Damp Advice

[*SMcG*]

Need a bit of advice from you all if possible?

Been in my house for over 10 years and did a side extension in 2016. On the corner of the old external wall (now the middle of the house) there was a little mark looked that like a rusty water mark - we hoped it would dry out after the refurb, but it came back and we've since ignored it really.

This week we moved some furniture against the same old external wall and noticed some bubbled paint and the floor looked and felt slightly damp.

Looking round this room, it seems like another wall on the other side has some blown plaster, so I'm suspecting the worst.

The original house has a void (including this room), and we have engineered wood floor on top of the floorboards. The extended part is solid floor with screed.

It's probably also worth me mentioning that adjacent to the room in question is a downstairs bathroom which isn't really used, other than the loo and sink. The wall/floor area we're noticing the problem with isn't the wall shared with the bathroom. It's the other side a few metres away.

I've attached some pics - any advice on what might be causing it and the best next steps to take would be appreciated!

 

[ree]

OP,
1. You have what appears to be rising damp.
2. You say that there is another wall with blown plaster - is this other wall an outside wall or an inside wall?
3. The wall with the pics - can you pic the other side of that wall?
4. Is the floor on the other side still a suspended floor? Have you been under the suspended floor?
5. Can you post pics of any ground level air bricks on the outside of the house?
6. The rust stain is from a rusting angle bead. A little repair has been attempted at the bottom of the bead area.
7. The skirtings have previously been off the wall - why?
8. Where are the above pics in relation to where the old outside wall was opened up for the extension?
9. Would you know how to sketch a plan view of the ground floor rooms & post it?

 

[*SMcG*]

Thanks for the response.

Let me post the floor plan 1st as it might make the rest make more sense.

The room we're seeing the issues in is the playroom.

The wall I posted photos of is the wall shared with the kitchen/diner.

 

[*SMcG*]

A) location Original photos posted

B) location of blown plaster in utility room. It's an original exterior wall, but it's now internal.

C) other side of original wall

 

[*SMcG*]

8. Where are the above pics in relation to where the old outside wall was opened up for the extension?
9. Would you know how to sketch a plan view of the ground floor rooms & post it?

4) The old house has suspended floor, the extension (entire lower part of plan) is solid floor with screed and UFH.

5) Air bricks on front of house:

7) The skirting was replaced when we did the refurb/extension in 2016. What makes you say it was removed?

8) Hopefully the plan I posted explains this?

 

[ree]

OP,
Thanks for that - the plan does help.
Can you color annotate the plan showing where exactly you have seen suspicious signs?
I had just written the above when I was alerted to your further posts - well done.

You definitely have rising damp.

7. The finished flooring is going under the skirtings.

You will have to remove skirtings in the areas with damp signs.
The plaster will have to be hacked off back to masonry - to as high as necessary plus 300mm. And replaced with 3:1 sand & lime render - dont use any gypsum plaster.
The metal angle beads will have to be cut, and replaced with plastic angle beads.
The other side of the wall skirting will have to come off for examination, & the solid floor membrane (DPM) should then be seen behind the skirting.

Your air bricks might need replacing with, say, SF 13873 76mm x 229mm plastic air bricks set 1500mm c/c, in the front and rear elevations. You must have a thro ventilation from front to rear.
The render should not be in contact with the ground - DPC 's should not be bridged by render or plinths.

There are lots of other damp causing variables but the above will hopefully help.

 

[mrrusty]

You definitely have rising damp.

or maybe not.

It's an old house. Would the original fireplace and chimney breast have been in the vicinity of this problem? Would that room originally have been a kitchen? If it's pre 1930, there would probably have been a cooking range. Would it have been in that room?

 

[JohnD]

OP,
1. You have what appears to be rising damp.

It's a bit surprising to see that old nonsense trotted out.

Where do you suppose the water is coming from? Is your house built over a pond or a spring? Or, much more usual, is water coming from the gutters, drains, leaking pipe or incorrect paving levels outside causing rainwater to collect against the wall?

Until you find the source, you will not repair the problem.

The utility room wet patch looks quite high so is probably coming from above. Stand back and take a wider photo of the entire wall. What's up there? A flat roof? A bathroom? A pipe in the wall? A chimney?

