How long does it take for non treated lumber to degrade?

Started by Adam Roby, April 04, 2014, 05:38:10 PM

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Adam Roby

I have been rethinking my cabin plan ideas, and am now leaning towards a 12x16 or a 16x16 with a loft area.

My main problem (other than money and the lack of land) is the time it takes to build.  There is no way I can dry in within a single summer.  I was originally thinking I could potentially build all of the framing with pressure treated lumber.  Start off with a deck the first season, then a roof the second season, and finally close it all in on the 3rd season. 

Then I got to wonder... other than wood that is in direct contact with the cement or very close to the ground, and if it is only conventional lumber (no plywood or OSB), would a non treated 2x hold up for 3 years in the rain without rotting or otherwise losing its strength?

If I were to build a structure without a floor, walls or roof, just all of the framing... would it hold up?  Figure it does not have the plywood to keep things straight but at the same time it does not have plywood that acts like a sail with the wind, nor will any snow accumulate on the roof if there is no plywood up there.  Would just the stick frame stand up over time allowing me the time I need to complete a build?


Don_P

No, it will not hold up in most climates. Dry it in in one fell swoop. Build the foundation and stop. Then muster your resources and run for the roof. It's quite do-able  :)


Adam Roby

Hmmm... I just did some quick calculations and it would only cost an additional $297.14 to do it all in pressure treated.  I am starting to see some light at the end of the tunnel.  :)

jsahara24

I would beg my friends for help!   You want to get a roof on and tyvek up in one summer season!

Sent from my XT907 using Tapatalk 2


Don_P

I'm not real enthusiastic about your timeline. This frame above is a good start, I like the basic concept but there are some details I'd change. The main and loft floor girders cannot be hung on the sides of posts. They either need to be notched into posts, supported on jack framing or hung with hangers rated for the loads. The floor joists need rim joists to hold them upright and I'd install a row of blocking over the mid girder between joists to help them season as straight as possible.

The top plates need to be replaced by a beam as they will sag without studding. There needs to be some diagonal bracing, this is usually provided by sheathing, but if it's not there, bracing either permanent, or it could be temporary until future sheathing is installed, needs to be installed.

The gable end top plates create a hinge in those walls, there should be studs running uninterrupted from the loft floor to rafters. Studs should run from the lateral support created by the floor and roof diaphragms and should not be broken where there is no lateral support, it also makes the framing easier. The studs do not need to be installed at this point as long as there is diagonal bracing. I'd block between each rafter over the outer wall, leave that blocking 1 to 1.5" lower than the top edge for future ventilation.

Common nails subjected to cycling moisture are derated. Hot Dipped Galvanized ring shanks or spirals or Ardox nails will retain their strength and resist the corrosive effects better. Rather than a nail gun I'd use a palm nailer and hand drive nails.


flyingvan

I'm not crazy about surrounding your living area with copper naphthenate.  Pressure treated lumber is pretty crappy, around here at least---seems they take the inferior pieces with lots of knots.  Your place looks small enough to throw a tarp over


Find what you love and let it kill you.

Don_P

Our big boxes buy the cheapest treated they can. We do get some nice treated from one supplier locally, he specifies #1 when he orders and is the "go to" guy for treated. But, it doesn't thrill me either, our treated is ACQ but I'd rather not be the guinea pig. An alternative would be borate treated, that does leach out though, maybe a water repellant finish to slow that down and then the tarp. This is really small enough to be framed and dried in quite quickly. If time is the problem it might be better to sub out the shell.

MountainDon

#7
FWIW, I managed to take our 16x30, from a bare but ready foundation to dried in without doors or windows in about 2 weeks. That was working from a pile of materials delivered to the site by the lumber dealer almost entirely by myself. But working virtually every day, one day after the other. Another week and I had the door and windows in and flashed, all walls and roof covered with building felt. In that space of time there was likely some time taken away to return to the city. I don't recall exactly how many. Mostly I was working. There was some rain that slowed a few afternoons.

