Should we attach plywood to large west-facing windows in storm?

[LinearPancakes]

In the recent winds, we noticed a lot of bending on our large triple glazed panels. 1x aluminium framed window 2360x1550, 2x Internorm sliding door panels 2320x2100. We're mostly west facing, so getting a lot of direct wind in storms. We were up to 54mph gusts last night, though it has been higher in previous years.

 

Obviously they're designed to flex, but it does make me wonder how much they'll withstand and what impact it will have on the containment of the gasses. It was pretty worrying to see.

 

Most aspects of the building structure are designed/checked by the structural engineer, but I don't think anyone really owns checking these details. We specified the size, the window company supplied them.

 

Any idea where I can see what the maximum rating should be?

 

We could make some marine plywood sheets to fit externally in extreme cases, but the frames are aluminium and I wouldn't want to be screwing into that.

Edited January 22 by LinearPancakes

[craig]

I use https://skyciv.com/wind-load-calculator/ and https://www.omnicalculator.com/physics/wind-load / https://www.omnicalculator.com/physics/air-density

 

I tend to enter the data into skyciv, then obtain the m/s and enter the m2 of the unit and assess the glass and unit requirements based on those results. I do have a program being built specifically for this but at the moment this is what we use. It is then for your SE to check this data and sign off (in Scotland it is becoming more and more common that is information is being requested for form Q).

 

The glass size should be within the sizes defined these tables. Although it shows double, it only refers to the inner and outer panes in triple glazed units.

Edited January 22 by craig

[JohnMo]

We are in a high wind area and all our windows were subject to structural approval. Take a look at the allowable deflection - quite surprising 

 

 

 

[craig]

@JohnMo Do you mind me asking what program that is?

[JohnMo]

20 minutes ago, craig said:

@JohnMo Do you mind me asking what program that is?

Sorry no clue, the window supplies provided the information to our structural engineer and I was copied on the email.

[Kelvin]

It looks either written in house or it’s the front end of a spreadsheet. 

[craig]

30 minutes ago, JohnMo said:

Sorry no clue, the window supplies provided the information to our structural engineer and I was copied on the email.

 

Thanks, I'm writing our own one at the moment in excel purely for our benefit, as getting these calcs can be a nightmare at times.

 

4 minutes ago, Kelvin said:

It looks either written in house or it’s the front end of a spreadsheet. 

 

You'd think that by looking at it but some of these programs are still stuck in the 80s 😉😂

Edited January 23 by craig

[JohnMo]

Just been back through the email trail and the data came directly from the glass supplier 

[LinearPancakes]

Thanks guys, I'll have a dig into those numbers. Sounds like the window supplier should have requested we co-ordinate with the SE, given the size of the panes involved? I guess if there's no regs for it, they'll not volunteer to do that.

 

I admit it's just not something I'd thought about until I saw the reflections shift on the glass.

[Conor]

Are the windows internorm as well? For our 2.4x2m window, they specced it with the thicker frame and 40mm glazing unit. It's toughened as well, it's not going anywhere. Yours should be the same as it was done automatically through the specifying software they use.

 

[LinearPancakes]

Thanks @Conor. I've asked for details on this topic from the window supplier. I'll report back what I find out.

 

Hopefully, as you say, the software they used to spec out the Internorm lift & slide would have taken these things into account. The frame on the slider certainly is chunky, so not worried about the frame.

The window is unfortunately not Internorm; one of the few aluminium frame windows in our build. Still triple glazed - not sure how much the layers will help, presumably a bit.

[LinearPancakes]

Obviously the window supplier said it will be fine, and referenced how they'd seen videos of this type of toughened glass bending like a banana before it cracked. They also cited previous installation of the lift & slide in costal areas with high winds.

 

So I think the weak spot is probably the separate single window, as it has a thin aluminium frame and is not internorm, so will not have been through the same design verification process.

 

I'll try to just not worry about it. Unless I hear of 80+ mph gusts coming, in which case I may try to find a way to fit some OSB to the outside of the single panel window. 😅

[LinearPancakes]

Or.., given the challenge of installing OSB (nowhere to fix it to), a suitable size & thickness of celotex might be a good option. Could tape it to frames, side window without damage. It should help take the edge off the forces/deflection and would protect the glass from anything flying around too. 🤔

[Nick Thomas]

You could go for proper window shutters and make a feature of it? Internally or externally. I used to dream of that regularly up in the Shetland house, with 80mph winds rattling the glass ^^.

 

Random pic off t'internet