wind loading on windows.

wazzoraybelle

I am concerned about windows we have ordered. The certificate of performance states a wind load class of C3. We live on an extremely exposed cliff top. The engineers are not responding to my e-mails but earlier claimed that they conducted a wind load calculation and that this was passed on to the supplier. The supplier has told me that he received no wind load calculation.

Could someone please explain what wind load Class C3 means? And if such a class is suitable for exposed coastal dwellings? Or provide a link that explains these wind classes?

Much appreciated.

Wazzo

BryanF

So how come there are ordered ?

Your engineer hasn't signed off of the suppliers wind load calcs?

BryanF

http://www.boards.ie/vbulletin/showthread.php?p=88872810

Are you still building?

wazzoraybelle

BryanF wrote: »

So how come there are ordered ?

Your engineer hasn't signed off of the suppliers wind load calcs?

We paid our deposit on the windows, after being requested to do so by our architect, I brought up the lack of any wind load calculation and the architect said one would be requested of the engineer. We never saw this calculation and the windows were ordered by the supplier.

There's a lot more to the story, but I'd feather not get into it here.

Wazzo

Metric Tensor

I might be corrected but I think C3 is an exposure class for steel to do with how corrosive the environment is -

http://www.steelconstruction.info/Standard_corrosion_protection_systems_for_buildings

Wind loading should be calculated in accordance with IS EN 1991 for the specific part of the country in which you are located.

wazzoraybelle

BryanF wrote: »

http://www.boards.ie/vbulletin/showthread.php?p=88872810

Are you still building?

Unfortunately, we are. We are in the process of trying to restart work. We are concerned now that the windows ( v. expensive) will not withstand the winter gales.

wazzoraybelle

Metric Tensor wrote: »

I might be corrected but I think C3 is an exposure class for steel to do with how corrosive the environment is -

http://www.steelconstruction.info/Standard_corrosion_protection_systems_for_buildings

Wind loading should be calculated in accordance with IS EN 1991 for the specific part of the country in which you are located.

The Certificate of performance from the window manufacturer states the wind load class to be C3. I just don't know what that means.

wazzoraybelle

The windows are timber sash if that helps.

Metric Tensor

It could be a classification in a window code so - I'm sorry it's not one I know any more about.

sydthebeat

wind loads are generally described as the pascals they are tested to ie 2400 in accordance with en 12210

can i assume they have been described as class 3 1200pa ?

it appears 1200 pascals of pressure equates to winds of approx 160 km/hr
http://www.climatec-windows.co.uk/pdf/specifiers/Windspeed%20to%20Pressure%20Conversion%20Table.pdf

Calahonda52

Interesting topic, which piqued my interest.
Came across the attached, dated 2014, from a latvian manufacturer.

Its all in english and might help the OP and MT
It certainly helped me.

The second last page is worth a look.

OP, in passing, given your location, whats the expected A/T value?
Thanks

Metric Tensor

Learn something new every day! - Thanks CH and syd.

Metric Tensor

So class C3 is a deflection of less than 1 in 300 at a pressure of 1200 pascals.

Then OP your engineer needs to address the wind load for your location (using IS EN 1991) to see if it is less or more than 1200 pascals.

Metric Tensor

sydthebeat wrote: »

it appears 1200 pascals of pressure equates to winds of approx 160 km/hr

1200 Pascals would be towards the high end but a not unheard of number for wind pressure in Ireland.

wazzoraybelle

Many thanks Calahonda52 and metric tensor.

I'm don't know what is meant by A/T.

We are on a located on a 40m above sea level cliff top on the south coast. In February 2014 gusts of 178kmph were recorded at the Kinsale gas field which are 25 nautical miles directly south of us (with only ocean in between).



We have a steep orography also with the land falling to the ocean at about 1 metre per metre, ( I've heard that slopes can accelerate wind speed)

BryanF

wazzoraybelle wrote: »

I'm don't know what is meant by A/T.

)

Air-tightness

wazzoraybelle wrote: »

We paid our deposit on the windows, after being requested to do so by our architect, I brought up the lack of any wind load calculation and the architect said one would be requested of the engineer. We never saw this calculation and the windows were ordered by the supplier.

There's a lot more to the story, but I'd feather not get into it here.