I did spend time, a lot of it, planning. I used papers and pencils to draw everything and spent hours mentally assembling the components.
Just because something has been done and has not failed, doesn't mean it is good design.

Adam Roby

Thanks everyone for your feedback.  I will be redoing the drawing and reconsidering the options.

Don_P - I would like to look into what hangers exist for the loft and main floor as well, I would not trust just attaching them on the sides like that.  The main reason I wanted to have the 4x4 posts run from the pier to the roof was to help with stabilization so that the building does not fall off the piers. (The scissor effect thing).  I will add blocking to the design as well, especially if I don't sheath the first season I need to keep the floor joists from bending and drying out of shape.  The drawing has the bare minimum drawn in, but for sure all the walls will be studded before any sheathing goes on.  (I wanted to get a frame in a standing position with only treated wood, but without costing a fortune).  The top plates will have studding beneath then before any sheathing goes onto the walls or roof, to help support that load.  I do need to consider some cross bracing however, especially if I want to put a roof or even tarp since that will mean a snow load as well as some wind resistance.  I will add to the drawing with all of your recommended additions and redo the cost analysis.

flyingvan - I too am a little worried about this.  I wonder how much this could leach into the living space... something to consider for sure.

MountainDon - I want to have every single measurement factored in to the 1/16 of an inch if possible way before the first piece of wood is cut.  I too am a stickler for the details.  SketchUp is a great tool to help with that.

Time line:  Here are some very basic facts that contribute to the timeline problems.  I have a 4 year old daughter, and my wife works weekends and evenings, so I am very much like a full time single father.  I am with her 24/7/365.  This limits my building in a very big way, but I would like her to enjoy "helping" me and being in the woods, I think it would be a good childhood memory for her to have.  I also have 3 herniated discs in my lower back and am often in extreme pain.  Some days are good, most are bad.  I have been waiting for 16 months now for the "specialist" to decide if I will get surgery or injections, or something else to help with the pain.  Because of this, I have to take it very easy.  I may be able to dig 1 hole and fill it with cement in an entire weekend.  I can't work 12 hours a day anymore, so I need to be as realistic with myself as possible, and plan it so that my timeline allows it to take years to complete.  Friends are simply not reliable enough, nor do they follow my standards of building practices.  (I am pretty finicky and want "perfection").  I do want a cabin, but mostly I want to be building a cabin.  That is the fun part for me.


Don_P

I hear you, I always assumed I would gracefully keel over mid furrow and they'd just hitch up another mule. Happily they don't dock you for damage on return  :D. Obviously I like the continuous posts. I wouldn't notch a 4x4. A simpson HUC210-2 is good for 2680 lbs with a double 2x10 in DF/SP in souble 2x8 that same series is good for 2085 lbs, I haven't looked at your floor loads but that would probably get it.  These are concealed hangers ( the ears turn inward so they could mount on the post face). A strap across from girder, across the post to the next girder would provide a good tie. The floor and wall sheathing will likely eventually do that as well. Go ahead and do the same thing under the top plate to carry the rafters, that will sag immediately under just the weight of the rafters with a double 2x4 flatways. This also takes the load off the floors and puts it onto the posts. The beams at each level then collect the load from each, the roof, the loft, and the main floors and deliver them to the posts independently rather than collecting the loads from 2 or more levels and delivering the accumulated load to the hangers on a level below. Essentially each level is bridging its' load over the level below to the support columns. Loads/spans/species/grade determine the member sizing, we can walk through all that if you need help.

By the time you get ready to close in the interior the treated will be quite dry, it'll accept a seal coat of paint to help isolate you from the treatment if it's a concern.

hpinson

How do building departments/ inspectors look on extended timelines by home builders? 

