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Thread: Hemlock posts vs Pressure treated

  1. #1

    Default Hemlock posts vs Pressure treated

    I'm building a playhouse - swingset for the kids & am considering 6x 6 hemlock for the posts & 4 x 6 for the beams.

    How would hemlock post embedded in concrete stand up vs a pressure treated post?

    In general, does hemlock stand up well or better to just go with PT?

    Thanks
    Graham

  2. #2
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    Default Re: Hemlock posts vs Pressure treated

    Hemlock is the same material that they used to build barns so id say it holds up very well .
    I would either wrap the wood at the end with plastic , poly or treat the end before pouring cement around it .

  3. #3
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    Default Re: Hemlock posts vs Pressure treated

    The mistake here is placing the timber, any timber into a concrete pocket. The post will rot completely off in under 5 years right at the interface between concrete, grade and the timber.

    Put concrete in the hole, place a post saddle in the top and place the wood on the saddle.

    Hemlock is not as strong as fir but is cheaper in most cases and looks just a nice.
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

  4. #4
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    Default Re: Hemlock posts vs Pressure treated

    I agree with Wyatt----but I used Hemlock years ago for a HUGE deck. Deep hole---(4')---coated everything in the ground with old oil and backfilled with sand and then water packed. Deck was built in '85---still standing.

    Today I would dig the hole---wrap the bottom of post in double large green garbage bags---seal top with silicone (above ground line) and back fill with stonedust and water pack. Worked great for my 15 year old fence.

    And Hemlock is cheaper and stronger thany any pressure treated
    "Born 50 years too late"

  5. #5
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    Default Re: Hemlock posts vs Pressure treated

    Mac,

    I've never thought of those ideas before. Cool. When I built my yellow cedar fence (6 foot high and about 700 LF) I used a post auger, set the rough sawn 4x4 and filled the remainder with 3/4" washed stone. Tamped it hard and built the panel - repeated many times. Should last me 20 years.
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

  6. #6
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    Default Re: Hemlock posts vs Pressure treated

    I agree with Wyatt. there is no reason to have the wood in direct contact with concrete, it will only come back to bite you in the ass. Use galv saddles and put some roofing membrane in between if you like. Do yourself and your kids a favour though and DO NOT use pressure treated. The sawdust is horrible for your lungs and kids being kids will touch the pt, then touch their eyes and mouth. It's bad stuff that will also hurt you down the road.

  7. #7
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    Default Re: Hemlock posts vs Pressure treated

    Most certainly, PT (the old green stuff) is nasty. The new brown stuff isn't as bad I don't think but any chemical that can rust through galvanized fasteners and clips can't be that good for you though.

    Personally, I use Cedar where possible. After that for a deck anyway I would use Mahogany (but that really depends on budget) and then and only then consider PT.
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

  8. #8
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    Default Re: Hemlock posts vs Pressure treated

    Someone please correct me if I am wrong, but if you cement the post in, bury the end of the post in gravel. The post is essentially standing in a bucket of water if the cement covers the bottom of the post. I wonder if the plastic might do just the same if it were buried with plastic wrapped over the end?
    you need pretty sturdy brackets to hold the post solid from the bottom if the post isn't buried. not that that is not possible, but they might add to the price?

    Kids might not want to play on it forever anyway so maybe it is better if it isn't built for forever? depends how much space you have I guess. of course it needs to be safe.


    Phil

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    Default Re: Hemlock posts vs Pressure treated

    Why not use a concrete base with a post anchor some of which are shown at this site.
    http://www.tamlyn.com/index_files/PostAnchors.htm


    You could have some fabricated by a local welder if so desired.

    Takes all the buried worries away and you can use untreated lumber.

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    Default Re: Hemlock posts vs Pressure treated

    Phil,

    You are correct. Concrete is a big spounge. It never completely cures and never really dries to 100%. Water is always a problem and concrete just makes it worse in this case.

    If you auger a sono-tube in the ground and then placed as you have indicated a simpson strong tie type product in the top and started at a corner you could get a lot of strength. Trouble here being that most of these are single direction fasteners where you need to be able to secure a fence post in 2 directions for it to really do what you want. Next, you need to consider wind loading on the fence and the type of connector you use. It is therefore beter to just dig the hole place the post in the ground with gravel around it.

    But there are many different schools of thought on this one so it really depends on if there is a bylaw or a code you are having to meet in your particular area more than anything.
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

  11. #11

    Default Re: Hemlock posts vs Pressure treated

    Quote Originally Posted by greid View Post
    I'm building a playhouse - swingset for the kids & am considering 6x 6 hemlock for the posts & 4 x 6 for the beams.

    How would hemlock post embedded in concrete stand up vs a pressure treated post?

