Wednesday, September 12, 2007

Hang on to your hat

I could hardly believe it.

I was looking at a display for new roofing shingles at Lowe's. I was at the big box since the corner hardware stores are closed on Sunday. I wasn't shopping for shingles, but I was drawn by the pretty display which included large photographs of pretty houses showing off their new roofs.

And in the bullet-list of benefits was the shocking claim that these shingles were designed to withstand winds up to 60 miles per hour.

Sixty. Six-zero.

Who in the New Orleans area is buying these shingles?

Other shingles in the display promised protection up to 70 mph. What??

Doesn't everyone know that a Category 1 hurricane on the Saffir-Simpson Scale has winds from 74 to 95 mph?

And it gets worse. You’ll only get the promised protection if the shingles are installed properly. Although the instructions are clearly written on the label of every pack of shingles, don’t count on a contractor doing a proper installation job. I know of two people who read the instructions on the package and then watched the laborers proceed to do almost everything wrong. Both had to browbeat their contractor into following the proper installation procedures.

So for everyone who bought cheap shingles and had them installed improperly, how much wind can your house withstand? Hope you never have to find out.

Recall how many Blue Roofs you saw after Hurricane Katrina. FEMA reports they installed temporary tarps on nearly 100,000 houses under their "Blue Roof" program following Hurricane Katrina.

And aren't we fond of pointing out how minor the wind damage was in our fair city? Yet look at how many damaged roofs we had. (NOAA reported a maximum surface wind speed at New Orleans Lakefront Airport of 60 mph, with gusts up to 75 mph!)

I guess we know why now. Sixty miles per hour shingles? How crazy is that?

The current building code for the New Orleans area is 130 mph. That's according to the International Residence Code adopted by the State of Louisiana.

So if state law demands 130 mph, the question is not merely who is buying these substandard building materials. The question is also why is Lowe's or anyone else selling 60 and 70 mph shingles?

I suppose you could use them for other than residential construction. You might want to put them on your detached garage or garden shed. You might want to put them on a child's play house.

Sadly, that is not what is depicted in the pretty color photographs in the Lowe's display. They show these substandard shingles on the roofs of upscale homes. That is patently irresponsible and perhaps even dangerous.

We all want "Category 5 Levees"--I hear it on the radio and read it in the paper all the time. But Category 5 hurricanes also have winds of 155 mph or more. What good will tall and strong levees be if the houses just get blown apart by the wind?

How can anyone expect the rest of America to take us seriously when some of us are installing roof shingles that will not even survive a Category 1 hurricane?


mominem said...

Shingles are evaluated in accordance with UL 2390 and have a Class rating. Class is D (90 mph), G (120 mph), or H (150 mph) rating.

mominem said...

I also wanted to post that the specific wind speed a jurisdiction uses may be established by the jurisdiction. This allows for local governments to take practical considerations into account. You can check the actual wind speed requirement at the Louisiana Uniform Construction Code Council's web site

Tim said...

Thanks for that link. What it looks like they did was just interpolate off of this map:
This map shows Orleans Parish in a wind band from 120 to 130. To make it easier, the state folks probably just estimated the distance between 120 and 130 to get the numbers they show of 122, 123, etc.

Problem with that is the standard design manuals don't slice the bread that thin. The Wood Frame Construction Manual for high wind areas is published for 90, 100, 110, 120 and 130 mph. So you will end up desigining for 130 for single family wood frame homes anywhere in Orleans Parish.



ashley said...

Another question: what is Lowe's doing selling these things???

mominem said...

Yeah, I had a discussion with one of the members of the Louisiana Uniform Code Council yesterday informing her of my opinion that the tables were needlessly complex, overly precise and difficult to enforce.

Zip Codes are simply arbitrary areas established by the Post Office for mail delivery, what that has to do with wind speed it beyond me.