Prolly a 6' fence because there are 3 stringers (the horizontal boards). A 4' fence could get by with just 2 stringers.

It is perhaps 8 feet. Certainly not 4 feet. Could you offer further explanation?

The reason i ask is because when i was searching for images of the "jack pear tree" this photo came up. The tree is supposed to be a dwarf version of the bradford flowering pear and top out at around 15 feet high by 10 feet wide. Even the bradfords dont have trunks that you can walk under. This is why i am thinking the fence is 4 feet.

Definitely not 4 feet high.

6 feet. I've installed several like that.

Those red pavers on the ground are probably 12 inches in diameter, for another reference.

I'm putting it at 5 feet. The stringers are 2x4's and the posts are 4x4's, both of which have an actual face dimension of 3.5". Laying a ruler on the photo, it looks like the height of the fence boards is about 17 times the height of one of the stringers. So 17 times 3.5" is close to 60"...5 feet.

This post was edited by kudzu9 on Fri, Nov 21, 14 at 6:52

Standard 6' fencing materials.

Standard 6' fencing material..... just like hollysprings says.

If those are standard fencing materials, then those are 2x4 stringers. The fence boards may have been standard six footers, but that doesn't mean they weren't shortened for the installation. If someone else gets a different math result than I did by doing a ratio that compares the standard width of a 2x4 (3-1/2") to the height of the fence boards, and comes up with the height being 6', I'll be happy to change my mind. For now I'm sticking with a fence close to 5' high.

The tree is supposed to be a dwarf version of the bradford flowering pear and top out at around 15 feet high by 10 feet wide.

The "mature size" on a tag is the average 10-year size for that variety. Divide the mature size by 10, and you have the average growth per year.

After reaching 10 years of age, woody plants just continue growing at that rate. Some might grow a bit more slowly than when they were young, but they definitely keep growing.

Dwarf trees and shrubs simply grow less per year than their full-size kin.

Even the bradfords dont have trunks that you can walk under.

Well, generally you don't walk under the trunk of a tree. Under its branches, yes. Bradford pears can certainly be walked under if the branches are pruned to 6 or 7 feet. There are several dozen Bradfords -- which can be walked under -- in four yards across the street from me, and in the golf course just down the street.

Unfortunately too many of their seedlings end up in my yard, which they are attempting to take over, but that's another issue -- though one you might keep in mind before you decide to plant one. Oh, and the younger generation usually bears vicious thorns.

Could be 4ft or 6ft, they make prefab sections in both heights. I scaled off the pickets; if they are 6" wide, it is a 6ft high panel, if it's a 4" picket, 4ft tall.
I'm assuming the post spacing is 8ft, which is about the maximum to maintain any wind-resistance to the structure, which would fit proportionally with a 6ft ht.
Casey

Here is a link that might be useful: prefab 6ft fence panel

sombreuil_mongrel-
In my neck of the woods, I've seen so-called 4" fenceboards that measured anywhere from 3-3/8" to a little over 4" wide, depending on who was selling them; the same with ones that are nominally 6" wide. That's enough of a difference to make scaling from them unreliable. I think it's safer to assume that the stringers are 3-1/2" wide 2x4's, and use that dimension to scale up. When I looked at the 6' high fence section in your link, I saw proportionately more space between the stringers than in the OP's photo. When I scale up from the 2x4 stringers in your link, I get a 6' high fence. When I do the same with the OP's photo, I get about a 5' high fence.

Pre-mades don't use 2x4. They use maybe 1x3 crap. (Been a while since I went down that aisle at the Despot.) Which is why you see so many broken.

It's 6'.

oh beany ... you are a Bradford pear idiot savant ...lol

how many forums have you posted about this invasive PIA tree ...

under how many GW names ...

again.. that is not a dwarf... i can tell by the height versus the trunk diameter ...

as far as i am concerned.. its all marketing hype... you cant find it.. because.. most likely.. it doesnt exist ... outside the ether of the www .....

just buy one ... and plant it ... and quit posting about them ..

you know the topic sets us all off.. and that is why you are now posting bradford pear questions in the home repair forum ...

but if you do.. just dont tell us.. brag to us.. that you did so ... we will not be impressed ...

ken

ps: i have one.. because my inlaws thought it would be a wonderful house warming gift ... what can i do ... kill it??? .... but it smells horrid in flower.. and i see the squirrels are eating the fruit.. which means now that its mature enough.. that i will probably be killing them by the hundreds.. in the years to come ...

hollysprings-
But the fence in the OP's photo doesn't look pre-made, so I don't understand how you can so confidently assert it's 6' high.