    In general, does hemlock stand up well or better to just go with PT?

    Thanks
    Graham
    Graham

    I had to go back to the original post since there seems to be a lot of advice which would be OK for a deck or fence but when you are talking a playhouse and swingset I can see the possibility of posts being angled into the ground or at least having a lot of two directional stresses on them from the swings.
    I would also advise against wrapping the posts in plastic or setting them in concrete since both will promote rot. Just put your posts in the ground with gravel around them to provide drainage. If they are in 4 feet they are not going to move and will be there and strong longer than the kids are interested in either the playhouse or the swings.

    Blaine
    "Congratulations. You've just figured out the most complicated way to hold a board 30 inches off the floor."
    Tage Frid

  12. #12

    Default Re: Hemlock posts vs Pressure treated

    Thanks for all the responses.

    I hadn't thought of putting the posts in without concrete. I don't like the idea of using the brackets. The plan is 2 - 6 X 6 posts with a 4 x 8 or 10 beam on top to hold 2 swings. Without extra bracing I wouldn't trust brackets.

    Re the wood choice. I called a local mill & spoke with the owner who has run the mill for decades. He doesn't carry helmock & his view was that it would rot out in < 10 years & felt it would be too rough - too many splinters for kids. He suggested spurce or pine. I know an Amish mill that usually has helmock but you can't call.

    So, will plain spruce or pine stand up?

    Thanks again to all
    Graham

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    Default Re: Hemlock posts vs Pressure treated

    Unpainted or stained the spruce or pine will not last more than 5 years to be honest. Hemlock, in my opinion would last longer untreated because it is a stronger wood. It depends on the environment, the kind of temperature swings and the usage.

    On the subject of splinters - well, having a natural splinter from hemlock or anything else except cedar is much better for you then something coated with the PT (chromated copper arsenate (CCA), ammoniacal copper zinc arsenate (ACZA) and ammoniacal copper quat (ACQ)).

    Again, my opinion.
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

  14. #14
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    Default Re: Hemlock posts vs Pressure treated

    Without extra bracing I wouldn't trust brackets.
    With a proper designed bracket the failure point of the post in shear and bending would be the same as for one set in concrete.

  15. #15
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    Default Re: Hemlock posts vs Pressure treated

    Cross sectional shear and not vertical or axial shear...
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

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    Default Re: Hemlock posts vs Pressure treated

    I did the same thing when my kids were young, but nothing I built was permanent. Rather, I built a box using treated 4x6 large enough for a safe swinging area, then the inside of the box was filled with sand. Then, the vertical posts I bolted to the inside of the box, with some short braces bolted to the verticals and to the box. The swing set was rock solid, yet when the kids were too old for it, it was pretty easy to take apart. The playhouse was attached to the swing set, which also helped stabilize everything.

    But I would not build anything outside unless it was treated or cedar, anything else will rot after a few years.

    The toxicity of treated materials is also way over-blown. You don't need to take any extra precautions with PT wood, and if you're worried about splinters, run each side once through your planer first to smooth it out.

  17. #17
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    Default Re: Hemlock posts vs Pressure treated

    I disagree about PT. Why would Simpson release an entire set of "special hangers and fasteners to counteract against the failures associated with the PT eating through standard galvanized materials? If it does that, it will do many other things...

    I still use it but not to the level that some do.
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

  18. #18
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    Default Re: Hemlock posts vs Pressure treated

    At the same time, if it were unsafe for human use, it wouldn't be on the market. Different materials react differently to different things. Just look at hos some liquids will eat through plastic, but not touch glass, or vice versa. Just because the current gen of PT causes damage to standard exterior grade metals and fasteners, doesn't necessarily mean it is unsafe for human use (of course, you don't want to eat the wood...)

  19. #19
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    Default Re: Hemlock posts vs Pressure treated

    Again, being on the market isn't as safe as you might think. Think of those plastic bottles we all used for years only to find out that they are harmful.

    CSA does a great job but sometimes there just isn't enough time or money to complete a long term testing.

    This is my opinion but I would not use PT for veggie gardens, play grounds or sun decks where kids would be playing on, over or through them. I don't have kids so using PT for a deck for me isn't a huge deal.

    All I'm saying is one needs to make educated choices is all. If you deem the cost difference acceptable to your risk tolerance then by all means go for it.

    On the subject of eating the wood - if you are like me and have dogs the cuttings from the chop saw almost always end up as some sort of "toy" and get chewed on. So the chemicals are getting eaten, just not by a human. Again, a risk I don't want but one that others can take.

    To each his own.
    Wyatt Earp
    My wife's Mr. Fix It. Construction Manager by day, hobbist when I find time.

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