of unsupported metal to the sides. It doesn't seem worth buying 16' boards and cutting them down for that extra support. The purlins should extend 4" past the center of the outer rafters.

Attached are some establishing shots, rafters placed temporarily to size up the situation...

I think it would be better to screw or nail down through the pine rafters into the hardwood pallets.  Screwing up into the soft pine may not be as strong since the threads could strip out.  If needed, or maybe it would even be more ideal, to use two fasteners and toenail the rafter down to the pallets.

Also, the purlins don't need to be single pieces of wood.  You could butt together 7 and 8' pieces to get the 15' I believe you're hoping for.  Where they meet just splice them together with a hunk of wood and some screws.  Or go with 10' boards and cut some in half to have 5' and 10' pieces.  Then alternate the layout so the joints will be staggered.

Mike Haasl wrote:I think it would be better to screw or nail down through the pine rafters into the hardwood pallets.  Screwing up into the soft pine may not be as strong since the threads could strip out.  If needed, or maybe it would even be more ideal, to use two fasteners and toenail the rafter down to the pallets.

Going up through the pallet, the 3.75" screws i already have could put 2.25" of thread into the pine. Going the other way, I'd need to find 5.5" screws, and they would only have 1.5" of the pallet to grab with the threads. Would i want to sink the securing hole onto the rafter and use a shorter screw?

I need a quick non timberframing lesson in screws. When is it okay to have threads in both pieces, and when would one want the smooth top of the shaft to be at least as long as the outer/top piece? I've noticed the latter leverages the pieces together better, but never heard an elaboration on it...

Coydon Wallham wrote:I need a quick non timberframing lesson in screws. When is it okay to have threads in both pieces, and when would one want the smooth top of the shaft to be at least as long as the outer/top piece? I've noticed the latter leverages the pieces together better, but never heard an elaboration on it...

You won't believe where I got this lesson from... a surgeon!

1. The first hole the screw goes through should be a "pass through" hole. It needs to be the same size as the outer size of the threads.
2. The second hole (second piece of wood) needs to be the diameter of the core of the the threaded part of the screw, or maybe a little less if it's fairly soft and fairly fresh.
3. Thus, when you screw in the screw, it passes easily through the first piece of wood, then grabs the second piece and draws it firmly against piece one. If there are still threads in piece one, that's not a problem because they're not grabbing anything because the hole's too big for them to grab the edges.
4. However, you need the two holes lined up, so normally, I would use a small diameter drill bit, and drill through both pieces of wood deep enough for the screw or at least as deep as you can get if your drill bit isn't long enough. Then I separate the two pieces of wood and use this small "guide hole" to drill the properly sized holes for each piece.

Why did I hear a surgeon teaching this lesson? Because a patient's broken bone hadn't healed properly despite a surgeon putting  a screw in it, because an inexperienced surgeon hadn't followed the above procedure and the screw was actually holding the two pieces of bone 1 mm apart - that's all it took to not heal was 1 mm! It had looked OK from one angle, but the Xray showed a different angle that showed the gap.

So it's the same with your rafters - you want the screws to draw them against the pallets and not risk any gap. I would think that sinking the securing hole would work, but are your screws flat heads or round heads? Have you considered using nuts and bolts or is that not recommended in these sort of housing situations? (the bolt head could still be counter-sunk.

I guess it depends how solid your pine rafters feel.  If they seem like they'll hold the screw threads well, going up is probably ok.  I was thinking you could toenail them.  That means you angle them in from the side so 2.25" would be going diagonally through the rafter and the rest of the screw would be in the hardwood.  One from each side should be enough, unless it doesn't feel as strong and then ignore that idea.

Jay's spot on.  Terminology wise, the smaller hole is called a pilot hole and the bigger one a clearance hole.

