My experience of Harris and Sons Windows 

Photos of roof Harris and Sons Windows said  they had no doubts would pass building regs and had no leak issues
After being unsatified with Harris and Sons Windows response the roof was inspected by a building inspector
As a result of multiple building regulation failures the whole roof had to be removed and the inspector advised i find a suitable
competent contractor and not to let Harris and Sons return, he then went on to ask about who fitted the windows and if they were signed off.
You have to question Harris and sons windows and the fitters understanding of building regulations

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