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Roof leak question

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cr0

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Hello,

We have a 35 year old house still with its original double roman concrete tile roof, until now we've not experienced any issues with leaks. However I've just been up in the loft and noticed multiple lines of wetness in the the loft insulation below the roof, the lines run along the length ie across the trusses and in the odd place there are still 5-10mm puddles so clearly some water got in (this is now two weeks after we had some torrential rain). The ingress of water, the lines seem pretty uniform over the whole roof space (odd bit without and worse to the rear than the front of the roof).

I've checked from outside and noticed there maybe the starting of some gaps in the mortar between the ridge tiles, could this explain it? or is it that the roofing underlay is reaching the end of its life? or maybe a bit of both or something else I'm not thinking of.

I am obviously going to get some roofing firms in to quote but I wouldn't mind the views of the knowledgeable folks on here.

Thanks,
Robert
 
cr0 said:
I am obviously going to get some roofing firms in to quote but I wouldn't mind the views of the knowledgeable folks on here.
Click to expand...

Where are you, has it been exceptionally cold there, and might it be condensation, on a very cold underside of your roof?
 
Thanks for the replies.

We've been waiting for some more rain to come so we can check, so far nought but it looks like there may be some rain coming in a day or two.

We're in the south east of England in Kent so the lowest temp. where we are according to my temperature sensor has been 2C. It's a cold loft I think you call it with vents in the soffits and a reasonable air flow, there is about 300mm of mineral wool insulation laid down covering everything apart from one small area of flooring with 150mm mineral wool insulation underneath it and the insulated cold water storage tank which has no insulation beneath it to allow a little bit of warmth up to protect the tank from freezing.

At this time of year it's always significantly colder when we go up there than the main house, would you still expect to get condensation or rather enough to create the wet lines?
 
Cold air at this time of year can have over 80% moisture. The slightly warmer cold air in the loft meeting the cold felt/membrane cooled by the colder air outside is an almost guarantee of some condensation occurring. The ventilation is bringing in humid air

Ventilation will not stop condensation. The purpose is to stop mould fungus.

Check out the cars outside on a cold night. Look at that condensation on the outside of the windows and bodywork. You won't get a more ventilated place than outside.
 
Could be driving horisontal rain, that's what I thought in my case, everything looked cushty so I placed a plastic flabby board to the underlay to direct the water down and above the underlay. 3 years later I found out a ridge tile was cracked under the moss. The whole time water had been running above the underlay, luckily my plastic set up preventing it leaking to the loft.
 

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