One added detail...  If the screws have a long section that doesn't have threads below the head, and it's roughly the same diameter as the shank (that the threads wrap around), and it's fully within the first piece of wood, then you don't need the clearance hole.  For instance, with the screw below, if your first piece of wood isn't thicker than that bare section of the screw, you can just drill a pilot hole through both pieces.  When the screw threads are fully into the second piece of wood and not in the first, they'll suck the screw head down tight since that bare shank can slide through the pilot hole.



If that threadless shank part is as big as the threads (below), then you might still want to clearance hole it.  Especially if you're worried about the first piece splitting.

Coydon Wallham wrote:Reflecting more on the support notches, I think I want to make them deep enough so that the remaining material is 4". This would roughly retain the 2:12 slope on the top side of the rafters. I might need to shim up the top mount point to level off the ones that are closer to 3" than 4" up there.

I decided on 10 rafters. They will be 16" on center, leaving the outer ones 10" from the edge of the roof metal. They are 14' 6" long to leave 3" to the edge from the tips if I mount the purlins there.

I'll be using 1x3s for the purlins, 8 of them spaced 24" on center. This actually should leave 4.5" to the edges top and bottom instead of 3", not sure if it would be better to bump those out slightly. They will be 14' long to match production length, meaning 6" of unsupported metal to the sides. It doesn't seem worth buying 16' boards and cutting them down for that extra support. The purlins should extend 4" past the center of the outer rafters.

So my notes were messy, i kept updating as my materials developed and ended up using the wrong iteration. I assembled the rafters at 17 on center only to find they should be at 18. I just did 1 screw from the bottom to secure them, do it was easy to correct. I've tried toenailing them but it only works on the larger ones i had to cut a deep notch into to match the height of the smaller diameter ones.

The bottoms of all the rafters are 3.5 to 4 inches thick at the top of the wall. The tops are 3 to 3.5", though i had to cut a half inch notch into one to keep it from sitting too proud. Since they aren't perfectly straight, the minor variations don't matter in making a flat surface- I just leave as much material as I can. I am counting on a bit of flex from the purlins as well as shaving and shimming the rafters as needed.

I arranged the rafters in order by eyeball to make irregularities in height match close to each other. Some of the earlier logs has bits of bark that i missed at first. When i picked them off now i found a couple larvae hiding underneath.

Next step is the purlins. I know using pallet wood has been mentioned as an option, but this is dragging on to long and I'd like to finish up with dimensional lumber so i can move on to projects needed for winter. I pulled out a 1*3 i have and am wondering if .75" wood is enough to secure the roof?  

Turns out 8 purlins @ 24.5” on center will fill the 14.5' length of the rafters perfectly. However the roof length is 16' so there will end up being 9" unsupported top and bottom. Guessing I'll have to figure some sort of extension to the rafters now.

Well, the job is looking good now.
I will never be able to look at a broken leg again after J's little lesson on screws!. I cannot unsee the issue.

John C Daley wrote:I will never be able to look at a broken leg again after J's little lesson on screws!. I cannot unsee the issue.

John C, I'm sure you're so experienced with building that you've long figured it out. But a friend of mine who was helping we with a project *insisted* that he didn't need to follow the surgeon's instructions and now I need to re-do a bunch of stuff. If a broken leg reminds someone less experienced just why we use screws the way we do, I'm good with that! It was nice that Mike Haasl came along and put some more technical names on things, but for some of us, remembering things is based on understanding the "why" and having a good picture!

Jay Angler wrote:

John C Daley wrote:I will never be able to look at a broken leg again after J's little lesson on screws!. I cannot unsee the issue.

John C, I'm sure you're so experienced with building that you've long figured it out. But a friend of mine who was helping we with a project *insisted* that he didn't need to follow the surgeon's instructions and now I need to re-do a bunch of stuff. If a broken leg reminds someone less experienced just why we use screws the way we do, I'm good with that! It was nice that Mike Haasl came along and put some more technical names on things, but for some of us, remembering things is based on understanding the "why" and having a good picture!

I just hope your story wasn't meant to instill a greater confidence in the standard practices of western medicine- I've often thought that the only ailment I would trust a "doctor" to treat would be a broken bone and now you have me questioning that.

