Nightmares: a calm analysis

[ToughButterCup]

Time for a calm analysis of what happened here. If you haven't read the original post, please do so now: it explains a good deal of what I say below.

 

The weather.

That night, it was foul. 30mph+ steady wind and gusting up to 50. I know that at low level it was gusting at 40 + because our plastic guttering rattles at that speed or thereabout. In addition, there's a hiss in the phone wires which (I have tinnitus) is very very close to the pitch I hear in my head all the time. So, background noise instead of cancelling out (or distracting from) my tinnitus was accentuated for the odd second or two in the heavier gusts. 

 

The key determinant in the collapse was direction. Here's the view due east

(from the top of the scaffold looking eastward)

Those hills are the Pennines. Looking to the skyline on the right thats 100 meters away from Forton Services on the M6. The gap in the hills is the Trough of Bowland. The Hills on the left are Clougha and Ward Stone. The wind was from the east that night. Just out of sight between the pond and the hedge is a steep slope. Perfect to create a pressure wave suitable for a slope-soaring glider.

 

By contrast look at our view West

 

 

The view from the site westward. Four fields away is Morecambe Bay.  

Look at those wonderful energy absorption systems. Trees.

 

I make this post because of what happened last night. Sailors, hill walkers, glider pilots, GA pilots will understand this all too well.

 

A vicious thunderstorm went through at 21.30 last night. Preceded by a gust front from the west that would have done justice to a small jet engine. It hit the house with a sickening thud, instantly rattled the guttering, and I shot out of bed. Still half asleep I stumbled out into the rain hail and thunder with Debbie's calm words ringing in my ears..

 

"What do you think you can  do about it?"

 

Rushed into the container, dug out my laser plumb line and set it up to see if the blocks were moving. By the time I had fiddled, cursed fallen over, smacked my cheek on the door, trodden on the cat (bless him) woken the dogs and got the laser setup, the wind was abating, but it was hissing down hard. I could see the back edge of the front clearly delineated out to the west in the last of the failing sunlight.

 

Standing out in the open in front of Salamander Cottage hardly a breath of air on the ground, the tops of the trees' west side were still rattling loudly. 10 minutes later, not a breath of wind anywhere.

 

Wind direction matters. Wind strength matters. Local topography matters. Especially when a builder doesn't see the wider picture.

[Ian]

@recoveringacademic

Local topography can be so important when it comes to wind!

 

I grew up on the north west coast a little further south of you and know how bad the prevailing wind off the sea can be anywhere near the beach - you'd normally expect the danger to be from the west but your photos eloquently demonstrate the problem you had that night.

 

Did you ever read about the 1960s failure of the concrete cooling towers at Ferrybridge?:

https://matzagusto.wordpress.com/2011/12/14/vibration-damages-towers-case-ferrybridge-cooling-towers-collapse/

 

It's a prime example of the dangers that can be caused by wind being channeled and the unexpected loads that it can create on structures.

 

Ian

[ToughButterCup]

@Ian, I have always been fascinated by microclimate; from competitive sailing (reading subtle changes in waves), competitive fell running (finding a few of competitors running in my wind shadow), to the downright terror of landing microlights in wind sheer . 

Never thought it would all come into sharp focus on a house build....

[ProDave]

I'm even more confused now what the root "issue" is?

 

Did the builders build the wall wonky? Or did the storm move it before the mortar was set?

[ToughButterCup]

Root issue: there isn't one: there are many interacting with one another.

High Wind and higher gust speeds. Lack of experience. Failure to communicate. Assumption of common sense. The pressure to take on too much work. 

 

The two other stakeholders would put a different emphasis on it. One would say; use your common sense and don't build too much height before pouring. The other would say; but you didn't tell us that.

Had the wall been poured, and the concrete set, there would have been no problem.

 

It is crystal clear to me that neither builder nor producer has been trained to communicate well. They do what they do. They don't listen well. They don't express themselves clearly. They rely on what is called common sense. But  common sense isn't universal. Add a trusting (yes, naive - but not so naive now)  Domestic Client , unseasonal turbulent wind coming directly out of the east (very rare here), a builder who is trying to do too much, and you've got an issue.

 

And here's what's happening next. The replacement blocks are arriving tomorrow morning, (sensible rebate on that) and the builder is going to rebuild for free. Exactly as @Declan52 said it should last week.

 

 

[SteamyTea]

On 27 July 2017 at 13:06, recoveringacademic said:

I have always been fascinated by microclimate

Did the wind 'run down the motorway' by any chance.

 

I went to do some work on the Reigate section of the M25, was a lovely day, except on where I was working, the wind was really strong.

At one of the colleges I was at there was a tower block ( @JSHarris knows it).

Between the hairdressing department, the science block and that tower, the wind blows at least twice the normal windspeed.

[Stones]

@recoveringacademic, I can certainly empathize with you about the impact wind / wind speed has had on your build. 

 

Living somewhere with a near constant 15 - 20 mph breeze, frequent blasts of stronger winds and accompanying squalls coming off the Atlantic or North Sea, then building in an elevated position has given me a great respect for the construction community up here.  Of course they don't have much choice but to get on with it, and simply adapt how and what they do to accommodate the weather.  

 

I'll readily admit to being more than a little concerned when our ICF blocks were taken up to wall plate height.  I had visions of polystyrene blocks being blown half way across the county.  I was fortunate, the weather was reasonable (for Orkney) and my builder is seasoned and experienced with the ICF system we used.  He cut his teeth with ICF on his own house, and has been perfecting ever since.  

 

Whilst there will always be weather events which exceed predictions, and consequent damage to partly built structures due to their inherent vulnerability (a timber frame build was wrenched / twisted of the sole plate in one instance up here) experience of using a particular build system or method and mitigating risk is an important part of any build.  Training of course is a good start, but nothing will ever beat gaining years of on the job experience.  

 

It's been a painful lesson, but one which you, your builder and others through the forum will learn by, and you will come out stronger for the rest of the build.  

 

Good to hear that replacement blocks are on their way and the builder will remediate. 

[vfrdave]

I can relate to this, I lost 4 block piers that hadn't been backed up because of other failings that the contractor had made (who also took on too much work and didn't really have the time for mine, he is now gone) one evening when we had 40mph gusts. They had stood for 3 weeks prior to this. 

 

It made me realise the power of the wind and put into perspective the wind posts for my walls and block on its flat inside skin that the SE specified to account for wind loading.