Pointing - Has the correct mortar been used

[Anthony Duffey]

Hi guys

I have been doing a bit of research about damp as I seem to have a problem with "rising damp" Please see the photo of the inside of the proprty.

I have researched the different Damp Proof Courses and I was about to purchase some Dryzone damp proof course cream with a view to stop the damp problem. However I came across an article about "rising damp" and how it dosn't really exist and that other factors could be causing the damp problem.

When I had a look back over the wall to factors looked like they could have been possibly causing the problem:

• The pointing
• Concrete/ mortar upstand at the bottom of the wall

I have had a look at the pointing and I think it may have been re pointed using cement and not lime mortar. I have picked a bit of the pointing away and taken a photo which I have attached. I would like to know where I can send a sample of the mortar off to for testing if possible? I feel that the water could be getting trapped inside the wall by the cement pointing as the lime mortar beneath is unable to breath. Generally speaking the pointing and brickwork is in good condition (please see the photo). I am not sure when it was completed but this was done before I purchased the property about 5 years ago.

There is a also an upstand against the bottom of the outside wall. Could this be contributing to the damp problem by trapping the moisture in? Please see the photo.

Any advice would be greatly appreciated.

Thank you in advance

 

[vinn]

Are the walls solid?
Are any floors solid? suspended? I dont see any air bricks.
Where's the DPC in the photos?
White efflorescent salts can be seen on your pointing and plinth.
The pointing seems to be sand & cement - with very little cement in the mix (not a bad thing).
Besides the penetrating damp signs in the alcove photo, are there any other signs of damp in the house, at skirting level esp?

The S&C plinth needs removing from around the property - there's a colour change in the bricks just above the plinth.
The bricks are a soft red brick - I think local names are used for this type of brick? Its a porous brick, it will absorb water.
Looks like someone has attempted a French drain, & patched the plinth - indicating previous damp
difficulties.

 

[Doggit]

I think it looks more like dirt than a French drain, and the plinth looks cracked and open at the top. I don't think you have a problem with the pointing, but the plinth may well have been put in to stop water pooling at the wall, so you'd need to take the plinth off, and then dig about 6" of the concrete out to a depth of about a foot or so down to the earth, and use at least 20mm stones to fill the trench.

 

[John D v2.0]

You don't need to get it tested, just dump a bit in some vinegar and it'll fiz if it's lime.
We have a combination on our house, the area of brickwork at the front was originally bedded in lime and pointed with cement. It had been painted since, and water had got behind it all and dissolved the lime in places. The bricks are extremely soft and absorbent. Some of the bricks even dropped out, literally, when I removed the cement.
I basically smashed all the cement off, repointed in nhl3.5, which looked lovely. Then we painted it all with black masonry paint in the end!

The important thing with solid walls is you have to get the balance of drying out and getting wet right. And make sure the mortar is softer than the bricks, then it won't trap too much moisture in there.

 

[Anthony Duffey]

Thanks for the feedback guys

Vinn

Are the walls solid? It is a cavity wall
Are any floors solid? suspended? I dont see any air bricks. The floors are timber and there is a basement beneath. There are a few air bricks but the two next to each other are blocked by the looks of things
Where's the DPC in the photos? I am not sure where the DPC is. I can try and dig a bit of the mortar away to see if I can see it.
White efflorescent salts can be seen on your pointing and plinth.- I am not sure what this means.
The pointing seems to be sand & cement - with very little cement in the mix (not a bad thing). - Do you think I need to take this off and repoint in lime mortar? It would be a big job to do the full wall as access to get to the top would be very difficult due to the narrow passage way. I could always rake out and repoint 1 meter high to allow the bottom of the wall to breath
Besides the penetrating damp signs in the alcove photo, are there any other signs of damp in the house, at skirting level esp? There are. In the front room the wall feels a little damp

There is no French drain in place at the moment but it looks like this might be a good idea and somthing I hadn't thought to do. I think I will also have to remove the plinth too.

Thank you for your help


Doggit

I think I will remove the plinth as you have suggested.

When you say install a French drain does that mean including a pipe to remove the water or will just digging out the concrete to a foot in depth and filling it with 20mm stones be ok?

John D

I have done what you said in order to try and confirm for sure if it is cement or lime mortar. I put some of the new mortar that was used for repointing in one glass and some lime mortar in another. To be honest they both fizzed with the lime mortar fizzing a bit more. If it is cement mortar do you think I should rake it our and repoint?

 

[Doggit]

As long as you've got down to earth so the water can drain into it, then you don't need a pipe to take away the water. But as you've got the air bricks above the ground level, that suggests that the ground level is well below the DPC, so although the plinth looks iffy, I suspect you need to take up the floorboards inside the house, and look for any problems under there.

