2 May 2015

The Cowls

The cowls, the cowls, the cowls!  What a palaver.  This became the black hole of time and energy for the project.  We worked on this part of the build for months!!!  Had we known then what we know now, work on this should have begun months earlier - the beauty of hindsight!







Dimitri's favourite part of the original design were the metal window cowls. Early on in the design process we reviewed the designs with and without them and they gave the building such character. Not only do they look fantastic but they play a functional role in solar shading during the summer months when the sun is high.  It is critically important to prevent overheating in our highly insulated and airtight home. 




Without the cowls - an early design



Easy, we all thought, we'll make them from inexpensive Galvanised Steel sheet, fix them to the walls and then slate on top.  We were SO wrong!

As soon as the metal manufacturers were drafted in to consult on designs the issues became all too clear.  Galvanising is done normally by hot dipping steel in a zinc bath.  The zinc coating then protects the steel from rust, and even if the zinc coating is scratched then the remaining zinc will still prevent rusting.

The design of the cowls meant that sheets of metal would be the most straightforward thing to use, and cost effective.  However sheet metal is the worst material to hot-dip.  It has a high surface area to mass ratio and the heat related expansion during hot-dips results in warps, twists and buckles.  Oh no!

But luckily we discovered that it is possible to galvanise using another method where the zinc is sprayed on after the metal has been fabricated to the shape required.  There are obviously considerably higher costs associated with this - as always! 

Steel is very heavy, so aluminium was also considered as it is 1/3 of the density.  But aluminium is more expensive.  Believe me when I say this has not been easy and it wasn't inexpensive at all.  

It took weeks and weeks to get through all the decisions and get the final drawing package produced as all the windows had to be surveyed on site, checked, and checked again.  Then when we finally had the package we sent them out for prices and it took at least another month before we were finally in a position to be able to place the order.  The fabricators also had their own drawings to produce which then had to be checked by Team Luxton.  A complete headache for everyone.







I was promised a 3 week fabrication time and unfortunately 4 weeks later the company had still not obtained the raw sheet metal.  It would be another few weeks before we took delivery and then it was found that a couple of items were incorrect and so we had to wait for these to be collected and then re-fabricated...are you starting to feel the pain yet?  Drivers were ill, people were on holiday, workshops were busy, etc., etc.



Cowl parts waiting to be installed 



This created a real traffic jam

- without the cowls the slates couldn't go on
- the scaffolding couldn't be taken down until the slates were on
- all rainwater goods, hoppers and downpipes couldn't be fixed until the slates were on
- the parapet cover couldn't be installed until the slating was completed

It also almost left us homeless as we had given notice to our old home to move out in the last weeks of August, but with scaffolding surrounding the house we wouldn't be able to get the removals firm to enter the building!  In the end Andrew and I made a strategic decision to adjust the scaffolding and focus attention internally so that we could move in regardless, they would move outside at a later date when we knew everything needed would be on site.  Enough with the delays!








Cool after-school viewing better than TV!


We decided to leave the metal work raw and undressed, including the weld marks.  I love the honesty and character - very Wabi-Sabi!


Our scaffolding costs went through the roof as it had to be hired for another 6 months being no use in the meantime.  Had we known the extent of the delays it would have been cheaper to take the scaffolding down and re-erect at a later date.  

Once the metal work was mounted around the windows we had planned to get a welder to come and weld the separate pieces together.  Another new trade about which I know nothing.  My builder, Andrew, and my Structural Engineer, Charles, both expressed concerns about the wisdom of welding so close to our beautiful and expensive triple glazed windows.  These are powder coated aluminium and we don't want their coating to run off nor the glass to melt.  Another week or two of investigation and we solved the issue by only welding the outer edges.  








God bless my ever patient slaters, P.L. Allard, they had originally been organised for March, then delayed to May, then told that they would be able to start mid-August and finally got on site in September!







What can I say? Condensed like this it seems like a small hiccup but it ground everyone down and had negative consequences for the relationships and morale of everyone involved.  We got there in the end though! 






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