Aluminium doors wind rating

I am currently in the process of getting a couple of quotes to replace an old Al sliding door. We live in a coastal town here in WA, the door faces towards the West, but has the deck roof as cover, so it is going to cop a fair bit of wind, but not much, if any rain.

The blokes I am getting quotes off are talking in terms of N rating, and a certain number of Pascals. Apparently standard doors are rated at N2, which is 700 Pascals, and N4 is 1800 Pascals. Two of the three quotes we got said that N4 would be recomended, but one of them went to commercial grade doors. When questioned, none of them could tell me what N rating the Commercial doors were, but they all asured me that they were significantly stronger. The first two guys are telling me that I COULD go to Commercial rating if I wanted to, but N4 would still be their choice, the last guy is sticking to his original opinion of Commercial only.

I am wondering if anyone could tell me how they decide what rating of doors they recomend, and how they come up with the rating? I did a quick Google, and came up with nothing. I looked up the B.O.M website to see an average wind rating, but again came up empty handed.

Is the difference between commercial doors and N4 that significant? I would have thought a commercial door would be designed to withstand a lot more traffic through it, rather than wind strength.

Anyway, if anyone could shed some light on this, I would be grateful!

Cheers

Jayson

hiya - ratings are for both frame and glass strength - for residential frame they usually weld a blade at 90 degrees to teh ddor on the mullions to give it strength for wind. For commercial frames, the frames are already 100 * 50mm aluminium versus 50mm by 30mm (or thereabouts) for res frame. Thus commercial framing might end up with neat box section instead of blades coming into the room for the door size. If the door is only 2100 high, then std capral commercial suite would be at least N3 and possibly N4 with 6.38 laminate glass

By and large, companies stick the rating in the computer, and the computer spits out the design and price. As size of opening and glass are relevant, there is no std easy answer, unless you call , "it depends" an answer?

Jayson,
The way it works up here is that on a new job, the plans and the engineer's cert. will state the terrain category of the building. Which the door manufacturer will then use to extract the wind loadings for his frames and glazing.
We must have a glazing certificate from a licensed manufacture to get a certificate of occupancy.

On a replacement job, if you are not changing any sizes, just swapping you can still replace same with same and claim it is maintenance and provided yet get a glazing cert. you will be OK.

In the lifetime of your old door, things have changed, it seems like every year upgrades to the codes come out. So what you will get now is a frame that is substantially thicker with deeper sections for greater strength and water penetration values etc. The old extrusions are not available any more.

There should be no way that if you are in an ordinary house should you have to use commercial sections. The only time I have done a job to a private house with commercial sliding doors is 100M from the sea and, get this, the doors were 2700 high.

I am in Darwin, cyclonic terrain category 2.5, just fitted two sliders, 2100 x 2100, powdercoat with security screens, out of standard Capral sections (that is standard for us, there could be lighter stuff that we don't see up here) and they cost $1,000 each, supply only.

As with any advice like this it can only be general, check your own conditions. Go and see the authority that will be signing it off. Get their information and recommendations.

Cheers
Bill

Cheers guys.

I was pretty certain that commercial doors was overkill, it's not like we are right on the ocean, in a cyclone zone or anything!

I have settled on the N4 rated sliding doors.

Thanks for the information.

Jayson.