[Steve Neul]

Hello, hope this post is in the appropriate forum...was wondering if anyone could give me some advice/opinions about setting a 4x6 pressure treated post in the ground: I plan to set in concrete an 8 foot, 4x6 pressure treated post 4 feet into the ground and then attach a 16 foot 4x4 post onto that which will have a 30 pound bat house attached to it. I was going to attach the 4x4 to the 4x6 with 2 inch galvanized lag bolts—4 of them spaced at 12 inches. I am hoping this 4x6 supports the 16 foot 4x4 being in the ground 4 feet although I have read that it should be much deeper. Ultimately, the bottom 4 feet of the 4x4 post with the attached bat house will be secured to the 4x6. Any thoughts are appreciated!

The suggested method of putting treated posts in the ground is to back fill the hole with gravel. I've never done that though. I've always put them into concrete. I build pole barns for shop space and use the 4x6 posts for that purpose. I had one building destroyed by a storm but the posts were fine. They were only in the ground 3' as at the time I built the building I was digging the holes by hand. Anyway I dug up the posts, broke the concrete off the wood and they were in great shape after 25 years. I went ahead and reused the posts to rebuild another building.

Treated wood is also suppose to be corrosive to metal parts but I've never had any problems with lag screws.

 

[35015]

The suggested method of putting treated posts in the ground is to back fill the hole with gravel. I've never done that though. I've always put them into concrete. I build pole barns for shop space and use the 4x6 posts for that purpose. I had one building destroyed by a storm but the posts were fine. They were only in the ground 3' as at the time I built the building I was digging the holes by hand. Anyway I dug up the posts, broke the concrete off the wood and they were in great shape after 25 years. I went ahead and reused the posts to rebuild another building.

Treated wood is also suppose to be corrosive to metal parts but I've never had any problems with lag screws.

I can not speak to your experience Steve that you have shared, nor do I know of what mitigating events could have contributed to the durability you suggested to have observed? It could be the soil type, biome specifics, aired climate, or other extenuating context, roof overhang coverage or the related details of the project...???...:|...or just not in the ground long enough?

What I can speak to on this matter, is hundreds of cases of decay I have personally observed, repaired and/or had to intervene on when the erroneous practice takes place. Wood embedded/encapsulated in OPC and related concrete materials...is a decay issue.

In some association and related building/architectural groups (and I've been told local code for some areas now) for "domestic architecture" embedment of...structural posts...in concrete for Pole Barns...Beach houses, and related "pole architecture," ...embedment of PT wood, Rot Resistant species, Telephone Poles, etc...is not allowed... because of the issues with wood rapidly decaying when encapsulated in concrete...Nor is structurally necessary or add any strength to a buildings "moment connection" strength or "uplift resistance"...

Whether "pile driven wood post" or "poteaux-en-terremodalities"...the majority is done (virtually all?)...without...concrete of any sort, and the only contemporary...decay issues...that have occurred with the historic vernacular systems of "post in ground" foundation systems occurred after the inappropriate embedment in concrete, and/or the improper wood species selection and application modalities...

Proper depth, back fill with gravel and/or stone, and a in soils with poor "load capacity" a footer stone...is al that is needed for a secure setting of such posts...

 

[Steve Neul]

I can not speak to your experience Steve that you have shared, nor do I know of what mitigating events could have contributed to the durability you suggested to have observed? It could be the soil type, biome specifics, aired climate, or other extenuating context, roof overhang coverage or the related details of the project...???...:|...or just not in the ground long enough?

What I can speak to on this matter, is hundreds of cases of decay I have personally observed, repaired and/or had to intervene on when the erroneous practice takes place. Wood embedded/encapsulated in OPC and related concrete materials...is a decay issue.

In some association and related building/architectural groups (and I've been told local code for some areas now) for "domestic architecture" embedment of...structural posts...in concrete for Pole Barns...Beach houses, and related "pole architecture," ...embedment of PT wood, Rot Resistant species, Telephone Poles, etc...is not allowed... because of the issues with wood rapidly decaying when encapsulated in concrete...Nor is structurally necessary or add any strength to a buildings "moment connection" strength or "uplift resistance"...

Whether "pile driven wood post" or "poteaux-en-terremodalities"...the majority is done (virtually all?)...without...concrete of any sort, and the only contemporary...decay issues...that have occurred with the historic vernacular systems of "post in ground" foundation systems occurred after the inappropriate embedment in concrete, and/or the improper wood species selection and application modalities...

Proper depth, back fill with gravel and/or stone, and a in soils with poor "load capacity" a footer stone...is al that is needed for a secure setting of such posts...

