Damp cellar - more ventilation using a fan/humidstat system

Bigphil1474

Hodd, we just had a sump pump fitted to remove the nuisance water. Cost £2k + VAT. The floor is slowly drying out, but we did have 9 inch of water down there for a long while. If the damp is caused by water under the cellar, then it may be an option. The pump goes down about half a meter, so my plan is to let it dry out slowly, then just lay some screed or concrete over the rest of the floor, paint the walls etc. then shut the door until we sell up. 

hodd

Bigphil1474 said:

Hodd, we just had a sump pump fitted to remove the nuisance water. Cost £2k + VAT. The floor is slowly drying out, but we did have 9 inch of water down there for a long while. If the damp is caused by water under the cellar, then it may be an option. The pump goes down about half a meter, so my plan is to let it dry out slowly, then just lay some screed or concrete over the rest of the floor, paint the walls etc. then shut the door until we sell up. 

Thanks Phil, I've never had pooling of water down there, just general damp. Just thinkin aloud, is the pump a permanent fixture? What if you didnt then lay concrete over the top?

I'm asking because my celar ceiling is quite low, around six foot, and one of the quotes proposed a membrame with a sump/drain and a concrete floor. Due to the limited height, the old flooring would be removed. This is a sizeable amount of work due to getting the debris out and into a skip. The total price was £17000. The value of the house doesn't really justify that amount which would make the cellar only a bit drier than it is now with the portable dehumidifier.

hodd

Advocado said:

The drier you make the air with a dehumidifier, the more moisture will move from the bricks into the air and therefore more moisture will wick into the bricks from the surrounding ground.

Without tanking it and stopping the moisture moving from the ground -> bricks -> air in cellar, the best thing is to just allow air flow.

But it'll never be suitable for storage of perishable items.  As you put stuff in there it'll prevent air flow to certain areas and so damp/mould will occur.

Oh yes, it's slightly nonsensical to use the dehumidifer as it adds to the problem as you say, but it does allow the cellar to be usable and protects the floorboards overead.

That latter point is my main concern. I'd like to rent out the property in future and want to reduce cellar dampness causing problems above.

There are a couple of vertical metal grates built into the brickwork, around maybe 8 x 8 inches. They made little difference judging by the dampness when I moved in. It's a semi detached house, so such ventilation could only be on three walls. Difficult to answer, but how many vents/grates are we talking about to create adequate airflow through? There is also a coal chute covered by a manhole cover. That cover's horizontal but could be made into a grate.

Eldi_Dos

If you are using a dehumidifier with two eight inch grates open to the outside that could explain why you are getting 25 litres of water per week.If you could get a smoking taper to see how your airflow is in the cellar that would help you see where improvements can be made.The coal chute is good news I would look into ways of utilising that

Bigphil1474

hodd said:

Bigphil1474 said:

Hodd, we just had a sump pump fitted to remove the nuisance water. Cost £2k + VAT. The floor is slowly drying out, but we did have 9 inch of water down there for a long while. If the damp is caused by water under the cellar, then it may be an option. The pump goes down about half a meter, so my plan is to let it dry out slowly, then just lay some screed or concrete over the rest of the floor, paint the walls etc. then shut the door until we sell up. 

Thanks Phil, I've never had pooling of water down there, just general damp. Just thinkin aloud, is the pump a permanent fixture? What if you didnt then lay concrete over the top?

I'm asking because my celar ceiling is quite low, around six foot, and one of the quotes proposed a membrame with a sump/drain and a concrete floor. Due to the limited height, the old flooring would be removed. This is a sizeable amount of work due to getting the debris out and into a skip. The total price was £17000. The value of the house doesn't really justify that amount which would make the cellar only a bit drier than it is now with the portable dehumidifier.

Hodd, yes the sump pump is a permanent fixture. Hard wired in with piping to external drain. It's fitted into a plastic casing with a manhole cover over it. 
I was only thinking of trying to smooth the floor over rather than lay a lot of concrete on.  I have about 6 feet clearance, so can't lose much. The original floor is concrete but it has deteriorated a bit in places. Looks like some sort of plastic was laid under it as it is showing here and there. Just going to clean up the floor everywhere, apart from where the pump is. . I was told that the floor surface won't get wet as the sump will remove any water coming up before it gets to the surface, so in my head that means I can smooth the floor out and it'll be fine. 
I don't know if a sump pump will help you, depends on the source of the dampness. From the sounds of it, your cellar is like mine was before the great flood arrived - and for me an extraction fan was enough to keep it under control, which I suppose is just about getting air moving round the room.

hodd

Eldi_Dos said:

If you are using a dehumidifier with two eight inch grates open to the outside that could explain why you are getting 25 litres of water per week.If you could get a smoking taper to see how your airflow is in the cellar that would help you see where improvements can be made.The coal chute is good news I would look into ways of utilising that

I should have said I stuffed some rags into the grate openings to block them and let the dehumidifer do its work. I'm pretty confident that 25 litres from the floor and not the outside air

If I go with the airflow option, I'd obviously remove said rags.

The coal chute is interesting as when I moved in, the manhole cover was just placed on top. Although it's heavy and in a frame, anyone could have lifted it up and gained access to the cellar. I drilled holes in the cover and frame and bolted it in place. That was no small job! If all else fails and I have to get the cellar redone, e.g. with a membrame/sump, the coal chute would probably be enlarged to allow better access during the work. 

hodd

Bigphil1474 said:

hodd said:

Bigphil1474 said:

Hodd, we just had a sump pump fitted to remove the nuisance water. Cost £2k + VAT. The floor is slowly drying out, but we did have 9 inch of water down there for a long while. If the damp is caused by water under the cellar, then it may be an option. The pump goes down about half a meter, so my plan is to let it dry out slowly, then just lay some screed or concrete over the rest of the floor, paint the walls etc. then shut the door until we sell up. 

Thanks Phil, I've never had pooling of water down there, just general damp. Just thinkin aloud, is the pump a permanent fixture? What if you didnt then lay concrete over the top?

I'm asking because my celar ceiling is quite low, around six foot, and one of the quotes proposed a membrame with a sump/drain and a concrete floor. Due to the limited height, the old flooring would be removed. This is a sizeable amount of work due to getting the debris out and into a skip. The total price was £17000. The value of the house doesn't really justify that amount which would make the cellar only a bit drier than it is now with the portable dehumidifier.

. From the sounds of it, your cellar is like mine was before the great flood arrived - and for me an extraction fan was enough to keep it under control, which I suppose is just about getting air moving round the room.

I'm 71m above sea level, I don't know if that means I'm immune to flooding but the survey said a flood would be a once in a lifetime event. The water comes from rainwater in the soil. 

Can I ask who/which sort of company you contacted for this work, please? I'm struggling as most companies offer just tanking or full conversions. I'm looking in the wrong place.

JD_29

Hi Hodd. In a virtually identical situation to you, seeking clarity on this. Did you manage to get any specific product suggestions? Did you get the problem sorted?