Self build Rising Damp 1930s house

Diyselfbuilder

I have bought a 1930s built semi d house. The walls have rising damp, mostly at the side entrance. The ground level in the side entrance was at the same floor level. I have dug the side entrance down about 1.5 foot.

The house slab has no damp proofing. I know it's best to remove the concrete slab and put in dpm but not something I want to start. Would it make a difference to remove the slab all the way around the house at the inside wall and put down dpm there ? How can I rectify the rising damp in the walls? Would lowering the outside ground level sort this ? Maybe adding eco drains at the side entrance ?

This is just one room on the gable end. I had to dig up for a sewer pipe here. The slab is only about 4 inches thick. You can see the old paint flaking off from rising damp. The walls are not block work, they are poured concrete.

GreeBo

I would first make 100% sure its actually rising damp as most of the time it isn't, its something like a dodgy gutter outside, or something piled up against the wall outside.

Is the floor itself wet or is it just the walls?

Furze99

Rising damp is not as great an issue I think, as the companies selling solutions for would have you believe. That said, I think mass concrete walls might be more prone to it. One approach is to drill holes at regular intervals and a solution is pumped in which is supposed to reduce absorption of water, there are specialist companies for this. Rented a house with these mass concrete walls once and it was the coldest place I ever lived, like a fridge in winter! So research all the possible insulation solutions..

GreeBo

Whats on the exterior walls? If its just cement render then this can hold in the water, you might see great benefits by just waterproofing this layer (even painting it can work, but I would go chemical first)

At this time of year solid walls are prone to condensation, so before I went to any great effort I would get this determined.

Diyselfbuilder

When I first entered the house, the walls and floors were damp. I pulled up the years old laminate vinyl and the floors concrete floors were mouldy and damp. The skirting in the house ground floor are all concrete and I can only guess this is because of the dampness and timber would be destroyed quickly.

The render is concrete and I will definitely take your advice on board to seal it or paint.

I am also thinking I should use dryzone rods on all external walls as there's no dpm anywhere.

I am worried that the damp could be coming from the damp soil under the concrete slab. After removing some slab for the sewer pipe in an area, the soil under the slab is quite damp.

SchrodingersCat

Skill builder did a good video on combating rising damp.

https://www.youtube.com/watch?v=irytqcJZSps

However, as others had said, I have read that it is more commonly caused by other sources of water like guttering, leaking pipework, etc. Could there be nearby pipes, gullys or drains?

GreeBo

https://www.boards.ie/discussion/comment/119988954#Comment_119988954

I'd check for a leak so, as it would be strange for an empty house to have that much damp in the flooring without a broken or cracked waste/soil/drain pipe somewhere. There is no reason for the soil under the house to be damp unless you have a leak, poor grading towards the house or a stream etc nearby?

Under the house should be bone dry since the house shelters it from rain.

The Continental Op

My guess is thats just dripping damp what you get in cold houses when cold damp air hits even colder walls.

Insulate on the outside and spend some money heating it on the inside.

GreeBo

I would dig a small trench around the outside, maybe a foot down by a spade across and see if it fills up with water.

It can form the start of a French drain if needs be, so wont be wasted effort.

10-10-20

https://www.boards.ie/discussion/comment/119990166#Comment_119990166

It can form the start of a French drain if needs be, so wont be wasted effort.

...and can be the 600mm of EWI down to the foundations too. Double-bonus!