Wall is always damp in an area

[trevorbayliss]

I have a section of wall at the back of the house which never sees the sun.

The wall has been repointed and a window blocked up this summer.

Prior to this there was a hole in the wall higher up where the soil pipe was and the bath outlet pipe. These were open for quite a few months as the house was renovated. On two occasions we had a heavy rain and i think water tracked into these holes and it came through on the inside wall in the lounge (behind the blocked up window).

The inside is now dry, but the outside seems to get wet in the lower area behind the soil stack.

Any idea what could be the problem?

I don't think it is anything to do with the bridging of the damp course by the gravel area.

I don't think the soil pipe is an issue. I renewed the stack and place a new drain connector into the clay bend at the bottom of the stack.

Could it be an issue with the cavity insulation ?

Ideas appreciated

 

[vinn]

Water could be tracking down the wall or down the back of the soil pipe and hitting the s&c fillet at the string course of projecting brick? But my suspicion is that the moisture is coming up or penetrating through not coming down.

I dont see any cavity insulation injection holes - when the window frame was removed what kind of cavity insulation was exposed?

Where is the DPC - its best position is the bed below the air brick?
Where is your FFL?
Your ground level seems high - would it be possible to dig out & then pour a little concrete & bench it with a gentle slope towards the ACO drain?

Examine the interior wall and skirting very carefully for any signs of damp.
Did you thoroughly water test the new soil pipe connector to the rest bend?

 

[trevorbayliss]

The cavity insulation is the injected retro fit stuff.

DPC is just below the bottom of the air brick.

What is an FFL ?

I can dig out a little, but the reason why i installed the external drain in the floor was because the area up to the wall was all concrete and was damp. The area had been draining towards the wall. So i thought the channel in the concrete would solve this issue. Then just filled with gravel behind.

I didn't test the soil pipe or check for leaks at the connection in the ground, but did check on the stack Tee. I can easily pull back the gravel to have a look. I will have a check next week.

If you look higher up the photo, behind the soil pipe you can see some brick is also a bit wet there.

 

[theprinceofdarkness]

I would start off by trying to fix the higher damp spot. Its just below and to the left of the original brick lintel. Does the arch stick out a bit? If you have a Victorian sash window, their construction is very complex, and you don't know what has been left inside the wall especially as the wall has a cavity. One thing is certain, that spot is not rising damp.
The cavity insulation could be the trouble with the lower damp, it will dry out eventually and the damp level should literally fall down towards the ground. If the inside is dry I would just give it more time.
Another potential problem is that when the old window was taken out and the aperture bricked up, too much junk fell into the bottom of the cavity and has bridged the DPC. What happened with the cavity insulation when the window was removed?
Frank

 

[stuart45]

What is an FFL ?

Can be a number of things (Fantasy Football league etc), but in your case I think Vinn means finished floor level.

 

[trevorbayliss]

How do you fix those damp spots though ? Can i drill out the mortar at some points and insert those plastic weep holes. They sit between the bricks.

The arch doesn't stick out.

The window was an old wooden one with a top opener. Pretty standard. I bricked it up. It is possible mortar has fallen down the bottom, but i think the insulation already in the wall did stop a lot.

I am just not sure if the wall was damp before i did the work. The house was pretty knackered and i have renovated it pretty thoroughly.

FFL is one or two bricks above the top of the air vent.

Thanks for the feedback.

 

[vinn]

Go out in the rain and look for a pattern. Notice how the water runs down the surface or the pipe.

The "weep hole" notion wont work.

One possibility would be to open up the wall to expose the cavity insulation, & any possible cavity bridging at the DPC level of the cavity.

Speculation only:
Moisture can penetrate an outer skin of brickwork and dribble down the cavity face until it hits a snot on a tie then it can cross the cavity to the interior skin.
Moisture penetrating a wall could saturate from the inside of the skin to the outside after soaking any squeeze or snots.

Have you been under the floor and examined any joist ends in that wall?

When you re-pointed how deep did you rake out?
Has any waterproofing liquid been applied to that brickwork?

 

[trevorbayliss]

Not examined the joists and i have a new floor covering down with plywood now, so not possible for me to do that.

I used a grinding disc to cut into the mortar. Just the small disc.

No waterproofing liquid has been used.

 

[trevorbayliss]

Thought i would bump this thread back to life as i have an issue inside the house now. There is a damp spot on the internal wall. Similar place to where this window was bricked up, but at the bottom of the wall.

I am thinking mortar has gotten in and bridged the cavity, so i may need to look at taking out all that new brick work and redoing it again after cleaning out the channel.

I also placed loft insulation in the cavity when i did the wall thinking this would be ok insulation. I am wondering if this is now just very wet.

Would you try installing a DPC on the external brickwork first ? I have a tube of dry zone so it is pretty straight forward.

 

[KenGMac]

trevorbayliss, good evening.

I am deeply suspicious of the Cavity Fill?
What happens is that rain water saturates the external leaf during winter this rain continues, the external leaf becomes saturated, without the assistance loosing water into the cavity the water can only evaporate to the external, as for the Cavity? if it is full of Insulation? it is obvious that the old Insulation slowly also becomes Saturated.

Where does this Moisture held in the Cavity Fill go? is slowly starts to saturate the inner leaf.

The result? spots of dampness appear in random areas on the internal plaster.

I have seen insurance claims where the entire gable, ground, and first floors over the entire width of the property where the Plaster was saturated, the wall paper was falling off as indeed were the wall tiles? [nasty]

For my sins I have also been involves with Insurance Claims where the Householder mad a [successful] claim against the installer and more importantly the "Guarantor" of the work to install this grossly defective Cavity Fill. Result was that the guarantor paid to have the defective Cavity Fill removed, paid to have the internal surfaces of the Cavity dried, paid to make good the plaster and paid to re-decorate several rooms completely.

There is a small but thriving area of the insurance industry, but kept possibly intentionally quiet?

Ken.

 

[trevorbayliss]

I have heard of issues with cavity fill, but not experienced many problems before. This house has the cavity fibre fill, but the issue is based around this window which i have blocked up. I am pretty sure it is my own doing which has caused this localised issue.

The extra cavity fill which i used was the soft loft insulation stuff. Should have used kingpin stuff really, but it was just for the small area of this window.

Before i take out all the bricks i thought i would repost and see if any more info out there to guide me. Not going to do any work until spring however.

 

[stuart45]

You shouldn't use loft insulation for cavity fill as the fibres are different to cavity batts and will allow water to pass through to the inner skin.

 

[trevorbayliss]

ok so this maybe my problem - duh!!