Wall cracks

[dave70]

I'm after some advice (and hopefully reassurance). I know it's difficult to assess cracks based on descriptions, but I've not got a photo to hand. Sorry about the length of the post!

I have a 1890s end terrace. There is a plaster crack running diagnoally up across an upstairs wall, towards the corner of the wall, and the back down an adjacent wall. It starts where some frame work for a retrofitted stairwell into the attic conversion is fixed to the wall.

The wall in question is not plasterboard, but I couldn't say if it was lath and plaster or if the lath had been removed and the bare wall plastered at some point.

The crack is probably only about 1 mm thick, maybe 2mm max and is largely the same thickness throughout.

The area around the crack sounds hollow when tapped, the rest of the wall sounds solid. The plaster immediately surrounding the crack flexes when you push on it, closing the crack up a bit.

Obviously I'm aware that cracks in old houses are part of the course, and I would normally just put this down as delamination of the plaster rather than anything structural but my worries are that it is diagnonal and that it spans 2 walls. We don't have any signs of structural movement - no sticking windows, and no cracks that I can see on the external walls.

Any thoughts would be welcome. I'll try and add some photos when I get a chance.

Thanks

 

[malcolm]

Photos would be useful as there isn't enough info. Cracks are interesting though - it's not how wide they are but how fast they are getting wider that is important.

A 2mm crack wouldn't worry me if it started in 1850, but it's a good size of crack to appear in a recently decorated wall.

 

[dave70]

I've attached a picture of said crack. I've yet to measure the thickness, but on looking at it again, I'd say it was probably less than 1mm. Also to note, the area around the worst part of the crack as well as sounding hollow, is bowing outwards slightly.

 

[Cubist]

All houses move a little during the course of a day as a consequence of heating and cooling - internally and externally. Also, some materials will expand and contract at different rates to produce differential movement that, in the very worst cases, can be very damaging. In your case the cracks seen in your plaster are completely normal and easily repaired. That said, when it comes to the section that appears to be 'bowing' its most likely that this is due to some separation between the various plaster coats or perhaps separation of the lath/plasterboard from the underlying lintel/brickwork. A little probing with a sharp pointy instrument may be the best way to proceed.

 

[a twig]

I’d agree, not a crack to worry about in my opinion

 

[Stevers]

Nothing to worry about if that plaster has been there for any length of time. Also why our ancestors invented wallpaper, and we use the expression 'paper over the cracks'!

 

[mattyb]

I'm no expert in this area, but have had similar on a couple of properties.

Personally I would say these don't look too concerning. Properties move a bit (especially period properties). Issues with subsidence will usually result in vertical cracks (although they aren't always subsidence). Typically, horizontal cracks are the result of settlement/natural movement.

 

[Stevers]

My parent's home was built in 1934 and has a lot of essentially vertical cracks, and one small area with diagonal cracks. The vertical cracks are due to a lack of horizontal restraint at first floor level requiring stitching of the cracks with helical bar, plus some horizontal restraints need to be fitted through the wall into the first three joists at first floor level where they run parallel to the outside walls. The diagonal cracks are due to settlement under one end of a beam. With what can only be termed a lapsed degree in civil engineering, I diagnosed all this myself, but it has since been confirmed by a chartered structural engineer.

 

[RBailey]

The area around the crack sounds hollow when tapped, the rest of the wall sounds solid. The plaster immediately surrounding the crack flexes when you push on it, closing the crack up a bit.

As Cubist has mentioned sounds like may just be detached plaster.

If your walls have been gypsum plastered or skimmed then this is much harder and will be much more liable to crack (and detach) so you may just have a plaster crack.

Cheers,
Richard B.

 

[mattyb]

My parent's home was built in 1934 and has a lot of essentially vertical cracks, and one small area with diagonal cracks. The vertical cracks are due to a lack of horizontal restraint at first floor level requiring stitching of the cracks with helical bar, plus some horizontal restraints need to be fitted through the wall into the first three joists at first floor level where they run parallel to the outside walls. The diagonal cracks are due to settlement under one end of a beam. With what can only be termed a lapsed degree in civil engineering, I diagnosed all this myself, but it has since been confirmed by a chartered structural engineer.

Great points.

A surveyor friend just said as a ROT that horizontal cracks typically are fine, vertical should be checked by a specialist. But also that any cracks that you can slide a £1 coin in should also be checked.