Bat House Forum

[Markcuda]

I am going to put two houses on one metal pipe.
Would 2.3/8ths out side diameter pipe be strong enough?
I can get schedule 40 or 80.
I will make my brackets to weld onto the pipe.
The houses will be back to back, 15 feet above ground.
One house is about 30ish pounds.

Edit=Here is a link to the house I have and will put up two more.
http://www.barninthesticks.com/looker-e ... bat-house/

Product Description
The Looker Products Extra Large bat house is big enough to host up to 600 mosquito eating bats. While some bat houses are just big enough to hold a small colony of male bats, this one is large enough to handle a breeding colony of bats. There is nylon mesh on the extended landing pad, and in the interior, to help bats move around better.

•Invite the best natural mosquito killer to your backyard!
•5 chambers- holds up to 600 little brown bats
•Built to the Organization for Bat Conservation specifications- over 10 years of research!
•Ventilation slot for proper air circulation
•Made in Illinios by Looker Products
•This bat house weighs 30 pounds! Be ready to get some help when putting it up!

$79.99, free shipping.

[William Bagwell]

We are going to have to just give up and kidnap us a mechanical engineer for this forum I'm not, but a 2 3/8" steel pipe 0.154 thousandths of an inch thick seems plenty strong enough to hold up a couple of 30 pound bat houses to me. Too lazy to look up the wall thickness of 2" (nominal) schedule 80, but it seems to me that if your worried about bending I would stick with schedule 40 and look at 2 1/2" nominal which is an 1/8" shy of 3" OD actual.

Oh, I just went looking for the dimensions of the Looker Extra Large and found it for $18 less on another site. No free shipping and I am very suspicious since they claim it only weights 10.89 pounds.

William

[Markcuda]

William, isn't the schedule 80 thicker than the 40?

[kent borcherding]

Put a smaller diameter pipe inside the larger outside pipe that you mount the bat house on.

The inside pipe does not have to be same length as the outside pipe-- inside pipe can be 5 ft. shorter than the outside pipe. Pipe will usually bend at the ground level , if not strong enough.

Also you will get less wind sway , bats sometimes will abandon a house due to excessive wind sway.

[Markcuda]

Put a smaller diameter pipe inside the larger outside pipe

That would work, but cost wise, it may be cheaper just getting the higher schedule 80 then?

A500 ERW Structural Carbon Steel Pipe - Uncoated 2 inch SCH 40 (2.375 OD X .154 wall) $79.59

A-500 Structural Steel Pipe - Uncoated 2 inch SCH 80 (2.375 OD X .218 wall)$134.82

[cloudman75]

Markcuda,
If you plan to install the bat houses back to back, then schedule 80, 2 inch would handle the job OK with 60 lbs as most of the force is straight down
until the wind blows. I had a bat house that weighed 75 lbs on 1 1/4 inch ID galvanized schedule 40 . The pipe was 21 ft long.It did just fine. If you are in a windy area with prevailing winds over 15 MPH, then the schedule 80 would be a better choice. The side force gets pretty large from the wind load with large heavy bat houses.The bracket will add to the weight, but schedule 80 will handle it OK in my opinion. I have added guy ropes when we had severe storms here
from high winds and have never lost a bat house yet. Schedule 80 is going to be heavy to lift, I can tell you that for sure. I would get the dimensions on the looker house before I bought it (them) if I were you. I did not see that in the add on the link. You might get by with schedule 40 pipe OK.

Edit: I found it on Amazon for 62 bucks plus 14 bucks shipping. It is 24x 21 1/2 x 7 , pretty big wind load so schedule 80 would do fine, while 40 might be pushing it depending on the wind in your area.

Frank

[Markcuda]

Frank, thank you very much for all the info.

[William Bagwell]

William, isn't the schedule 80 thicker than the 40?

Yes. Thicker, stronger, more resistant to bending and...

My point is that a one step increase in size from a 2 3/8" (2" nominal) to a 2 7/8" (2 1/2 nominal) will give an even *greater* increase in every thing that is important.

2" schedule 40 has a wall thickness of 0.154" and a weight per foot of 3.66 pounds.

2" schedule 80 has a wall thickness of 0.218" and a weight per foot of 5.08 pounds.

2 1/2" schedule 40 has a wall thickness of 0.203" and a weight per foot of 5.80 pounds.

Slight decrease in wall thickness verses the smaller thicker pipe, so you will loose a bit of corrosion resistance and longevity. Probably not a concern unless you live near the coast and salt air. Slight increase in weight which will add a bit to the price. If the prices are loosely tied to weight it should only be a small increase over the 2" schedule 80.

Yet as much of an increase in strength over the smaller 80 as the 80 is over the 40. Which is why we need an engineer who can explain section modulus

William

[cloudman75]

Just plug in the numbers to this formula William F= (Vg 2)(A)/ 390. Nothing to it. This gives the wind load a bat house presents to the pipe.
What you would need to get really technical is a structural engineer. We don't need to be that technical, just put up a great big old pipe and if that fails, put up a bigger one, or a little one inside the big un. LOL.


Frank

[William Bagwell]

F= (Vg 2)(A)/ 390. Nothing to it.

Without Googling the answer I'm guessing that,
F = Force
V = Velocity
g = grams???
A = Area
390 is the constant to divide by

So off to Google for the part(s) I'm not sure about...

[William Bagwell]

Hmm,
"No results found for "F= (Vg 2)(A)/ 390".
Results for F= (Vg 2)(A)/ 390 (without quotes):"

Going at it in reverse and searching for "calculating wind load" I find several sites offering "F = A x P x Cd" and variations as examples.
William

[Markcuda]

I think I just may go with the 2.1/2 inch pipe.
I think my metal guy said it was 9 bucks a foot

[cloudman75]

For you William: Your formula. Yours looks like a real one instead of the one I wrote just kidding.

P =.00256Vsquared . V = wind speed in MPH. IIll. speeds about 25 mph
F = force in pounds
A =area of bat house surface exposed to wind worst case broadside. 24 inches x 21 inches = 3.5 square ft.
Cd =drag coefficient for flat plate = 2.0

Then it stands that F=PxAxCd
.00256x 625x 3.5x 2.0 = 11.2 pounds

This is the horizontal force on the pipe due to the wind.
There is also the force due to bat houses with wind due to the length of the pipe as a fulcrum near the base of the pipe.
Schedule 80 pipe at 2 .5 inch dia would have plenty of strength to spare in my estimation.
A smaller pipe inside the larger as Kent said would make schedule 40 pipe serve just fine I would think. However the larger pipe all the way is probably just as cheap.

[cloudman75]

Way to go Markcuda. That size will give you some headroom with those cold gusty winds you may get up your way this winter.

Frank

[kent borcherding]

The $9 a foot price kind of bothers me.

there is a very large steel dealer 15 miles from my home .

He sells me 18 ft. heavy pipe for $18 - 2inch - the owners son enjoys nature and he knows use I use pipe for some of my bat houses.this is reason the price for pipe is reasonable.

Also I do not abuse the deal the company gives me- ie - such as buying pipe for friends that use pipe for different purposes than bat houses.

A plumber friend lets me pick thru his scrape pile for pipe that I put inside the 2 inch pipe. He gives me the pipe-free. Also I do not abuse this privilege , and give both people a nice Christmas present --cheese.

Possibly if you mention the pipe will be used to mount bat houses , they will give you a break on price , especially if you mention numbers of insects bats eat.