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| Author: | Shelley Boyd |
| Subject: | Tornado damage |
| Posted At: | 2004-08-15 02:32:47 |
I am NEW at all of this!
Anyway, earlier this Spring, our home was damaged when 2 tornados went through our neighborhood. Our 6x8 foot master bedroom window will need to be replaced. It has the half circle on top of 2 double hungs. My question is this; Which window is the best to get to replace our damaged one. Keeping in mind that we live on the second highest hill in the county. It is not unusual for us to get 60 mph or more winds here. A "Capital" window was what came with the house and we have not been happy with it. Insurance will be paying for it, although I don't know yet how much we will be aloted. They have been really good with us, so far. Any insight or advise is welcome and appreciated.
Thanks
| Author: | Jeff W |
| In Reply To: | Tornado damage (posted by Shelley Boyd) |
| Subject: | RE: Tornado damage |
| Posted At: | 2004-08-15 14:45:31 |
DP rating(Design Pressure) should be a main factor in determining the window you choose. Many lower cost windows have a DP rating of R25 which your Capital probably did. In these winds you have they will leak air. The better the DP rating the more wind they can handle without leaking air. A DP of 60 is about the best for a window unit. I would not consider anything less than a DP 45 in your situation. I am not as pronounced in the technical aspects as some of the others here and they may be able to give you further input. It costs a mfg about $20,000 to have a window tested so many companies do not have this info available. Several here will suggest Schuco. We have used the Milgard Classic(not styleline) and are pleased with them. Traditionally double hung windows leak air more than casements(3-5x as much) in that as the wind blows the casements are forced tighter to the weather stripping to reduce air. If any window is installed out of square you will get more air leakage. Some mfg will give you air infiltration ratings that you can use to help decide. Hope this helps and good luck.
| Author: | Oberon |
| In Reply To: | Tornado damage (posted by Shelley Boyd) |
| Subject: | RE: Tornado damage |
| Posted At: | 2004-08-15 18:39:50 |
Hi Shelley, welcome to Tim's window world!
Jeff, great answer. I am going to add a bit of background for our "non-technical" folks.
I will TRY to keep it short!
Shelley, did your windows break from actual wind pressure? Or were they impacted by junk being tossed around by the tornado?
As Jeff mentioned, testing and certification of building products is extremely expensive. Many companies simply cannot afford the "luxury" of having their windows tested and certified.
Jeff also mentioned that your windows may have been rated for a DP (Design Pressure) of only 25.
That "25" is based on a Per Square Foot (PSF) measurement of the window systems windload performance. So if you have windows rated at DP25, then that means that they are certified to be able to withstand that pressure...
But, it isn't quite that simple.
When a window is rated at DP25, it has actually withstood a pressure "force" of 1.5 times that 25psf. So, a window rated at DP25 has actually withstood a pressure of 37.5psf (25 x 1.5)during the testing.
Is that confusing enough?
Now, the big question. What does that 25psf equivalent to measured in actual windspeed?
An DP25 equals a windspeed of 100mph...but, when taken to 37.5psf, we jump up to about 120mph wind.
Jeff suggested at least a DP45 (a very good suggestion, in my opinion, btw), which would equal a windspeed of 135mph at 45psf.
But, again, the window is tested at 1.5 times the DP rating, so we are testing at 67.5psf, or windspeed of 164mph.
Making sense so far?
You might have noticed that DP25 at 100mph and DP45 at 135mph does not appear to be a linear increase; and while 45 is almost double 25, 135 is certainly not almost double 100...Thinking here how best to attempt to explain...and not coming up with a very good way to do it.
Here goes anyway.
Imagine that virtually ANY window is strong enough to stop some wind, so that said window has a "head start" over the wind pressure when comparing figures.
Imagine that a window is strong enough to sustain 10psf (which isn't much at all) and 10psf equals 63mph windspeed.
From that you can see that, initially, the window (pressure) has a built-in "head start" advantage over windspeed in performance comparison. It takes a lot of wind - initially - to affect even a low pressure-rated window.
The initial advantage of the "head start" gradually narrows as the pressure increases...in other words, as the pressure rating increases, the comparison to the actual windspeed becomes closer and closer until a pressure of 400psf will equal 400mph windspeed...figures we really don't care much about on this forum!
And so, although the DP of the windows used in the comparisons almost doubled, the actual wind-speed window performance increased by substantially less.
This is far from an ideal explanation (it can be difficult to try to explain something in words when math - including a bit of graphing - is really needed to actually explain), but I hope it makes some sense.
And now after all that, the question still to be answered is whether the windows broke from pressure or debris impact.
Studies have shown that in major storms, a significant (huge) majority of window breakage is caused by impacts and not by windpressure alone. Thus the "hurricane" codes popping up all over the coastal areas of the US.
Shelley, if impacts are a potential problem in your environment, then you might actually want to consider impact rated windows...
And since this is already pretty long, I will go into the impact requirements and relation to windzones and pressures and storms and "stuff", only if you think it might be of value to you or if anyone else really wants to read it!
Hasta La Vista!
| Author: | Shelley |
| In Reply To: | RE: Tornado damage (posted by Oberon) |
| Subject: | RE: Tornado damage |
| Posted At: | 2004-08-15 19:27:37 |
Thank you for the nice welcome! I am so glad to join in!
Yes, all of our Capital windows leak air. Some more than others. One window lost its seal the first year that we lived here. Capital would not help us with the window problems. Since our builder filed bankruptcy before he finished our home, we have had much to contend with, including no paper work on the windows.
Our window actually did not break during the tornados. It does look like it lost its seal, though. I would guess that it was from the wind pressure. They said that tornados were at least 150 mph. Many folks here are just having to bulldoze what is left of their homes and start over.
I don't think that impacts are really are problem, here. This was just a large cornfield before the houses were built. We used to have a wind guage outside, but it only went up to 60mph. I have seen it "pegged out" many times!
Thank your for putting your info into non-tech terms!
I have thought about the Schuco windows, since they are so well thought of on this forum. Really don't know if a dealer is in this area. I live in Southern Indiana, about 30 miles north of Louisville Kentucky.
My Pastor has offered to get us a Siminton window for what his cost is. He does remodeling on the side.
Any comments?
Thank you!
| Author: | Installation Masters Inc. |
| In Reply To: | RE: Tornado damage (posted by Shelley) |
| Subject: | Capitol |
| Posted At: | 2004-08-16 13:47:16 |
Shelley, check with your insurance company and see if they have you covered with "replacement or equal" for damaged goods. You'll be better off knowing that. You can then shop around. If not they make you use another Capitol product. I was never a Capitol fan when we installed them here in town for a national contractor. The local job supervisor thought they were junk also. He wanted them out and thought he could test the home for air leakage and they would fail. Wrong idea I guess. The windows had a 98% passing score in three different houses. I was impressed!! I don't know how much of the test was from proper installation or product though. FenX might see that more. I know Capitol has a great Sound and Impact window. We installed tons of them over the past two years. They weigh a ton and perform well. I just wish they would use a better vinyl. Very flimsy and cheap. Any ways just thought I'd chime in my two cents. Good Luck!!