Are the floors concrete, or wood with a ventilated void beneath?

 

[*SMcG*]

Thanks everyone again for your responses. It's really helpful to have some viewpoints to help me get my head around what to do.

The house was build around the 30s or 40s. The fireplace is in another room, but the kitchen may have been in this room or possible more likely in the utility room as per the plan now.

The utility room has a 'new' (2016) pitched roof - there are no pipes or chimneys. There are some pipes in the other corner of the utility room, but I don't think they're the source. Here's a zoomed out view:

I've bought a moisture meter and tested the walls and floors. As you can see, the worst of it seems to be around the entrance to the utility room. Incidentally, the utility is part void and part concrete subfloor.

The moisture is definitely worse closer to the ground on all of the readings so I'd assume that means it's rising??

Although the wall shared with the bathroom looks fine from a reading point of view, we have been able to take the bath apart and there's some very rotten floorboards. The bath hasn't been used for over 6 years, so I suspect this is historical and not a current leak, but we're trying to deal with that now too.

 

[*SMcG*]

So the long and short of it is that I'm going to need some advice from a damp expert I think, but I've read bad stories of people trying to push particular businesses or products. How can I find someone that's truly independent? Any advice appreciated.

 

[mrrusty]

Have a read of this

The Effect Of Salts In Old Buildings. What Damage They Cause

Understand the importance and detrimental effect of salts in old buildings. What makes old masonries crumble and what can be done about it.

www.coreconservation.co.uk

and this

Chimney breast damp and the issues it can cause

Damp patches on chimney breasts that won't dry down? Leaking chimney fixed? We explain these persistent damp patches

www.tracebasementsystems.co.uk

and this

Damp meter

damp meters dont measure damp. used by rics chartered surveyors and pca to prove non existent damp problems. A huge scam.

www.heritage-house.org

It may not be rising or falling damp - it could be the water is coming from the room air caused by salt contamination and the cure is isolation. In addition to the isolation methods described in the articles, I have had great success with plasterboard secured to salt-contaminated walls using foam adhesive.

Here's some "damp patches" that are 6 feet above the corbelled brick footings of this internal wall standing on clay substrate with dust-dry oversite beneath the floor. There is no possibility of leakage from above, and yet damp patches with salt crystals form over where the wet dabs are. The room on the other side of the wall had a coal fire for 120 years (we know- this is my house and it hasn't been sold out of the family since it was built in 1902). Interestingly, another part of the same wall, where the plasterboard is fixed with foam, has no signs of "damp patches" at all. The ONLY explanation is the brick is salt contaminated from combustion products reacting with building materials, and the wet dabs drew salts from the brick which were deposited on the surface when the water in the dabs evaporated.

Every house is different, but in this refurb, we have discovered very high salt contamination, and have been remedying it very succesfully working on the theory of isolating the salts from room air containing water vapour.

 

[*SMcG*]

OK. Consider me educated about moisture meters! But doesn't the fact that the wooden floor is showing as over 16% in parts around the playroom wall (and under 10% pretty much everywhere else) indicate that there's a moisture problem? If we're saying the moisture meter is relatively accurate in wood...?

 

[mrrusty]

OK. Consider me educated about moisture meters! But doesn't the fact that the wooden floor is showing as over 16% in parts around the playroom wall (and under 10% pretty much everywhere else) indicate that there's a moisture problem? If we're saying the moisture meter is relatively accurate in wood...?

There is undoubtedly a moisture problem - the red-rust on the corner bead shows that. The question is "where is it coming from" - it could be "rising damp" (which I think gets blamed far more than it should) condensation (the dew point of "ambient" room air is about 12-13 degrees - and guess what - the bottom of walls is often the coldest area - I can see spots of black mould which to me indicates surface condensation), so any cold spots attract condensation, salt contamination from any of the sources, leaks from below or above....

 

[Nige F]

OP,
I gave you detailed information ref your damp difficulties - I work in the building trades -
.

Jack of all trades, Master of none

 

[Jurassicspark]

Jack of all trades, Master of none

Ah, the jack of all trades.