We're about to undertake a large rendering programme in an effort to increase the SAP ratings on the properties concerned. I'm currently discussing how we deal with the issue surrounding boiler flues. If we render up to the flues then there's a chance we might have to increase the length of boiler flues. There is no specific requirement in part J rlating to the length of boiler flues and my view is that length of flue will be interpreted from manufacturers technical data. However I don't want to go down the road of altering flues and my preferred approach would be to place a larger collar round the flue and render up to the collar only. Does anyone know of a reason why this approach would be unacceptable? I'm posting this in the building and the Gas section because I'd be interested in getting both gas expertise and opinions from anyone who has encountered this problem during building works. Incidently we're using a 60mm phenolic insulation to comply with the new building regs requirements.
