We are installing Simonton Prism Platinum Casement windows in our new AAC home, and supposedly they should be + or - DP=30 for Tallahassee. All the other windows except the casements say +50/-50 or so. Is it normal not to rate the casements for negative pressure, assuming the lach will hold greater than the glass? The Engineers sheet for attachment show +/- 50 or more.
Mike
Simonton Casement DP rating +50/0
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Mike Thomas
- Posts: 1
- Joined: Sat Oct 16, 2004 11:27 am
- Location: Tallahassee
DP Ratings
Mike,
It is normal to rate both positive and negative on windows. Why those particular windows show only a single rating is a bit of a puzzle. Did you happen to ask the company's rep why they only had the single rating?
I am also rather surprised that you only need a DP30 anywhere in Florida though - especially after this last year's hurricane season. Although, there are still a few issues to be worked out with the state-wide building code approval process, so that may be a bit of an issue and why you only need a 30.
You folks have had a serious taste of what adequate and inadequate building practices can accomplish; and if I were in Florida I would have the highest DP rating on my windows that the manufacturer offered!
DP65 is not at all uncommon, and I would hesitate to use anything less anywhere in Florida.
If we were discussing actual impact windows, I would tell you that the glass in the window was actually more impact resistant than your walls, unless you have poured concrete or concrete-filled block. I would also mention that the silicones used to glaze the glass into the sash have significant tensil strength and elasticity numbers. I mention this simply to emphasize that on an impact window the hardware (locks and hinges) are really the weak point of the unit. Yet on an "regular" window the hardware is probably not as good as it is on an impact window. "Probably", because it depends on the manufacturer as to what system they wish to use on their window.
Obviously, if the window in question is non-impact then the hardware system is not required to endure the same potential stress that "impact-hardware" is designed to accept.
Glass really is not as weak as people may think, and it can survive a pretty healthy dose of wind pressure; provided it is not forced to fend-off any other variables such as your neighbors lawn furniture or a failed lock system...
It is normal to rate both positive and negative on windows. Why those particular windows show only a single rating is a bit of a puzzle. Did you happen to ask the company's rep why they only had the single rating?
I am also rather surprised that you only need a DP30 anywhere in Florida though - especially after this last year's hurricane season. Although, there are still a few issues to be worked out with the state-wide building code approval process, so that may be a bit of an issue and why you only need a 30.
You folks have had a serious taste of what adequate and inadequate building practices can accomplish; and if I were in Florida I would have the highest DP rating on my windows that the manufacturer offered!
DP65 is not at all uncommon, and I would hesitate to use anything less anywhere in Florida.
If we were discussing actual impact windows, I would tell you that the glass in the window was actually more impact resistant than your walls, unless you have poured concrete or concrete-filled block. I would also mention that the silicones used to glaze the glass into the sash have significant tensil strength and elasticity numbers. I mention this simply to emphasize that on an impact window the hardware (locks and hinges) are really the weak point of the unit. Yet on an "regular" window the hardware is probably not as good as it is on an impact window. "Probably", because it depends on the manufacturer as to what system they wish to use on their window.
Obviously, if the window in question is non-impact then the hardware system is not required to endure the same potential stress that "impact-hardware" is designed to accept.
Glass really is not as weak as people may think, and it can survive a pretty healthy dose of wind pressure; provided it is not forced to fend-off any other variables such as your neighbors lawn furniture or a failed lock system...