Do you keep your windows open or closed, is there a build up of moisture in the house that's then settling into the walls.

 

[vinn]

OP,
Has cavity insulation ever been installed? How do you know that its a cavity wall?

Just clean the a/bricks out or blow them out. You really need cross ventilation through the cellar(s)?
From below in the cellar(s) check your joist tails for fungal damage - they will be sitting in wall pockets or on a ledge.

Rake a little out and show the position of the DPC on a photo please.

Salts indicate excess moisture in the bricks & mortar.

Your pointing might be a mix of S & C & a little lime. If you dont have CWI then having a look inside the cavity would be very useful for you -

Except for what I've suggested so far dont do anything else until the cause(s) becomes more clear.

The down pipe discharging on to the concrete should be diverted somewhere else. Can you post a photo of the gable wall and passageway?

I take it that all the damp signs are on this gable wall interior?

Was any furniture positioned close to the damp areas eg. in the alcove? Close enough to allow condensation? Can you post a photo of the front room damp?

 

[Anthony Duffey]

Thanks for all your help guys

Here is an update:

Doggit

Do you keep your windows open or closed. Genrally speaking the windows stay closed. I live in the town centre and there can be times where there are alot of break ins unfortunately.

Vinn

I have taken a few more photos which I have attached.

Has cavity insulation ever been installed? How do you know that its a cavity wall? Cavity insulation hasn't been installed. I know it is a cavity wall because I removed a brick at the end of the wall so I could run a pole along the cavity to rake out any dirt blocking it. This was a few years back.

From below in the cellar(s) check your joist tails for fungal damage - they will be sitting in wall pockets or on a ledge. I have been into the cellar to check the tails and they seem to be dry (please see the photos). The front of the chimney brest is very damp. The render has started to come away from the wall as a result. In the alcove on the other side (above is the en suite bathroom) of the chimney it also seems a little damp but not as much as the other side (above is the warderobe).

Rake a little out and show the position of the DPC on a photo please. I have done this but I can't find the DPC (please see the photos). I raked out just above the plinth an the other two courses above. I read that some older properties use engineering bricks but I am not sure what they look like to tell if they are in place.

The down pipe discharging on to the concrete should be diverted somewhere else. Can you post a photo of the gable wall and passageway? I will make sure the pipe discharges into the drain opposite. I have added a photo of the passageway and gable wall. Thanks.

I take it that all the damp signs are on this gable wall interior? Most of the damp appears to be on this gable wall. The property is semi detached. There is a little bit on the back wall too but I think that may be from the plastics around the uPVC window. I am going to take them of and re silicone them up. The alcove at the other side of the chimney breast is an en suite bathroom. There is a little bit of damp showing in the corner just above the tiles (please see the photo)

Was any furniture positioned close to the damp areas eg. in the alcove? Close enough to allow condensation? Can you post a photo of the front room damp? In the bedroom that I have previously showed you there is a wardrobe in the alcove I have removed it a took a photo. There is also a desk at the front of the fire place (please see the photo). Both walls are a cold at the bottom and a little bit damp. I have ran my hand along the wall and it seems a little rough like it could be salt.

Thanks for all your help.

 

[Doggit]

If you're windows are kept shut, and there's furniture covering the damp areas, then the problems more likely to be high internal moisture levels with the moisture settling out on the cold surfaces. You need to keep a good airflow through the house to get rid of the moisture from everyday living. If you've got noise problems from the road, then you may have to look at installing a whole house ventilation system.

But at the same time, it looks as though some remedial work has been done to the joists. They're fairly new, and blue plastic has been used as a dpc under the joists

 

[vinn]

Remedial timber work has taken place in the past - have the joists, or a joist, been notched onto a plate? Was your cavity clear above the level of the outside passageway? I ask because I'm wondering how the joist tails became damp before the remedial work?

Hold fire with any digging or French drain(s) - It might make matters worse.

The DPC is possibly buried behind the plinth.

The chimney btreast and its flue(s) - are the fireplaces open or blocked - if blocked have vents been installed?
Some of your difficulties might be caused by unventilated & unswept flue(s)? Chemicals can leak through the c/breast brickwork & contaminate the decorated surface attracting condensation damp.
So it would be wise to vent and sweep all flues.

However, I think that you mainly have condensation difficulties - the bathroom & the bedroom are too high for rising damp & the cavity is a barrier to penetrating damp.
Try 24/7 trickle heat and constant ventilation, with furniture to be pulled away from all exterior walls, & see how it goes until Jan/17?

FWIW: its good to have powerful extractor fans in the kitchen and bathrooms.