Can cavity wall insulation cause dampness?

Therese1

Interested to hear if anyone else has had problems with dampness following cavity wall insulation?

I got mine done in 2005 and just before Christmas this year I noticed two large patches of damp and dirty marks on the wallpaper on my gable end wall. I finally traced the installers (not easy) and they sent a surveyor to look at the damage a couple of weeks ago.

He left saying he needed to speak to a manager and would get back to me the next day (I asked but he wouldnt say what caused the problem).

Several phone calls later (me chasing and all sorts of promises to get back to me!) I was then told "oh, you have an appointment booked in for the insulation to be redone on 15 March"?? eh, who was going to tell me this; did the date suit me etc etc??:mad:

Anyway, still no comment on what has caused the damp patch and damaged wallpaper.

several questions:
will them redoing the insulation solve the damp problem?

how do I get rid of the damp thats already there?

can I get them to pay for the damp work and repapering? This is the hall and stairs - so will they pay to repaper the whole hall upstairs and down?? Do I have to let them do the papering or can I get someone else to do it and send them the bill (are they decorators as well as insulators??) I had got decorators in to do the hall because of the high ceilings - about 1.5 years ago.

anotherbaldrick

They need to remove some external bricks and scrape off the mortar droppings from the wall ties . These droppings are an inheritance from the original builder who should have cleaned them as the wall was built up The mortar build up on the ties allows them to conduct moisture over the cavity. The insulation contractors should have checked the ties were clean before they pumped in the insulation Naughty, naughty.

Therese1

Thanks Baldrick! That explains some of it for me... But hope you don't mind me asking more?!

House was built 1930's or 40's ex council semi. Presume it was breeze block originally and was rendered later?

So if they redo the insulation by just filling it up more will the problem reoccur? If so do I just say no thanks? Or what should I ask them to do to prevent another episode?

tony6403

More likely to be voids causing condensation where warm air meets cold (uninsulated ) surface.
If the wall ties are coated in mortar your property might have been subject to damp before insulating the cavity. Never seen brickwork removed to check wall ties before insulating.

Therese1

Thanks Tony,

but why would the damp suddenly appear now - and spread so quickly - the wallpaper is very stained and its even penetrating the cornicing quite deeply?

Leif

Have you checked for other causes of damp, such as a blocked drain pipe? I know little about damp, so hopefully someone else might give you further suggestions. If the insulation has been okay for over 6 years, that does raise the question of why it has now gone awry.

iamcornholio

CWI can highlight an existing condensation problem

You need to be clear whether this "damp" is penetrating or condensation

swift1_2

We've got damp on our bedroom wall just below window in the corner. Recently had the loft insulated, they said the walls already had insulation in them. Asked them what could be causing the damp, they reckon over time a gap has formed around that area of the wall and thus when warm hits that area which is cold it condensates hence the damp. He recommended either getting it checked and filled again or putting in an air vent.

patman99

What sort on cavity insulation did they use ?. The two-pack foam one is known to break-down and act like a giant spong over 25 years or so, but the blown-fibreglass stuff tends to be stable and allows a slight up-current of air in the cavity.

tony6403

Therese1 wrote: »

Thanks Tony,

but why would the damp suddenly appear now - and spread so quickly - the wallpaper is very stained and its even penetrating the cornicing quite deeply?

If you have rockwool type insulation it is possible that it has slumped and created a cold spot which will attract condensation.
If you have polybead insulation which didn't have adhesive applied as it was installed, the beads could be escaping (sometimes under the ground floor where the odd bed joint or vertical joint in the unseen internal brickwork has small gaps). This will allow the beads to fall producing voids higher up.
It may be that your insulation is fine and that you have other problems such as displaced roof tile(s) or leaking gutters.
I would let the company sort out any insulation issues and then ask if they intend to redecorate.

rebecca1974

I would have them drill a hole and check the areas with a borescope to see if voids are causing the problem. Thermal imaging doesn't cost the earth and would also spot missing areas of insulation a mile away, if they fail to solve the problem have this done then for proof and go back to the company with proof that the insulation has caused these issues. All cavity installation work must adhere to the ciga rules so contact ciga, easily found on google.

regards