Painting above and below (over) damp course on internal walls?

Hi

I have a 1930′s house which still retains a number of kitchen ‘extension’ rooms, such as a larder/pantry and boiler house. I am currently decorating them to clean them up.

The rooms have some exposed brickwork and concrete so I am also looking to paint them to seal and reduce dust and dirt. In doing so, I have uncovered some minimal damp and I want to be sure that I’m not causing more and still allowing the rooms to breathe.

The house has a normal damp-proof course (DPC), air bricks, some concrete floors, but mainly standard suspended wooden floors.

My query is regarding the pantry and the boiler house which both have floors at ground level i.e. below the DPC and the best course of action for decorating them without encouraging damp.

Under Stairs Pantry….
The pantry is plastered to floor/ground level on the inside of the external wall and the wall which borders the concrete/quarry tiled kitchen. It is the original plaster. However, some has blown on both walls mainly below the DPC. Part of the external wall is papered in vinyl wallpaper which has peeled in places and did have some mould spots on it. I have washed it off as there was a damp smell and will be replacing the removed plaster in the Spring. Also on the outside wall there is an freely open air brick below the damp course level.

(Also of note is that the exterior walls are cavity walls but that they have been insulated with foam as has been fashionable over the last 20 years or so and this I understand can cause damp penetration issues.)

The other walls border on the hall, here there are exposed bricks (not plastered) and you can clearly see the damp proof course and then there’s another row of bricks above and then the edge of the hall oak parquet floor which is level with the rest of the main ground floor of the house.

My question is.. is there any harm painting the bricks above AND below and thus ACROSS the DPC?

I don’t want to cause more problems by bridging the DPC even with paint (even though the outer walls were clearly plastered from new and it does bridge the DPC). The bricks were already painted with matt emulsion, but I have been painting them the last couple of days with some exterior masonry paint. I am now questioning myself as I imagine this is an acrylic PVC formula which does not breathe as ordinary emulsion.

Obviously, if the parquet floor is suspended then the bricks would receive airflow from the other side, so that could be OK. Are parquet floors all suspended?

I am wondering if I should attempt to break the membrane that I have now created which bridges the DPC though? Or doesn’t it matter? I am assuming that the paint will flake slightly anyway below the DPC over time? But then I’ve only know this to happen with normal emulsion not acrylic masonry paint.

The boiler house…
This is completely unplastered… just bare brick, currently painted with ordinary emulsion. Again the floor is concrete and at ground below DPC level. I presume I am better to definitely stick with normal emulsion for this room? And whatever advice I receive for the treatment of the DPC painting from the pantry will also apply here.

I’d be really grateful for advice as I was about to embark on the concrete floor paint over the next couple of days in the pantry and will then unable to try to scrape any paint off on the DPC for days!

With many thanks in advance for your advice!