I am in much the same position, very limited availability to work on a cabin project, some minor health issues, and I can easily see my build going over several years. This is one of the main reasons I have not taken action to date in terms of submitting a plan for approval to my local building authorities. I just am not able to commit to finishing in six months (like I understand is the requirement in my home town), or a year.

I so much would like to be able to approach this at my own speed, not be under time pressure, but that does not seem to line up with the approval / inspection process in the US, at least as I understand it, where everything is geared to contractors getting the job done ASAP.

Thoughts on this?

flyingvan

It's probably unique to your jurisdiction.  Here, I had three years from the time the building permit was approved---extensions weren't difficult to get but were expensive.  I had two days to spare, most of the slowdown was due to weather.  But really, the time between foundation and dry-in doesn't represent most of the build and shouldn't take too long
Find what you love and let it kill you.

Don_P

It is very much jurisdiction dependent. Some require extensions and charge mightily to keep things moving along, others don't care. I've gone on for 3 years on a large project with no extensions or problems. I had a helper have to pay another permit fee after 6 months, and everything in between. Always get an inspection at least once every 6 months to avoid abandonment and resubmittal for a permit. If that happens you'll be issued the new permit under the current code if it has changed, this can be a real problem. Talk to them and see how they handle it.

Adam Roby

The last time I spoke to the local inspector about building code and time-lines he was pretty vague with the details - and he seemed to be pretty relaxed on the details, but I will definitely speak to him again when I have a plan in hand... if not before. 

If it is OK to hang the girders from the posts (using the appropriate hardware), why is often said not to be OK to hang the floor joists from the girders using similar hardware?  Most posts I see tell people to have the floor joists sit on top of the girders rather than using floor hangers attached to them.


flyingvan

Find what you love and let it kill you.

Don_P

It is just about always better to stack wood on top of wood rather than using connectors to hang wood off of the side of wood. Sometimes, as in the case of the poorly braced pier posts, it is better to hang the girder off the side of a well braced tall post.

That said, joist hangers are fine for hanging joists most of the time. Where you can get into trouble is if there is a multi ply built up girder, which is generally the case. In that case the majority of the side load is carried by the first ply, significantly less by the next ply, significantly less than that by the third ply, and just about none by the 4th ply. With a built up girder and a side hung load nail them together very well. Ultimately a beam under a joist is more foolproof than a joist connected to the side of a beam by nails in shear. The connections in the first case are simply holding things together where in the second they are working.

The way you see most houses built on this site with a dropped girder (as opposed to a flush girder which is what you are asking about) I've commented and often wondered why people are doing it that way. The girder itself is laterally unrestrained, another unbraced hinge. In that situation dropping the joists into hangers on the side of the girder would help laterally restrain it, roll over protection.

flyingvan

    Completely agree that stacking lumber is always preferable.  I had to do this this way because AnnaMarie insisted on the wrap around porch,  and the wildland/urban unterface rules forbade more than 14" of exposed joist bay area , so stacking was out.  I had to 'T' all the beams in a herringbone pattern with a postcap at each junction; one of the beams didn't meet the 2/3 rule for cantilevers so had to pay for an engineers stamp there.  Roll over protection---I figured I'd prevent roll over by weighing down the rim joists with a house.   
     I was glad to be able to take off about a foot of elevation for the house by doing this.  The house was already taller than wide, I was bumping up against the height limit, and bridging to the porch would have been harder.
    The only thing these unstacked TJI's support is the floor itself.  Rim joists, beams, and squash blocks take the load
Find what you love and let it kill you.

Adam Roby

#17
I am reconsidering laminating 3 2x4's together rather than using 4x4's for the main posts.  If I did this, I would feel better about having sections removed to allow for the girders to be properly supported.  Then I could also add some 3x7 Simpson fastener/ties to keep it all together. 

