wet insulation in cavity of new build

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the house was built 12 months ago but i could not finish the interior due to insufficient funds . The walls are 4 inch concrete blocks the cavity is 4 inch pumped with a wool type insulation . the windows were fited by a fensa reg company and the walls and reviels were rendered using waterproofer in the scratch coat finished with pebbledash . the roof was covered with tyvec and spanish slate . I noticed a damp patch on the inside wall of the house , south facing wall . At first i thought it was a problem with the cavity closer around the window or possibly the damp course above the catnic lintel . After removing a small section of blockwork i discovered to my horror that the cavity insulation was soacking wet . I did 2 more inspection holes and the problem was the same .
I have read about INTERSTITIAL CONDENSATION and WARM FRONT CONDENSATION COULD THIS BEE THE CAUSE . PLEASE CAN ANYONE HELP AS I NEED TO MOVE IN TO THE HOUSE AS SOON AS POSSIBLE
 
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Have you got air bricks fitted and is your cavity free from insulation in your loft ( inner /outer leaf) to allow air flow.
 
I was thinking:

Rain

No cavity tray

Torn or badly fitted roofing felt allowing water to get into cavity

Are you sure the cavity was dry when you put the roof on? Does it have weep holes? If not it could have been deep with water lying on the DPC or concrete infill at the bottom of the wall.

If the house has not been occupied hence unheated then I would not have expected interstital condensation.

But if it has recently had a lot of wet work done (plastering, screeding) then the house would have been very moist inside.

p.s. if no weeps, put some in.
 
the house was built during the summer . no rain fell during constriction of walls roof or during plastering . there are cavity trays the cavity has been closed at roof level and the render is sound in ther being no cracks due to movement or shrinkage .
 
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there is also a radon trap with weeping holes plus damp course above . The tivec and slates are not leeking .
Maybe the driving rain is causing the problem but as i stated erlier the scratchcoat contained the recomended amount of waterproofer .
 
I meant weep holes just above the dpc, to let out any water lying in the cavity.

It is unusual for rain to penetrate a wall, unless through damaged brickwork, badly detailed lintels, windowframes or something.

Very occasionally a pipe can have a leak where it passes through a wall.

Sometimes a leaking downpipe can let water in where the wall has been damaged, this is more common on older houses with cast iron pipes and big nails through lugs.
 
whatever the problem, if the house was built 12 months ago aren't you covered under a builders code have a inspector check it out and have building contractor repair his cost
 
the house is a self build . i am responsible for any defects . I was involved in the building process . to the best of my knowledge the work was done in a very profesional manner . THE CAVITY WAS WASHED / HOSED EVERY EVENING TO ENSURE THAT NO MORTAR WAS ON THE WALL TIES , THE EXESS WATER DRAINING OUT THROUGH WEEPING HOLES .
I JUST CANNOT BELIEVE THAT THE RAIN IS SEEPING IN THROUGH THE WATERPROOFED clading AND INTO THE CAVITY . aS I STATED EARLlIER THE WINDOWS WERE FITTED BY A FENSA REGISTERED CONTRACTOR AND THE ROOF IS WATERTIGHT .
 
steady on old chap!

CAPLOCK.jpg
 

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