Q. I am worried about some cracks in my house both at the edge of the ceiling and above and below a rear window. What should I do?
HMH. The crack at the edge of the ceiling is most likely a shrinkage crack. The plasterboard ceiling is connected to the timber floor structure above and timber can dry out and shrink marginally. This is common in newly built houses and is of no structural significance (i.e. polyfilla is the answer after the crack has settled).
The wall crack should be monitored and the problem might be due to settlement and this should be looked at, especially if the crack is on the inside as well as the outside.
The window area of a wall is the weakest and will show cracks first. Cracks can be structurally tied and in cases where they are getting worse underpinning of walls or foundations may be required. This involves localised digging and insertion of concrete below ground, not quite a diy job that I’d recommend without a structural engineer.
HMH: Yes. 40 square metres (about 430 sq.ft) but there are certain limitations you also need to be aware of. Any earlier (post 1963 extension) is taken out of this area. The area is an internal wall measurement but if a section of back wall becomes “internal” it’s area also needs to be included. The extension must be single storey except for 12 square metres which can be upstairs in a terraced or semi-detached house or 20 sq.m. for a detached house. This upstairs extension also need to be at least 2 metres from the site boundary. There are other restrictions on upper storey windows. Remember that if your house is a protected structure the above rules may not be assumed as the “character” of the house needs to be considered carefully.