I am planning to replace the original fascias and soffits on my house, whic h was built in 1994. Several companies have provided estimates and have spe cified ventilation equivalent to a 10mm continuous gap, in accordance with the current building regulations. However, I believe the original soffits h ave more ventilation than this. The soffits have rectangular ventilation sl ots at regular intervals. Each 61 cm along the length of the soffit has a 2
2 cm long ventilation slot, and each slot is 48mm wide. This is equivalent to (22/61)x48 = 17 mm continuous gap. Although there will be a correction factor to take account of the fact that the slots have a wire mesh grille, I suspect the ventilation is still more than the equivalent of a 10mm cont inuous gap.A few years ago, I had trouble with condensation forming in the loft in col d weather. I reduced the problem significantly by fitting a tighter-fitting loft-hatch and sealing around pipes/cables where they enter the loft from the rooms below. Now only a few drops of condensation form on the roofing f elt in cold weather. However, I do not want to aggravate condensation issue s by having new soffits/fascias that provide less ventilation than the exis ting ones. Therefore I'm thinking of either (i) using soffits that provide ventilation equivalent to a 25mm continuous gap, or (ii) using soffits that provide ventilation equivalent to a 10mm continuous gap plus over-fascia v entilation that provides ventilation equivalent to an additional 10mm conti nuous gap.
I'd be grateful for any comments about whether (i) or (ii) above sound sens ible, or if there are any reasons why I should not use these options
thanks
John