Holdfast Training Services Trial Blog

There is a genuine BP post on the way, just as soon as I finish this TMR…until then some comments on the following would be appreciated. I have been providing some engineering advice to my old housing association in Woolwich over the last 3 or 4 years. Over Christmas there was a roof leak in one of the upstairs flats caused by the structural failure of a roof air vent as per the pictures below.

The only thing holding the vent in place was the lead flashing which, under wind loading, has failed quite catastrophically as can been seen above and below.

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Below is an example of the stack arrangements on the roof, the third stack in is identical to the failed one and is clearly already starting to buckle.

Below are pictures from the front and side of the development. The stacks are positioned in the valleys of the roof and can’t be seen in the photos, but it gives you an idea of the size and shape of the roof, the elevation in particular.

My first thought would be that stacks at this elevation, on a hill and overlooking the Thames and a lot of flat space, would be subject to near constant wind loading. I would have expected something a little more robust holding them to the vertical than a few mm of lead flashing. However, I am not expert in roofing design and my first assumption is that this would be a standard building practice that, in this case, should have avoided/improved upon by the architect/site engineer. I have advised the Residents Association request that Gallions inspect the remaining flues and vents as I am sure that this is going to be an issue common to most of them (especially going on the jaunty angles in the photos). 

There is mounting evidence that the developer has cut numerous corners, which the housing association (Gallions, now Peabody) failed to pick up on when taking over the building on completion. I am interested in your views as to whether this would be another one…