Prevent dry rot from spreading

Question

Last winter, I had serious dry and wet rot issues in the basement. The reason seemed to be that the wall was not watertight. This has been corrected and repair works were carried out by professionals (changing the ceiling of the basement/floor of the ground level and finishings).

A few months later, it seems dry rot is coming back:

I'd like to prevent it from spreading, and I see three possibilities, but need help to make up my mind:

• Installing a fan to take air from the basement outside; can take moisture out, but I'm afraid it only removes the air which is the center of the room, not the air close to the dry-rot.
• Installing a heater in the basement, but I'm afraid the heat helps the rot spreading out.
• Installing a dehumidifier with a pump, but it's hard to reach a outlet pipe because there is no basement under the kitchen.

I have read quite a lot about this but professionals do not seem to agree on the solutions. What solution would you recommend? At this point, getting rid of the mold matters more than the cost.

This is the average temperature/rain in the location of the property, which is in the UK a few miles away from the sea:

Answer 1

I'm writing this answer based on the assumption that you are using the words dry/wet rot and mold all to mean just mold. Mold needs three things to grow, moisture, darkness, and warmth. Since moisture causes other problems besides just mold I generally recommend mitigating the source of moisture, but if that is not feasible then adding UV exposure will prevent surface growth.

Answer 2

Since all the wood and carpet are removed the spores must be in the walls. One way to really knock down this kind of growth is hydrogen peroxide a 3% solution with water will kill it and keep it from growing. Once the walls are washed down with 3% hydrogen peroxide keeping the moisture down with a dehumidifier will be the best way to reduce further growth. Once the spores are in the walls it is almost impossible to completely eliminate it without a dehumidifier and regular wash downs of the problem areas. I get my peroxide at a chemical supply store I think it is 30% and it is verrrry strong, safety warning it must be diluted if you get it on bare skin it turns your skin to a white mush and you add the peroxide to water don't add the water to the peroxide or you chance a thermal event (small explosions). The one good thing about this over bleach is it doesn't stink up the house, but it will take the color out of clothes and hair at stronger solutions.