Where I live isn't that arid. The ground here pretty much stays wet from fall to late spring. The only problem I've ever had with pressure treated is when the wood wasn't properly treated. I've gotten a few round posts that about 1/2" of the exterior doesn't rot but the entire center rots away. Not just what is below grade but the entire post. I've heard stories about unscrupulous companies just hosing posts with the chemical to give it the green color instead of putting it in a tank and actually pressure treating it. I suspect these posts were some of those.

 

[Gus64]

Hello, hope this post is in the appropriate forum...was wondering if anyone could give me some advice/opinions about setting a 4x6 pressure treated post in the ground...Any thoughts are appreciated!

Hi Gus,

Looks like your already well into this project and have little to do than get it into the air?

I will assume you are just following standard "web base" plans for generic bat houses also.

I will add to others advise here...NO CONCRETE!!!..it will last longer and be more secure with just well packed rock and gravel around its base.

You can also extend the life span of the PT wood by charring the outside portion that goes into the ground and there are also "borate" and/or decay inhibitor "pills or plugs" that can get drilled into the wood at a later date should you wish or need more protection. PT wood is not as "rot resistant" in many of its forms as it is advertised by the manufacture.

If your design for the Bat House doesn't work as intended, don't hesitate to come back here for more assistance or drop me an email. I'm no longer an active member of BCI (Bat Conservation International) but once was in a professional capacity. Should you want to look at other examples of bat houses, check out "Chiroptera Architecture," for some ideas...I update it once or twice a year...<img src="http://www.woodworkingtalk.com/images/WoodworkingTalk_2016/smilies/tango_face_smile_big.png" border="0" alt="" title="Laugh" class="inlineimg" />

Good luck!

j

Yes, I built a 4 house chamber from the batcon site...was a fun, winter project I did with my stepson.

I do know it is suggested that you install a post in ground at least 1/3 to 1/2 of the length of the piece above ground and I am less than that recommendation. I think I would have to hire someone to dig an 6-8 foot hole so I am going to put the 4x6 in at 4-5' deep and hope for the best. I guess that's where I thought 8, 50 lb bags of concrete would give me a heavier base. Can always swap them for, say, modified stone? That packs quite well...

 

[GeorgeC]

Just curious, do you know that you have bats in your area?


George

 

[Gus64]

Just curious, do you know that you have bats in your area?


George

Yes, I have seen them in the summer months here in PA.

 

[holtzdreher]

I love having bats around, but another thing bats need is a nearby source of water. We had the most bats the summers we had an above ground pool for the kids. The bats would swoop down and skim just above the surface and dip their mouths into the water. We have a stream about 250 ft behind the house, and I have seen them skimming the water there too. I put up bat houses, but they have never been used. I have a few "den trees" not too far from the house, and I think they reside in those. One is a huge old poplar with lots of holes and hollows. I know I have seen owls and raccoons using the lower holes.

 

[Tool Agnostic]

I was taught to insert metal brackets in the concrete, then bolt the posts to the brackets. Around here, you don't want to put wood directly in concrete. Even treated wood won't last. You can find them at the big box hardware store. Go there to look at the assortment of different choices. Here is an example, but the ones we used recently are much heavier looking:

https://www.strongtie.com/standoffpostbases_castinplacepostbases/pbs_base/p/pbs

 

[Packard]

Sorry, the bolts are galvanized 2 inch diameter hex bolts--8 inch long...I will actually be using a 5/8 inch long one to use as the 'pivot' when raising the whole thing up...yes, we can't sit outside on our patio very long in the summer because the mosquitoes are so bad and are hoping to attract bats to help us out a bit!

I stayed at a bed and breakfast hotel in Connecticut a while back. They solved the mosquito problem by mounting ceiling fans on the full surround porch. They explained that with enough of a breeze the mosquitoes cannot light and bite. They mostly come out on the hottest days, so the fans are welcome.

It is more attractive and cheaper than a screened in porch. I sat out there for an hour or so after dinner and got not a signle bite.

A nice addition to the bat house strategy.

 

[GeorgeC]

I was taught to insert metal brackets in the concrete, then bolt the posts to the brackets. Around here, you don't want to put wood directly in concrete. Even treated wood won't last. You can find them at the big box hardware store. Go there to look at the assortment of different choices. Here is an example, but the ones we used recently are much heavier looking:

https://www.strongtie.com/standoffpostbases_castinplacepostbases/pbs_base/p/pbs

That would be a lot of work and very expensive for a fenced in yard. Never been done any place I have ever lived.


George

 

[Packard]

 

[GeorgeC]

Interesting. I would have to try some for holding power before installing a whole fence. Ii would not be interested in something like this bat house pole.



George

 

[Gus64]

Interesting. I would have to try some for holding power before installing a whole fence. Ii would not be interested in something like this bat house pole.




