Bitumen Coating on cellar walls - Good or Bad?

[applejuice]

Hi,

In my previous house I tidied up my cellar and turned it into a games room, but didn't have enough money to tank it and it didn't really warrant that type of conversion. Therefore I coated the externally facing cellar walls with a bitumen paint before painting with masonry paint. This worked well with the addition of central heating and a de-humidifier.

I have now moved house and have another cellar to turn into my new games room. I was going to do the same thing, but have read articles about letting walls breath and am now slightly confused as to the best approach.

Any guidance on this area would be appeciated.

 

[Lime]

Cellars are at the whim of nature.
Some are wet, some are dry and it is quite common for a cellar to be flooded when next to it in another property the cellar is bone dry.
In clay particularly the drying effect of a drought changes the channels within it so the water can change direction.
A cellar can be wet for years and then suddenly become dry.

Tanking is a short term measure (depending on how much water there is) but eventually the water overtops the tanking or brings water nearer other more vulnerable parts of the house.

The biggest problem of flooding often occur in tanked cellars as the water cannot then get out.

Better to fit an automatic pump in a sump.

 

[NT]

Old cellars are typically not designed to be not-damp, the only 100% proper solution is to line the _outside_ of the walls with a membrane or waterproof layer, but of course this is normally impractical.

Tanking stope evaporation, thus the wall gets wetter. The result is often damp getting through here and there, joist end rot, etc. And where dapm does break through, the ensuing salt deposits are liable to damage the brickwork.

A lime coat allows evaporation, and acts as a sacrificial layer (the surface of brick or lime is damaged by salt deposits). A lime coat wont make the basement perfectly dry, but will avoid the problems above, and RH can be controlled with a humidistatic dehumidifier.


NT

 

[Lime]

Old cellars are typically not designed to be not-damp, the only 100% proper solution is to line the _outside_ of the walls with a membrane or waterproof layer, but of course this is normally impractical.

Tanking stope evaporation, thus the wall gets wetter. The result is often damp getting through here and there, joist end rot, etc. And where dapm does break through, the ensuing salt deposits are liable to damage the brickwork.

A lime coat allows evaporation, and acts as a sacrificial layer (the surface of brick or lime is damaged by salt deposits). A lime coat wont make the basement perfectly dry, but will avoid the problems above, and RH can be controlled with a humidistatic dehumidifier.


NT

Yes, I agree about old cellars being designed to be not-damp.
However the old cellars I have known had always started off in life being well ventilated.
It is only with warmer houses and the reduction of draughts that many normally open access holes (albeit protected by cast iron decorated grills) were enclosed to keep the heat in.
Thus the ventilation of the cellar was stopped up.
All the cellars had lime wash as an original paint except in some coal holes.