Damp cold spots on plastered walls

[tonyslater76]

Hi all

I have a problem with an outside office that was newly built in Feb this year. When we have cold weather 'cold damp' spots appear on the plaster with salt coming through as well. I have reseacrhed this until I am blue in the face and can not find a fix. My builder has been round to look at it and he put in some airbricks which seem to have got the damp inside under control. This gets worse when it gets colder

any ideas as to what is happening ??

cheers

[/img]

Untitled

• tonyslater76
• 23 Sep 2013
• 1

Untitled

• tonyslater76
• 23 Sep 2013
• 1

Untitled

• tonyslater76
• 23 Sep 2013
• 1

Untitled

• tonyslater76
• 23 Sep 2013
• 1

 

[stevethespreader]

you will get better responses to you post if you can tell us what materials was used in the construction of your office is it single skinned ect brick or block ect was it dot and dabbed ect if it was float and set what materials was used ect ect ect---------

 

[roughcaster]

For a newly built office, that looks an awful mess. If it's that bad now, i'd hate to see it when it gets reallby cold. As Steve said, what is the construction of the walls? and also, what was done to the outside walls? bare brick/block, render, roughcast? I think it'll take far more than air bricks to remedy your problem, if i'm honest. Sorry to have to say that really.

 

[Alastairreid]

Dabbed straight onto single skin brick or blocks by the looks of it.

 

[roughcaster]

Snap!! I would say that too Alastair.

 

[roughcaster]

Are you in Edinburgh now Alastair,, left Ayrshire then, or just working in Edinburgh?
Oh God,,,,,, you're not an MSP now are ya??????

 

[Alastairreid]

Not quite Edinburgh (west lothian) the vast majority of my work is in the lothians and had enough negotiating the M8 on a daily basis.

Still an Ayrshire man 3 out of 7 roughcaster

Hope you are well.

MSP ....whoever designed that parliament building should be shot! along with those in it

 

[tonyslater76]

Sorry for late reply. The building was an old out house. They rendered the outside and plastered the inside. They also put down a damp seal 'Bichmen'? but it seems to get worse when cold.

Hope this helps ?

 

[stevethespreader]

in your post you said the building was newly built now you say its an old out house "which" is most prob single skin which is why your walls are cold and you have cold/damp spots which could be condensation forming on the cold walls, what did they use to plaster the inside with? I think al and rc maybe right by saying d&d and skim because the damp spots look like the shapes of board addy, so was it d&d or plaster? if plaster what did they use? in anycase neither looks ideal for your outhouse, what your builder has also done is try to get rid of the condensation with the air bricks

 

[tonyslater76]

It is an old outhouse that was renovated. It was rendered outside and a new roof was put on. It was plastered inside. the problem was that the builders did a lot of the work when it was cold and snowing ! , this meant that some of the brickwork was still wet when they put the plaster on.

There is no damp in the building now but just these annoying 'cold spots'. Is there any paint I can put over these to cover them ?

 

[JohnD]

so the walls are solid brick, single skin, with no insulation. You have not said what the thickness of the wall is but for a small outhouse I will guess about 4 inches.

So they will be cold.

So if the inside of the room is warm, the moisture in the air will form condensation and damp on the walls. Putting a waterproof coating on the inside of the walls will just cause the condensation to form on the coating.

You say the construction was done in wet weather. The airbricks will be helping because they ventilate out some of the moist warm air.

What did you do to dry out the fabric since build was completed? How do you heat and ventilate it? What activities are carried out in the room?

I wonder if there is a new floor with a DPM. If not, moisture will be rising from the floor as well.

 

[tonyslater76]

Yes thats right about 4 inch thickness of bricks, no insulation.

THere is a new floor with DPM. I use the room as an office so have a computer running and TV screens. I also have an electric heather that I run on low. It all really seems to flare up when colder. I also get a lot of salts coming through on some areas.

 

[JohnD]

you have mentioned heat, but to get water vapour out, you need ventilation. How do you ventilate it dry?

What did you do to dry out the fabric since build was completed?

 

[tonyslater76]

I ran a de-humidifier in there for a bit which seemed to collect quite a bit of moisture but didnt really help the walls. THere are three airbricks in there whcih the builder installed about 1 month ago.

 

[JohnD]

do the windows have trickle vents?

you see, an unisulated 4" brick wall is going to be cold winter and nightime, so unless you have removed the water vapour from the air inside, it is always going to suffer condensation.

If you can clad the exterior, you can incorporate insulation, then you can warm the brickwork. Or you could dry-line the inside with a moisture membrane and insulation to keep the warm moist air away from the bricks.

Heat loss in cold weather is going to be enormous.