I had some pictures with all the rafters in place, now that phone died...

My truck has been at the body shop over a month and they don't seem to be in any hurry to fix the deer hole up front, so it seems it will end up being most expedient to cobble up the purlins from my scrap pallet wood after all. I was counting on the longer boards to help produce a more level surface for the roof sheets, but i guess minor undulations won't have a functional impact. There will be more spans between rafters not supported by whole boards, will screwing in short connector pieces to the boards from underneath provide the same support?

Anything else to watch with pallet wood up there?  Many of the boards i have are splitting along the grain near the ends, but seems they are strong enough along the grain if the screws hold.

Short connectors would definitely help.  If you have the wood to spare, bridging the rafter gaps with whole pieces of pallet wood would be even better.  They don't need to be in a continuous line, you could jog up and down as the pallet pieces travel across the roof.

Mike Haasl wrote:Short connectors would definitely help.  If you have the wood to spare, bridging the rafter gaps with whole pieces of pallet wood would be even better.  They don't need to be in a continuous line, you could jog up and down as the pallet pieces travel across the roof.

Nice CAD work, or is that done with blender?

I'm concerned about doing it that way because it would make for involved logistics in finding the Purlins with the mounting screws. If the ends of the main row were extended to meet each other and the adjacent piece still placed to span the rafter for support, with the screws all secured in the main row, would that provide a solid mounting?

Sure, screwing into one continuous row with a bracing/support board adjacent to it would be just splendid

I like the solutions so far.

My thought was that if you've got enough free pallets, I'd manufacture long pieces by using a double thickness of the pallet boards screwed together until it matched the whole width of the roof. It would be twice as thick + screws = heavier, but would that be an issue? If you ever have to walk on the roof to clear the snow, the extra strength would be an asset. If it were me, I'd actually glue and screw the wood together into a home-manufactured beam, but using not too nasty glue.
I'd also make sure they started/stopped in different spots for adjacent purlins so you don't get a weak point.

Would that be stronger or weaker than Mike's suggestion? Maybe a little weaker?

I think it would be stronger as double board beams. I'm not using glue when there is a reasonable alternative, but even just the screws should work.

It would use the most boards. I'll inventory what I have. It might be worth the extra work, but my initial guess is that just single hardwood boards across the 18" rafter spacing would support a snow load. Most of the pallets come with 17-23" spacing between supports. If a few of the boards come from old/brittle wood, the rest should hold and allow any breakage to be braced before further damage occurs.

I've hung from the rafters also- any two can support 200 pounds with a slight bounce...

I ended up using up some scrap 1x lumber for half the purlins, anywhere from 1x3 to 1x10, and scrap pallet planks for the rest. Single rows across felt plenty strong. The resulting surface has proven dance worthy, even under soggy conditions...

Congratulations on getting the roof on! What a great-looking building.

As for bracing the walls on the interior, I'm thinking 45*s would be the most efficient- any threshold lengths to a brace where I'm wasting material or losing strength? I was thinking going from the top corner of each wall down 45* to the floor but it was opined that shorter pieces would work just as well.

My suspicion with pallet walls that are screwed together, is that the biggest risk of bowing/shifting is the joints where the pallets meet.  So I'd be bracing the walls from top to bottom in a few spots to keep the middle of the wall from bowing in our out.  Also along their length as well.  Maybe you did this already?  

As for diagonal bracing, I think the pallets will prevent racking pretty well.  For those who don't know, these are much much beefier pallets than the normal shipping pallets.

Mike Haasl wrote:As for diagonal bracing, I think the pallets will prevent racking pretty well.  For those who don't know, these are much much beefier pallets than the normal shipping pallets.

That would make a big difference. I've got a stack of very wimpy 6'x30" pallets to make some more raised beds, but have stalled because I need a helper to wrench them to approximate squareness and then hold while I get some more material on them to keep them square. Not all pallets are created equal, and I've definitely got pallet envy for the stash Coydon has access to!

