So these two roofs in Creekmore Dorset looke d like they were in good shape from the outside However if you went into the loft it was a different story with more holes in the felyt than a tetley tea bag it was time to strip off and renew. The tiles a stonewold mini get clogged channels with moss and then when the heavy rain comes they cant handle the rain and can overspill onto the undersarking felt which is designedas a secondary emergency barrier to help maintain waterproofing ntegrity. these roofs had been built in the 1960s, so about 50 to 60 years ago. The tiles when taken off were cleaned up and re used
We used a breathable membrane from Cromar along with tannerlised 50mm by 25mm roof battens fitted out at the gauge for Stonewold Mini roof tiles.. These are a heavy concrete interlocking tile that are clipped periodically.