Damp - Since Cavity Wall Insulation Injected

[shankton]

I did not want to jump in to the many other threads about RD so am starting my own little debate.

It suggested that I have the cavity cleared out on the external side wall, being naive I thought this simply meant clearing out the air bricks, I now realise it probably meant more.

Anyway I cleared the air bricks and got a grant to have cavity wall insulation injected this has been in place for about a year. I am now noticing that the 2 external walls along the side of the house are showing signs of damp.

Could this be a cause of the wall insulation and what are the chances of me having it treated under the 25r year guarantee?

 

[JohnD]

Damp on the inside or the outside?

Is there black mildew or green moss or yellow lichen?

How high up the walls do you see it? What is the shape of the damp patches (round, flat, triangular?)

How far above the outside ground is the damp course? Is it bridgesd by soil or anything?

Are your ground floors wood or concrete?

We like photos.

 

[shankton]

I know it has been a while since I first posted am hoping people can still help now I have got the information and time to hand.

Damp on the inside or the outside?

Inside walls

Is there black mildew or green moss or yellow lichen?

It is more that paint has bubbled up see photos.

How high up the walls do you see it? What is the shape of the damp patches (round, flat, triangular?)

It starts just above the skirting board so about 6.5" and is round and bubbly.

How far above the outside ground is the damp course? Is it bridgesd by soil or anything?

The damp course is 1 brick high along the drive way which is the wall we are having problems with. Air brick is then bricks 2 and 3 at certain points along the wall.

Are your ground floors wood or concrete?

Wood

I will add photos in a while as digital camera has ran out of power.

 

[AndersonC]

Cavity bridging via mortar stuck to a wall tie? How big are the patches?

It may be that the CWI has reduced ventilation within the cavity so that any moisture travelling through a 'bridge' is not being dispersed.

 

[JohnD]

looks to me like blowing plaster. Can you put something in the picture to show scale, and stand back to show the damp as it relates to the skirting? How would you feel about knocking the plaster off to show us the bricks? You may want to buy a picture or something to put over the damage until smartened up again

I'd also suspect mortar snots on a wal tie, but this shouldn't matter if the outside wall is dry. Could there be a leaking gutter or anything outside? Or a pipe dripping e.g. in an upstairs bathroom?

If it is wall ties, it would be possible to remove just a couple of bricks, clean it off, and re-mortar them back in. Unless you are a very neat bricklayer you could do it from the inside as (1) the wet plaster will need to be taken off and redecorated anyway (2) any scruffy mortar joint will not show.

If you have a lot of bad wall ties, you will need a builder to scaffold up and cut then out from th outside and use new stainles ties (there are modern machines for cutting out bricks by the mortar joints, which are fairly clean and quick)

 

[shankton]

On the second picture you can just see a cable running along the top of the skirting this is all just above the skirting level. I will take more pictures this evening as not got them handy at the moment. As for pipes leaking there are none which run directly above this wall and any pipes upstairs all run parallel to the wall on about 10ft away from it.

There are cables running down the wall on the outside but again these are a lot higher up than these patches.

I am planning on getting this all hacked off and plastered shortly will try and get some pictures of the brickwork when this is done. Should it be left open to dry out once hacked off?