Cwi blown mineral wool

[martysmarty]

Evening!
As i love adding to my never ending list of jobs on this kitchen extension plan, i have uncovered other potential problems with the existing structure of the house.

When we removed the plaster from the kitchen and downstairs wc, the plasterboard was really damp and dropped to bits in places. It was worse in the downstairs toilet but tiles were hiding it. Popped off the plasterboard and the bricks looked dark above slate dpc.

I decided to pop a brick out one course abouve dpc on the inner leaf, and found the cavity insulation to be binded with mortar dust and god knows what else right down from lean cavity fill up past dpc

I decided to vacuum the cavity out 150mm below dpc to clear it. Now its left me thinking, have i got issues due to the mineral wool done in the 90s, or was it just the fact it was down past the dpc to cavity fill level.

I stuck my hand up the cavity, i felt some wet spots up there, but as i lost some insulation i couldnt get my hand far enough up to see.

About 2 years ago i had to lower the driveway as the ground was up to damp level as it was bridged, and also remove 2 rubble bags of mortar and bricks out my cavity at the door reveal!

Should i get this stuff sucked out??

 

[martysmarty]

More info, thinking about it.

The wall on the oposite side of the toiet, (internal) was a single skin bricked wall, this also had quite bad damp. Not sure yet if theres a slate dpc in it as i cant see below the concrete slab. The slab was poured around the wall, so i dont know much about this wall till we knock it out, as thats the plan anyway

2, theres a clay pipe in the floor to the toilet. One of only two clay pipes left in the house. Its being removed when i dig the floor up but this is very close to the wall, and theres the white salts on the bricks.

3, further up towards the front of the house is a svp stack. It weeps at the connection near the rest bend. Again not got round to sorting it. could this cause it? Its about 4 meters away

 

[JohnD]

You have a source of water. CWI does not create water. Is the water coming from a leak, in pipe, drain, roof or gutter? Is it entering the wall as rainwater through defects in the brickwork or around windowframes? Or is it condensation due to excessive water vapour in one or more rooms, perhaps due to steamy showers or an unseen leak, for example in the floor?

The two rooms you mention are the kitchen and downstairs wc. Both contain waterpipes and drains.

When you find and rectify the source of water, I'll wager that your damp will go.

 

[martysmarty]

So its not really to blame the fact its mineral wool.

The wool dropped below dpc line, is this a problem? I know on new builds they spec insulation below dpc on some builds but thats different type of insulation and i dont think it draws up water like this stuff can.

Gutterings are ok, granted they were leaking last year.

Brick work is pretty shoddy outside. Some spalled faces from previously leaked gutterings, i actually kept some old bricks back when i knocked out the back of the house to replace these.

Theres also a window right in this location..

Looks like i will have to check these out first

 

[JohnD]

I don't know about yours, but when mine was done, there was some waste blown into gaps in the blockwork where plumbers had worked. I swept it up and put it in a bucket outside. Some time later, I noticed the bucket was full of water and scooped out the wool.

By the time it hit the ground it was dry. Water just fell straight through. It was not absorbent like cotton wool. I believe the fibres are treated to repel water.

 

[martysmarty]

Took a deeper look today.

The cavity was completly bridged by 2 bricks above inner dpc with broken down mortar, sandy stuff, rubble, crap all mixed with insulation..

I pulled a few bits of insulation out at floor level a few more bricks along and although it was a little moist in places it was by no means soaking. And the insulation appears to be in good order.

What i didnt notice last night was that the inner dpc was actually one course of bricks lower than the outside. So when i thought i had cleared a lot out, there was still a lot more to go!

I will get some pics up as i took some of before and after

 

[JohnD]

I have a builders canister vac, and poked the tube down the cavity to suck out sand, snots and broken brick. It can lift a half brick. The metal tube will loosen or break up blobs of mortar

 

[martysmarty]

hey john, i got the good old henry out mate. it's doing the job well but blocks up a few times with the big stuff. filled quite a few hoover bags.

here's a few pictures. to be honest they dont do it justice for how filled it was. bear in mind the slate that you can see, is the outer skin, as it's higher up. the inside DPC is a brick down at least, so it was filled good and proper!

i am still a little worried about insulation dropping down below again but to be honest, its not really insulation alone i have sucked up. its pretty much broken down mortar and snots/ old plasterboard.

There's a badly corroded wall tie in there. i have not seen one that bad anywhere else in the house so far

 

[JohnD]

quite satisfying to see a spotlessly clean cavity.