# Damp issues after house cavity insulated



## Logo (18 Jul 2017)

My house walls were cavity insulated by a company about 7 years ago. Recently I've noticed dampness on walls that weren't damp for the previous 25 years. Also a visible black staining on an external wall mid-building that definitely wasn't present over the previous 25 years that I lived in the house. Do I have any redress with the company?


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## peemac (18 Jul 2017)

Best to find what the cause of the damp is before assuming its the insulation. 

Is the house properly ventilated?


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## odyssey06 (19 Jul 2017)

Some interesting similar queries online...
http://www.telegraph.co.uk/finance/...-wall-insulation-so-why-is-my-house-damp.html
http://www.which.co.uk/reviews/insu...sulation/cavity-wall-insulation-damp-problems

Peemac, if proper ventilation is the root cause, can you clarify possible reasons why - if there was no dampness in the house 7 years ago - it could now be the issue?
Seems like something else has to have changed - either the cavity insulation or else some other damage to the property is now allowing dampness in or else the property has become more exposed to the elements.


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## Easeler (19 Jul 2017)

Was thinking of getting this done myself but don't know what cavity is like there is an insulated slab on wall already. I have heard that it can cause dampness,, had a water leek in house myself turned out to be a crack in bathtub,a small leak under floor can do serious damage to property if not detected in time.


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## Leo (19 Jul 2017)

odyssey06 said:


> Peemac, if proper ventilation is the root cause, can you clarify possible reasons why - if there was no dampness in the house 7 years ago - it could now be the issue?



Prior to installing cavity insulation, many houses have a myriad of drafts and air leakage points that facilitate regular air changes so that moisture does not build up within the house. When you install cavity insulation you usually significantly increase the air-tightness of the house and need to compensate by adding increased ventilation.


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## odyssey06 (19 Jul 2017)

Leo said:


> Prior to installing cavity insulation, many houses have a myriad of drafts and air leakage points that facilitate regular air changes so that moisture does not build up within the house. When you install cavity insulation you usually significantly increase the air-tightness of the house and need to compensate by adding increased ventilation.



That makes sense... but in light of this, is there a case that the company who put in the insulation should have bench-checked the house for adequate ventilation and potentially recommended increased ventilation ?
I'm guessing after this elapsed time, even if they should have done so, hoping for any redress from the company would be overly optimistic...


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## PaddyBloggit (19 Jul 2017)

Surely vents would have been installed as part of the process?


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## noproblem (19 Jul 2017)

Logo, 
Could you be a bit more specific about the staining? Where it is happening on the walls, is the house 2 storey, bungalow, a dormer, etc. Is it overshadowed by trees, are gutters cleaned, etc, etc?


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## Leo (19 Jul 2017)

Some of the more reputable companies may warn you of the need to install vents, or guide you in the current building regs and how to comply with minimum ventilation requirements, but I'd bet most won't. 

You contract them to do insulation, they do insulation. That suits them as any issues with condensation or damp down the line they can blame on inadequate ventilation, and as they were only contracted t do insulation, that's not their problem.


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## Logo (19 Jul 2017)

noproblem said:


> Could you be a bit more specific about the staining? Where it is happening on the walls, is the house 2 storey, bungalow, a dormer, etc. Is it overshadowed by trees, are gutters cleaned, etc, etc?


The house is two-storey and it's an external blackish staining in one spot just above the first floor. There are no trees over-shadowing the building and the gutters were cleaned last year. I will check the gutters again and I'm thinking of spraying the darkened area with a dilute chloras solution.


Leo said:


> When you install cavity insulation you usually significantly increase the air-tightness of the house and need to compensate by adding increased ventilation.


This is possibly true because the ventilation wasn't increased after insulation.


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## michaelm (19 Jul 2017)

My neighbour got cavity insulation about 5 years ago and the company increased the size of all the vents at the time.  SEAI offered to pay for cavity insulation on my house but I didn't take up the offer as mine faces west and I had concerns that it may lead to a dampness issue down the line.


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## bren1916 (19 Jul 2017)

I experienced some similar issues when I had the cavity walls pumped with insulation beads back in 2005/6. It certainly is a conundrum whereby increasing the thermal performance of the structure can result in the requirement for increased ventilation! 
Try reducing the following occurrences which result in condensation forming on cold spots on wall/ceiling; 
1. Drying damp clothes on radiators, 
2. Keep bathroom & ensuite doors closed and extractor fan on/window open after shower/bath to remove moist air.

If the damp patch is lower down the wall - perhaps check for cracks in the external pointing or render which may be letting in water.


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## Eithneangela (20 Jul 2017)

Recently had cavity wall and attic insulation installed under SEAI scheme. Installation company insisted on installation of new air vent in wall in living room which has a fireplace in it. Said it was part of SEAI rules. Very happy with result, house stays warmer longer after heat on for a short while.


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