Wazzo

Assuming you haven't paid in-full for the Windows, and your eng/arch Are not supporting the build, perhaps you could
Contact the supplier and ask them to do their own assessment and provide a wind calculation or declaration of Preformance that they are complying with the en standards as listed above (associated with your specific costal location). Tell them your assigned certifer won't certifer the glazing/ building without this declaration, hence you can't realise their funds, unless they produce the relevant cert etc

Metric Tensor

BryanF wrote: »

Contact the supplier and ask them to do their own assessment and provide a wind calculation or declaration of Preformance that they are complying with the en standards as listed above (associated with your specific costal location). Tell them your assigned certifer won't certifer the glazing/ building without this declaration, hence you can't realise their funds, unless they produce the relevant cert etc

Excellent idea - they should be doing this anyway!

How about the fixing of the windows to the walls OP - they might be more likely to give trouble in high winds (and vibrations) than the unit itself.

wazzoraybelle

Thanks, I don't know if the window supplier would have any liability in a situation where there was an architect and engineer involved.

The window supplier has also been very accommodating in storing these windows at no charge for 2 years now.

I found a map on the met eireann website that shows our location to be in an area that experiences winds in excess of 47-48m/s once every 50 years.

That would seem to equate to 1300-1500 Pa.

Looking at the COP it appears the reference window for the test is about half the size of the windows we have ordered.

Thanks for all the advice, much appreciated.

Wazzo

Calahonda52

Well, gusts of 175km/hr will get you attention!

Apart from the windows, I trust the rest of the design reflects this exposed position:
The roof in particular.

Whats the makeup of the external wall finish

My only experience of this sort of 1 in X years was in the '70's I worked as a site engineer on a new 2km harbour breakwater, built primarily with concrete armour.

The design was to resist a 1 in 100 year storm.

It was a big project, with an Government attended official opening on a weekend in June.

A wee storm arrived on the Wednesday, when it had cleared, there was nothing visible left of the breakwater.
The storm was a 1 in 150 year....

wazzoraybelle

Calahonda52 wrote: »

Well, gusts of 175km/hr will get you attention!

Apart from the windows, I trust the rest of the design reflects this exposed position:
The roof in particular.

Whats the makeup of the external wall finish

My only experience of this sort of 1 in X years was in the '70's I worked as a site engineer on a new 2km harbour breakwater, built primarily with concrete armour.

The design was to resist a 1 in 100 year storm.

It was a big project, with an Government attended official opening on a weekend in June.

A wee storm arrived on the Wednesday, when it had cleared, there was nothing visible left of the breakwater.
The storm was a 1 in 150 year....

The rest of the project was a complete disaster, I was hoping that the windows may have been salvageable.

The building itself is 150 years old, with the external masonry leaf comprising of 400mm lime rubble wall with a 60mm concrete render.

Metric Tensor

As CH pointed out the roof is one of the big concerns in this type of environment.

BryanF

wazzoraybelle wrote: »

Thanks, I don't know if the window supplier would have any liability in a situation where there was an architect and engineer involved.

The window supplier has also been very accommodating in storing these windows at no charge for 2 years now.

I found a map on the met eireann website that shows our location to be in an area that experiences winds in excess of 47-48m/s once every 50 years.

That would seem to equate to 1300-1500 Pa.

Looking at the COP it appears the reference window for the test is about half the size of the windows we have ordered.

Thanks for all the advice, much appreciated.

Wazzo

There are too many 'seems' 'appears' & varying winds contradictions IMO.

Why are you letting the 'specialist supplier who has design liability of the hook?

wazzoraybelle

BryanF wrote: »

There are too many 'seems' 'appears' & varying winds contradictions IMO.

Why are you letting the 'specialist supplier who has design liability of the hook?

Really I'm not letting anyone off the hook, whatever 'seems' and 'appears' there are are based on my own lack of knowledge. I was looking up the eurocode and it just reads like double dutch to me. I am however a keen weather watcher and have a clear understanding of wind forces.

If there is accountability due from the window supplier I will certainly be following up on it

80% of the window cost has been paid, and the architects were sent the window schedule, prior to ordering, with the certificates of performance several weeks before the project fell apart.

The reason for my initial post was merely to try and get an understanding of what the wind load class on the certificate meant.

Metric Tensor

wazzoraybelle wrote: »

I was looking up the eurocode and it just reads like double dutch to me. I am however a keen weather watcher and have a clear understanding of wind forces.

The Eurocodes in general are difficult to read and the wind loading one is particularly challenging. You really need an engineer to do it for you.

As BryanF said the window manufacturers should be doing it in order to prove that the windows they are selling you are fit for purpose. However, I haven't seen any window company do this to date so you may have to get an engineer involved by some other means.