Mike Haasl wrote:My suspicion with pallet walls that are screwed together, is that the biggest risk of bowing/shifting is the joints where the pallets meet.  So I'd be bracing the walls from top to bottom in a few spots to keep the middle of the wall from bowing in our out.  Also along their length as well.  Maybe you did this already?  

As for diagonal bracing, I think the pallets will prevent racking pretty well.  For those who don't know, these are much much beefier pallets than the normal shipping pallets.

wouldn't a diagonal brace address bowing in or out at the same time? To clarify, I'm thinking of placing 2 x4s where the orange lines are in the following pics. My original thought was something like the green line in the last but a comment above said that sort of racking wouldn't happen...

Coydon Wallham wrote:wouldn't a diagonal brace address bowing in or out at the same time?  

Yes it would, might still want something to make sure the top of your long walls don't bow in or out (since the yellow braces meet down at the bottom).

As log as the tops of the walls are fastened securely to rafters, rafters to purlins, and purlins to roofing, the roofing will prevent the tops of the long walls from bowing in any direction.

Sticking with the use-what-you-got theme, I have a bunch of junky 2*4s around 90" here. To brace the walls to near the tops calls for about 120" ones. I have a couple 144"ers but don't want to cut them down for this. I'm guessing Any brace that goes more than halfway up will be fine. The shorter ones will secure less of the pallet seams though. Would the difference be worth waiting to buy some ten footers for? I could also do the twelve footers more shallow than 45* at full length if that would be worth it...

I think that one of the coolest pallet buildings ever

John F Dean wrote: If it were my build, I would be concerned about those pallets in contact with the ground rotting out in a few years.

Was this issue ever addressed or did the original poster decide to accept that his structure would rot into the ground in a few years?

Someone mentioned concrete blocks. That would help some but the hut would would still shift around from frost heave.

When building a shed roof it's best to face the low end of the structure toward the dominant direction of incoming storms. This way the roof protects the most vulnerable wall. Long roof overhangs protect a structure. Any wood exposed to the weather in northern climes will soon rot.

Tom Allyn wrote:Was this issue ever addressed or did the original poster decide to accept that his structure would rot into the ground in a few years?

Someone mentioned concrete blocks. That would help some but the hut would would still shift around from frost heave.

When building a shed roof it's best to face the low end of the structure toward the dominant direction of incoming storms. This way the roof protects the most vulnerable wall. Long roof overhangs protect a structure. Any wood exposed to the weather in northern climes will soon rot.

The shed is built with pallets directly on levelled ground. My goal was to have dry storage space ASAP and to learn some basic building techniques. If it lasts 3 years it will have given me time to build some other things. I will transfer the stuff into them and throw the rotting wood from this building into a hugel or burn it in a rocket mass heater (it is all marked as heat treated). The screws can be pulled out and most reused. The roof panels can go on another building(s). The rafters should still be nice, long, smooth timbers for another project. With what I learned putting this up, my next building should go up in a fraction of the time. I think there is a fair chance it will still be serviceable in 5 years as the ground is very sandy.

I haven't been to the property in a couple months, but before I left, the building was standing solid. I have yet to fill most of the overhung space with cord wood, but the structure as is has remained dry inside during rains. Even blustering snow has barely made it under the eaves and past the pallets to the interior. The ground had frozen solid for the season while I was still there and I hadn't seen any signs of shifting from frost heave. I'm guessing frost heave is reduced if you have well drained ground?

The one big flaw I've found is that the drip line from the lower roof edge falls an inch onto the foundation pallets there. This causes roof run-off to splash onto the cord wood and saturate the pallet wood under it. I could have assembled the roof a few inches over and had the drip line completely off of the pallets if I had anticipated this. I do have some old, discarded gutters I can reshape and mount there to fix it when I have some time.

Prevailing winds are from the West here. The low end of the roof faces NW because there is a service road coming from that direction with dense trees directly to the West and South...