Rising Damp and Plastering

[Ben WW]

So the saga with the project house continues.

Some of the existing internal walls have a small amount of damp in them but this wall is the most notable.. it appears to have been replastered at some point too. (All images are the same wall).

Would the internal walls have had a natural slate damp course as the outer walls do?

I am guessing it'll be an damp proof injection job and replaster?

 

[vinn]

If the outer walls have a slate DPC so should the inner walls. But there's no guarantee until you go under the floor and look at both sides of the wall in the sub-area. Could that wall have ever been an outside wall before some kind of house extension?

What's the condition of the plaster on the other side of the wall? Do you have pics?

You will need to hack off the plaster back to bare brick to a height of about 1200mm - 1000mm. First remove all the wallpaper & the skirtings - examine the back of the skirtings.

Wherever in the house that you see damp signs then the plaster has to come off. If you have damp on internal walls then its often the case that there's damp on external walls.
Where walls are damp then joists are at risk.
Do you have ample air bricks and through ventilation?

The best remedial render mix is 3:1 sand & cement with a remedial skim.

 

[Ben WW]

If the outer walls have a slate DPC so should the inner walls. But there's no guarantee until you go under the floor and look at both sides of the wall in the sub-area. Could that wall have ever been an outside wall before some kind of house extension?

I believe it was an outside wall yes before the extension was put down the side of the house.

What's the condition of the plaster on the other side of the wall? Do you have pics?

It appears to be dry on the other side of the wall. It is bare brick from what I can tell but going to carry out some measuring to ensure there isn't a void I have missed. I will take some pics when at the house tomorrow.

You will need to hack off the plaster back to bare brick to a height of about 1200mm - 1000mm. First remove all the wallpaper & the skirtings - examine the back of the skirting.

I will remove that piece tomorrow and take a look at it.

Wherever in the house that you see damp signs then the plaster has to come off. If you have damp on internal walls then its often the case that there's damp on external walls.
Where walls are damp then joists are at risk.
Do you have ample air bricks and through ventilation?

There are some joists near to one damp area that will need further investigation so I will take the floor boards up to look further.

The front vents have been partial obstructed with a poor render mix which I am in the process of unblocking. Is there a quick way of 'drying out' the under floor void if the wooden subfloor is in good condition still?

The best remedial render mix is 3:1 sand & cement with a remedial skim.

Will further tanking of the walls be required post treatment and before plastering?

Am I right in assuming that DPC will still be needed?

 

[vinn]

It might profit you to post pics of the exterior esp at ground level.

Does the room on the other side have a solid floor?

Its actually easier to crawl under floors, and definitely more productive. But lifting boards and probing joist tails with a small screwdriver will help.

What exactly needs "drying out" - is the soil wet?

Dont tank anything.

Dryzone cream is claimed by some to be a worthwhile retro DPC - I have my doubts about all injected DPC's so research the stuff, and make your own call.

 

[Doggit]

The best remedial render mix is 3:1 sand & cement with a remedial skim

Vinn, would you advocate kiln dried sand, or just building sand, and what about a waterproofer in the mix, or none as you don't recommend tanking.

 

[Ben WW]

It might profit you to post pics of the exterior esp at ground level.

Does the room on the other side have a solid floor?

The room on the other side is indeed a solid floor and as you can just see the floor closest to that wall is solid topped with Minster tiling. I will take some pics of the outside but this is indeed a newer extension (most likely cavity).

Its actually easier to crawl under floors, and definitely more productive. But lifting boards and probing joist tails with a small screwdriver will help.

What exactly needs "drying out" - is the soil wet?

I still haven't had chance to have the floor boards up but I am guessing if there Damp in the walls that line the subfloor that the underneath will be damp/moisture ridden (the blocked ventilation ducts probably don't help)

Dont tank anything.

Dryzone cream is claimed by some to be a worthwhile retro DPC - I have my doubts about all injected DPC's so research the stuff, and make your own call.

I have never heard of the product so will definitely do some research into it.

Thank you so much for your advice Vinn and will make sure I get some more photos over to show more.

 

[Ben WW]

What's the condition of the plaster on the other side of the wall? Do you have pics?

Here's a pic of the other side of that wall. All seems fairly dry to be honest.

Looked into the Dryzone Cream. It looks great stuff by the way, easy install too.

Going to have the flooring up at the weekend and take off the skirting boards in the affected areas so will keep you posted.

 

[vinn]

Is the white wall abutting up to the stair flight wall an outer wall? A pic of the outside elevation might help?
There's no sign of a membrane (DPM) at the edges of the floor?
I thought that the room on the other side was a furnished room with flooring?
Is the internal wall a 9" wall or an 11" wall?
What is the black pipe?

 

[Ben WW]

Is the white wall abutting up to the stair flight wall an outer wall? A pic of the outside elevation might help?
There's no sign of a membrane (DPM) at the edges of the floor?
I thought that the room on the other side was a furnished room with flooring?
Is the internal wall a 9" wall or an 11" wall?
What is the black pipe?

Yes the white wall is the other side of the stair flight. This used to be an outside wall until the 80s at which there was extension added so this is now an interior wall.

The extension does have a visible DPM.

The whole property is solid brick construction (bar the newer extension).

Number 1 is the hall quadrant with the stairwell in the top right.

Number 2 is now the utility where there is a solid floor construction, with a downstairs toilet below this in the bottom left quadrant, again appears to be solid throughout.

There is another room with a suspended floor and an area of damp and we spoke about this at the start (the one I need to get the floorboards up in)

The patch pictured appears to be drying out and was only noticed when we were using a wallpaper steamer in the hallway, creating a lot of moisture in that area. I did however notice some black staining :-/

 

[vinn]

You have damp in the wall & its not due to the steamer.

Why it shows on one side only is possibly due to the painted wall surface blocking any "exit" for the damp, & the damp then finding it easier to exit through the warmer staircase side.

Going under the floor might give more indications of whats happening.

 

[Ben WW]

You have damp in the wall & its not due to the steamer.

Why it shows on one side only is possibly due to the painted wall surface blocking any "exit" for the damp, & the damp then finding it easier to exit through the warmer staircase side.

Going under the floor might give more indications of whats happening.

Cheers Vinn .. a gent as ever.

Makes sense about moving towards the warmer staircase.

All of that area is solid so if I can help having that up it would be great.

Will keep you posted with developments