Although wind loading is primarily related to wind speed it depends on the shape, orientation and height of your house too. It also can cause negative pressures when blowing from different directions.

wazzoraybelle

Metric Tensor wrote: »

The Eurocodes in general are difficult to read and the wind loading one is particularly challenging. You really need an engineer to do it for you.

As BryanF said the window manufacturers should be doing it in order to prove that the windows they are selling you are fit for purpose. However, I haven't seen any window company do this to date so you may have to get an engineer involved by some other means.

Although wind loading is primarily related to wind speed it depends on the shape, orientation and height of your house too. It also can cause negative pressures when blowing from different directions.

Yup, definitely not straight forward.

We have had several engineers walking in and out of our home over the last 2 years (and paid handsomely for their time), but they were concerned with other (very serious) aspects of the building works. We have boxes of reports and files. I'd hoped that at least the windows were kosher.

Metric Tensor

Ah. I see. No-one wants to take over someone else's half completed problems?

Not a whole lot more to say really - thanks to CH you know what class c3 means in terms of loading and in my opinion, for your location, you need to investigate if the loadings might be too high for these windows. It might be OK but it might not.

OR - alternatively - have the window company confirm in writing that the windows are structurally sufficient for your specific house

wazzoraybelle

Metric Tensor wrote: »

Ah. I see. No-one wants to take over someone else's half completed problems?

Not a whole lot more to say really - thanks to CH you know what class c3 means in terms of loading and in my opinion, for your location, you need to investigate if the loadings might be too high for these windows. It might be OK but it might not.

OR - alternatively - have the window company confirm in writing that the windows are structurally sufficient for your specific house

Agreed, Thank you all for your input. Any ideas on the cost of having a wind load calculation carried out?

Calahonda52

wazzoraybelle wrote: »

Agreed, Thank you all for your input. Any ideas on the cost of having a wind load calculation carried out?

I would be more concerned that the spec for any such report is properly flagged so you need to be very specific about what you want answered.

In passing, fired up iTunes this am, on random play, and guess who was first up:

2nd verse

Yes, how many years can a mountain exist
Before it's washed to the sea ?
Yes, how many years can some people exist
Before they're allowed to be free ?
Yes, how many times can a man turn his head
Pretending he just doesn't see ?
The answer my friend is blowin' in the wind
The answer is blowin' in the wind.

Keep well.

Metric Tensor

wazzoraybelle wrote: »

Agreed, Thank you all for your input. Any ideas on the cost of having a wind load calculation carried out?

Having the calculation carried out on it's own would not be too expensive. It would take an engineer a few hours - or maybe a day if he was giving you precise wind-loading values on a range of different surfaces across the building.

However - as CH says - as a stand-alone service I don't know if it's much use to you because one needs to know what to do with the calculated figures when one gets them! It should be part of a larger service you are purchasing from the Engineer.

sydthebeat

Metric Tensor wrote: »

Having the calculation carried out on it's own would not be too expensive. It would take an engineer a few hours - or maybe a day if he was giving you precise wind-loading values on a range of different surfaces across the building.

However - as CH says - as a stand-alone service I don't know if it's much use to you because one needs to know what to do with the calculated figures when one gets them! It should be part of a larger service you are purchasing from the Engineer.

SEAI provide wind speed information for ireland

http://www.seai.ie/Renewables/Wind_Energy/Wind_Maps/

Metric Tensor

So does IS EN 1991 syd - and you have to run the wind speed through a range of calculations to determine the loadings (both positive and suction) on the various parts of the building.

It's not just a matter of multiplying the wind speed by a factor - the site orography, shape and height of the building, distance from the coast, pitch of roof, etc. all come into it.

sydthebeat

Metric Tensor wrote: »

So does IS EN 1991 syd - and you have to run the wind speed through a range of calculations to determine the loadings (both positive and suction) on the various parts of the building.

It's not just a matter of multiplying the wind speed by a factor - the site orography, shape and height of the building, distance from the coast, pitch of roof, etc. all come into it.

i suppose i was just assuming an engineer wouldnt have to site visit to do those calculations. Its certainly an area im not well up in

Metric Tensor

No site visit necessary in the majority of cases - confirmed!

Calahonda52

http://www.independent.ie/life/lighthouse-lodgings-on-rugged-wild-atlantic-way-coastline-could-be-yours-for-130k-34870218.html

If I recall correctly the OP is working on a lighthouse: is this it

wazzoraybelle

Nope, not this one. Beautiful building though!!

Calahonda52

wazzoraybelle wrote: »

Nope, not this one. Beautiful building though!!

His and Hers when the snoring keep you awake in a Force 12

Keep well