• Damp issue, cause known
• Small isolated area

Customer description

There is a dampness issue in the living room of the house we have just purchased. We complete the purchase on June 24th, so we are looking for someone available as soon as possible after this date.

Here is the description and recommendation from our building surveyor:

The dampness here extends 1.5m up the wall and continues around into the north-west corner of the living room. The plaster has crumbled, there is salt efflorescence leaching through the surface, and high damp readings were returned when the surface was tested.

we believe the fault here is caused by leaks from the rainwater guttering exacerbated by internal condensation. A leak with the guttering will result in rainwater soaking the brickwork and passing through to the interior.

业主对这一错误很坦诚，并表示在潮湿的天气里可以听到雨水打在煤气表箱上的声音。然而，严重的长期渗漏会导致客厅的潮湿，通常会导致砖和铺路的外表面出现绿色染色。有一种轻微的绿色，尽管这并不像我们预期的那样明显，考虑到内部发现。因此我们考虑冷凝。潮湿的墙比干燥的墙冷。因此，温暖潮湿的空气很容易在“潮湿”的墙壁表面凝结，使湿气加重。这是一个重要因素。

Due to the position of large furniture there is also a lack of air movement within the corner of the room. The gas pipe passes from the exterior into the room at this point. The pipe acts as a ‘cold bridge’. Internally, this means that the area around the pipe will always be a cold spot and thus more susceptible to condensation.

To correct the fault, we would recommend the following:-

• Repair, or ideally replace, the rainwater guttering. • Externally, repoint the base brickwork in a sand/lime based mortar mix. • Fill the gap around the top of the bay window. • Inside, remove the damp plaster, exposing the brickwork, and allow the surface to properly dry. This will take some time, though the process can be hastened with the use of a dehumidifier. • Apply a salt neutraliser to the brickwork, repoint in a sand lime mortar and then re-plaster. • The gas pipe should be re-routed so as to pass through the floor. • As above, install a French drain across the base of the wall. • Furniture should not be set against the walls within this area. • As an aside, externally there is some blistered and loose render noted within the entrance porch. The same repairs detailed above apply here too.

We are mindful that long term rainwater seepage can cause rot to develop in sub floor cavities. As part of the repairs detailed above, we would also recommend that the floor frame within this part of the living room is examined and any repairs carried out as necessary. This will require lifting of the carpet and floorboards.