DAmp

[shreds]

Hi, I hope someone can help. We have a breather pipe boxed in in the corner of our downstairs bedroom. The toilet is directly above the bedroom and breather heads up through roof.

A damp patch has developed where the box for the breather meets the stone wall (terraced house) and the floor.

Is a roof leak following the breather pipe more likely than rising damp ? (ive examined all the connections in the bathroom and can't see any evidence of leaking here so thinking it is unlikely to be integrity of pipes). Is rising damp much less likely due to the house being terraced?

Any suggestions on how to begin to tackle this would be much appreciated.

Thanks in advance
Dave

[tim'll fix it]

you wont get rising damp above about 1m due to air pressure

[nonmember]

Need more info

1. Flat or appex roof
2. Is the actual wc directly below the box
3. What goes into the 4" stack
4. Is the damp adj to a external wall

[shreds]

Cheers for the help.

Answers to qs below. by way of update have replaced a secion of plaster board where damp appeared. noticed a damp patch on the outside of new plasterboard a couple of days later and removing it showed there was moisture on the bedroom side of the board. No sign of water on waste pipe or the rear of the board.

However did notice that there was no apparent cavity insulation and that there was a cool draft between the plasterboard and the outer wall. Would i be right in thinking that it is most likely to be an insulation issue and damp would be caused by condensation???

Cheers
Dave

1. Flat or appex roof -
Roof is apex

2. Is the actual wc directly below the box -
wc is above bedroom, waste pip runs down same corner where damp appeared

3. What goes into the 4" stack -
4" stack?

4. Is the damp adj to a external wall
yes although significant gap between plasterboard and brick as mentioned above