If the horizontals are 2x4's then the fence is 60" tall. Just scale off the 2x4.
Casey

I tried scaling and from the looks of it, that fence is definitely not a 4 feeter. It could be 6 maybe 8 feet tops.

For those having difficulty with the concept of estimating the height of this fence by scaling, take a look at the photo below:

The fence is about 274 units high and the 2x4 stretchers are about 16 units wide. Dividing 274 by 16 = 17.1. Using a standard width of 3.5" for the 2x4, fence height = 17.1 X 3.5" = 60". Now the photo is fuzzy enough that the height computed might be plus or minus an inch or two, but there is no way it is 6' high or more.

Thanks kudzu9 for taking the time to do that.

tlbean-
You're welcome. When I first posted, I thought the method I used was pretty straightforward, and that would be the end of it. After others seemed to ignore this mathematical approach in favor of their own assumptions, I thought maybe if I explained it again using a picture I'd be able to make some headway.

So, what size do you think this panel is?

hollysprings-
The proportions match a fence section that is 6' tall and 8' wide. Unlike the original photo in this thread, there are no fence posts to give it scale, and it's a head-on shot rather than something more oblique (which would provide more clues), but those don't look like 2x4 stringers; they look like something undersize...maybe something about 3" wide, based on the scaling proportions.

Are you trying to figure out what the proportions are, or is this a test?

This post was edited by kudzu9 on Wed, Nov 26, 14 at 1:35

Engineering: an Exact science,........ based upon ASSUMPTIONS.

snoonby-
In this case, given what there is to work with, you're right that using assumptions is unavoidable. But some assumptions may be less speculative than others. However, I don't know any engineers who think, in general, that it's an exact science, although we sometimes can conclude that some results are more precise than others.

So, how many different conclusions can be wrought, using the same set of mathematical assumptions?

How many angels can dance on the head of a pin?

I thought, at least in our field, assumptions are only for estimates, we don't use assumptions for EXACT calculations in Science and Engineering.

azmom-
It's a question of terminology. Calculations are exact -- if we accept how math works -- but there are all kinds of assumptions that come into play in the real world of applied engineering. Even something as simple as calculating the circumference of a round object has assumptions. First, do we assume it's perfectly round? Second, how precisely has the diameter been measured?: One decimal place?, Three? Ten? And, third, what do we assume for the value of pi?: 3.14? 3.14159? 3.14159265358979323846264338327950288419716939937510?

More to the point, if I wanted to calculate the resistance of that fence to severe wind loading, I would need to know (or assume) the wood species of the fence posts, I would need to know (or assume or estimate) their actual cross-sectional dimensions, I would need to know (or assume or estimate) the actual fence height, and I would need to make some assumptions about how to deal with the issue of gaps between fence board edges. Even if I didn't know all of these things precisely, I could make a fairly accurate engineering calculation of wind resistance, but it would get somewhat better if I knew everything precisely. And in any case, I would need to assume a value for the strength of the wood posts based on average data for that type of wood, when, in fact, each of those posts might have slightly different characteristics. So, no matter how precise I felt my numbers and calculations were, there would still be some imprecision.

In general, I'd say that engineering calculations are almost never exact, but they can be extremely accurate...accurate enough to make no practical difference. There's a reason people use the phrase: "Good enough for engineering work." It means that you get to a point where you've got a sufficient answer and further precision won't necessarily improve the conclusion.

I did a calculation of the fence height using assumptions and a method that I explained, and came to a conclusion that it was about 5' high, give or take an inch or two. The method I used was the one I thought the best available based on what I had to work with. I satisfied myself that the fence was not 4' tall and that it wasn't 6' tall or 8' tall, but pretty close to 5' feet tall. If it is actually 5'-1-3/4" tall, will that make a difference to the OP?

kudzu9

You omitted soil compaction as well as emersion as a function of the resistance, however, since wind loading has little value in computing resistance to overturning moment, below 6', only the panels would be affected.

azmom

Regarding the building trades, there are an established set of assumption, for from subterranean to the height of the tallest structure, which when employed correctly, demand an exact conclusion and were these assumptions left to chance, there would not be a building permit issued, let alone standing.

Scientific and engineering conclusion arrived at, as the result of a consensus, indicates that not a person among that group is willing to assume responsibility for the conclusion, automatically drawing into question, their methodology.

snoonyb-
I know. There were so many things I left out...I plead incompetence. My only excuse was I thought I was already too windy to make the post any longer. Nonetheless, I thought it was good enough for engineering work! :)

Kudzu9 and Snoonyb-

You do use different terminologies.

We use definitions, requirements so that there will be no ambiguity. We want concrete, exact, leave no room for interpretations. For example use 258-bit to represent data precision, or khz as refreshing rate...

This is fun! Learn something new every day!