Figure this would be a better solution?  One advantage I see is that I could laminate 8' pieces, which are much easier to transport than the 16' pieces I wanted for the center posts.


flyingvan

#18
If I were going to build like that (actually I have! lemme find some pictures)  I would turn the three 2x4's 90 degrees and run the crossbeam through the center, and continue it along the length of the structure.  Instead of going thick I'd go deep---like a 2x12 or14.  This works out neat because you can slip the crossbeam between the two outer 2x's, get it dead-nuts on level, then cut the peice that supports it.  You'd run carraige bolts through the whole mess, providing some diagonal support your current plan lacks
  That's my pavilion at home.  At the AirOps station I built a similar thing---- except it was supposed to last one year until we got our hangar, and had to withstand 400 MPH winds.  Having it blow apart in rotorwash into Lear Jets would be bad.  That was 7 years ago; still no hangar.

My front porch is built this way too.  I need a better close-up.



    All this said, I've only used this for building lightweight outdoor structures.    Someone esle with actual structural engineering background will have to tell you whether it's suitable for the increased deadloads associated with a habitable structure---but it's similar to pole construction so the numbers exist somewhere



Here's a little bit better picture.  YOu can see how the rail is sandwiched between the studs.  The rim joist below the decking is the same.  I just stuck it in and blocked it to match the ledger against the house

Find what you love and let it kill you.

Adam Roby

I am just in the process of redoing my drawings, and as I am documenting it I am finding ways to optimize the cuts, and use as much of the wood as possible.  I am looking for a good compromise between crawl space under the building and headroom inside the building.  As it stands, I have about 2 feet of room under the floor joists to move around down there, and about 7' 6" of headroom inside (between finished main floor and floor beams of loft area). 

1)  Should I try to make more room under the building, or is 2 feet enough.  I may one day want to add some plumbing (unlikely but possible), and I will probably want to insulate the floor from underneath at some point.  At the same time, I don't want to be too high off the ground.

2)  I think 7' 6" of headroom is more than ample, but would lowering that to 7' for example be very bad?  Any thoughts?


John Raabe

7'-6" is minimum head room for habitable spaces in most American building codes. Play houses and cottages seen in old British movies are often lower.
None of us are as smart as all of us.

Adam Roby

#21
In order for it to be even possible to build this alone in one summer, I decided to break it down into more manageable sections, and concentrate on each section one at a time.

This is the modified frame, using laminated 2x rather than 4x4 post.  The girders are now on top of members, and everything is bolted together.  I have hangers in place, but still need to add more supports and bracing.  I will update this again once I am sure on the details.

First the piers with cost breakdown.


Whole Frame (bracing still missing - more for proof of concept)


In order to make this more doable, the plan is to break down the build into different phases.  This phase is the basic structural phase, just the skeleton of the building with no sheathing.  Then, this phase is further broken down into 4 quadrants per floor.  The idea is that I can build just the front left lower quadrant and it will hold up by itself until another quadrant is attached to it.  Once all 4 are done on the main floor, I move up to the second floor, and finally the roof.

Lower front left quadrant example


Each section of each quadrant is then broken down into it's members, and a cost analysis is done which will be tallied up at the end.  Every section and beam is glued and screwed together.  Everything will be cut, end cuts treated, beams glued and screwed at home and just assembled on site.  This should make things go faster, since I can work on the sections during the week in my garage with electricity.  Once there I just bolt on or nail together whatever sections I made during the week.

Sample section with cost breakdown


If you think I am on the right track, I will continue like this until the entire cabin is sketched out and every last detail, nail and screw is accounted for.  Then I will have a realistic idea of how much this will end up costing, and how much time I will need to complete it.

A lot of this is just based on pricing at my local Home Depot.  I will likely look into how much it would be to get a trailer of concrete, rather than using 50 bags at 66 lbs each (talk about a lot of work).  Anyways, this will likely change a lot over the next year, but if I am to break ground next summer I think it is important to get this discussed and planned as much as possible ahead of time.  Thanks in advance for your comments... again, the bracing will be improved, and temporary pieced will be added to the drawings in due time.