George

added 6" around the post at a time and tamped until it was filled then added a bit more around the base sloping away. Going to rain tonight and tomorrow so moisture seeping in should solidify it somewhat. The modified was a bit wet and packed well. We'll see how much the post holds. Rock-solid now but I wonder how it will hold the 4x4 and bat house attached. We shall see! Good info from everyone here and thank

 

[Gus64]

Interesting. I would have to try some for holding power before installing a whole fence. Ii would not be interested in something like this bat house pole.




George

added 6" around the post at a time and tamped until it was filled then added a bit more around the base sloping away. Going to rain tonight and tomorrow so moisture seeping in should solidify it somewhat. The modified was a bit wet and packed well. We'll see how much the post holds. Rock-solid now but I wonder how it will hold the 4x4 and bat house attached. We shall see! Good info from everyone here and thank

Sorry for the errors...used modified stone...thanks everyone for your thoughts and suggestions!

 

[Tool Agnostic]

That would be a lot of work and very expensive for a fenced in yard. Never been done any place I have ever lived. George

They don't do it with fences here. I never asked why, but cost seems like a reasonable explanation. They do it for mailboxes, patios, etc.

Photo: One of the posts that holds up the roof of our house. The white "square" underneath is also part of the same Simpson Strongtie metal bracket. It must have been painted white when it was originally set into the concrete foundation. That part of the roof extends over an open area outside to form a patio.

 

[Terry Q]

I think the 4x4 will eventually warp and bend over. A metal post would be better.


In woodworking there is always more then one way to accomplish something.

 

[35015]

They don't do it with fences here. I never asked why, but cost seems like a reasonable explanation. They do it for mailboxes, patios, etc. ....

That's called a "moment connection" in architectural engineering. I personally just don't care for the the way they look, and the ones needed for large and/or high post are indeed expensive. For fences, I have seen a number of projects where they where used, yet oddly enough the posts in those cases where metal...???...not wood.

I think the 4x4 will eventually warp and bend over. A metal post would be better...In woodworking there is always more then one way to accomplish something.

I have seen "Martin Boxes" (aka a type of bird) placed on metal flag poles...so there is precedent for such application for a metal pole. Rather expensive to get a good one tall enough for the applied application, and I have seen more than one of those fail too and bend over so not really an improvement over wood.

I don't disagree that wood can fail, but if due diligence is taken in selecting the correct species and/or piece of wood, they are more than durable...even in the 4x4 size range...

Case in point (of the countless posts in ground or related installations I have seen and/or worked on) the flag pole at a recent farm project is just one more example of..."knowing the what's and how's"...of tradtional woodworking, as this old Farmer did! This pole is Black Spruce off the farm and was installed in 1972...Its been in the weather since then and is still sound and functioning holding up "Old Glory." If wood is selected and treated properly...and allowed to "dry out"...which it can't do embedded in concrete...it will last a very, very long time! :laugh2:

 

[unburled]

My go-to for post setting is 1/4 minus, which is $2 per 5 gal bucket down the street

I dug up the posts, broke the concrete off the wood

I've recovered free-listed posts this way too, both metal and wood, just a few swings of an 8lb sledge then clean up if needed with a masonry wheeled angle grinder.

 

[Steve Neul]

My go-to for post setting is 1/4 minus, which is $2 per 5 gal bucket down the street



I've recovered free-listed posts this way too, both metal and wood, just a few swings of an 8lb sledge then clean up if needed with a masonry wheeled angle grinder.

I think if the wood is properly treated in a pressure tank there isn't anything you can do to it in normal construction to make it rot. Sometime before 1990 I made a retaining wall to make a road next to a pond which had about ten 4x6 posts set in concrete. The base of the posts are submerged in water for most of the year every year and the wall is still in great shape.

 

[unburled]

I think if the wood is properly treated in a pressure tank there isn't anything you can do to it in normal construction to make it rot. Sometime before 1990 I made a retaining wall to make a road next to a pond which had about ten 4x6 posts set in concrete. The base of the posts are submerged in water for most of the year every year and the wall is still in great shape.

I'll blabber a bit here. Those pre 1990 chemicals were probably different than today's, and there may not have been wetland/environmental based limits on your particular application. Generally speaking currently I see two types of PT in the stores. One is labeled ground-contact. The other non-ground-contact. But I use so much reclaimed wood that the question is whether it's been treated at all (has slits all over), then I get on with the project. Post longevity also depends on whether a cut end or factory end is put in the ground, and the actual chemicals used, which have changed over the years. Like I say, just blabbering on a bit. At times I've slathered on a 1/4" layer of roofing asphalt below grade.