John Raabe

How will you actually use this space? Where is the stair and the major fixtures and spaces - bathroom, kitchen, social area? How does it work with the site? I would suggest humanizing the building before getting too detailed with the structure.
None of us are as smart as all of us.

Don_P

quick thoughts, we need to run to Asheville and play with an experimental hazelnut sheller, woohoo :)

Flyingvan's approach is the way to go for building the columns, go to awc.org and read up on spaced columns in WSDD (wood structural design data), one of their free downloads.  The beams and columns could be built ahead of time and would look like mortise and tennoned timberframe components. The beam ends have very low bending moment and the tennon needs to resist the shear at that point, quite do-able with the single ply at the tennon IMO. I'd much prefer to see 2x6's, the column capacities need to be looked at but a 2x6 has alot more meat.

Lose the top plate dividing the upper gable and creating a hinge, those studs should run continuous fron 2nd floor to roof.

If the pier to post connection were plates embedded in the post and deeply into the pier you could get rid of most of that rotation point and make that connection rigid.

Adam Roby

#24
Quote from: John Raabe on April 18, 2014, 11:23:19 PM
How will you actually use this space? Where is the stair and the major fixtures and spaces - bathroom, kitchen,

social area? How does it work with the site? I would suggest humanizing the building before getting too detailed

with the structure.

I laid out how I thought I would put everything in the previous design, but I did not want to post the pictures because it shows the old connection points, and I also added to the height of the loft area since the space looks terrible small up there, head bumping territory.  I only had access to a few premade models, so I put in there some big beds, realistically I will likely have simply mattress or even blow up ones up there.  I also drew in a toilet (my skills are still in progress with this tool) but it will likely be just a chemical toilet.  I do see having a sink with some rain water collection to wash up, with a small grey water pit outside.  The structure will be used primarily by myself and my 4 year old daughter.  90% will be day trips, I don't see us staying up more than one night at a time. It will be 95% summer use, I may go up alone now and then more to check out the site and make sure things are secure.  The site is still in question as I have not yet purchased it.  I came very close to a beautiful site last year and lost it in a bidding war because I was stuck at work in Montreal and they needed me in person in Malone NY. 

(Please disregard the structural components in these, I am posting just for the layout reference)




Basically, I would have an 8'x8' section for bathroom/kitchen, an 8'x8' for a table, chairs, and door entry probably, 8'x8' for a sofa/lounge area, and 8'x8' for the ladder up, and possibly a small heating stove.

Quote from: Don_P on April 19, 2014, 05:41:18 AM
Flyingvan's approach is the way to go for building the columns...quite do-able with the single ply at the tennon IMO. I'd much prefer to see 2x6's...

Lose the top plate dividing the upper gable and creating a hinge, those studs should run continuous fron 2nd floor to roof.

If the pier to post connection were plates embedded in the post and deeply into the pier you could get rid of most of that rotation point and make that connection rigid.

Is this what you mean by the gable hinge?  My idea here was the properly brace the top of the side wall because it will extend higher than 2', probably in the neighborhood of 3 1/2 feet.  I was worried that it would want to separate, hence that peice in red.


Is my new design following Flyingvan's approach?  That was my intent, so if I did it wrong again please let me know. I have been tossing back and forth between the 2x4 and 2x6 laminated beams.  2x6 is most definitely stronger, but then my ties to the piers need to change, and all my exterior walls need to go to 2x6 rather than 2x4.  Since this will likely be used 95% of the time in the summer months, I did not think I really needed such a thick outter wall... but I am seriously rethinking this.

I am also not sure I understand the last part, the simpson carport saddles have rebar like bars that extend I think 12" down.  I have never done any rebar work, so I am a bit confused as to how it needs to be used, when the pier is mostly underground I would assume it doesn't need as much?  (Work in progress)

Thanks for the comments, these are extremely invaluable to me.  Hopefully I can have a complete plan in hand the day I buy the land.