cracked wall reason?

[engine]

hi,

our house is end terraced, and we have a vertical crack near the centre of the gable end running down the internal wall only (no crack on the external). the crack meanders a bit but basically runs vertically.

the wall is wallpapered, and when the house is heated, by the central heating or just on a hot summers day, the crack reduces in width. this shows itself as the wallpaper raising slightly along the crack. when the temperature is cooler in the house, then the previously slightly raised wallpaper sits back and flatens against the wall.

the change in the crack width (shown by the amount of wallpaper raised along the crack, i guess) can happen pretty quickly. for example, with a cold house on a winters day there is no sign, but after just an hour or so of the heating on high the raised wallpaper occurs, and gets more raised as the heat rises.

the blocks on the gable end internal wall are a thermal type, and the external wall (which has no signs of cracking) is brick.

any advice would be greatly appreciated, as i've trawled the net for an answer, but to no real avail.

thanks.

 

[r896neo]

Is your house quite recently built with thermolite blocks or similar? I think they are a little prone to cracking as they suck up moisture so quick and too strong a mix can result in vertical cracks such as you describe but this is just second hand knowledge so don't be concerned until someone more knowledgable comes along.

 

[Nige F]

I concur with that - with pehaps a little more knowlege and a couple of those pesky cracks @ my last house - about 2 feet long, they were.

 

[Static]

Right so you get vertical cracks in blockwork cos of thermal changes.. well could be thermal movement

In theory there should be a movement joint in blockwork over 6m without a return wall.. as the crack meanders then chances are you dont have one..

So how long is the gable wall (internally)?

Also age of property helps

 

[engine]

hi r896neo, nige f, and static. many thanks for your replies.

the length of the internal wall is 7.6 metres, which ties in with 'static's' explanation. there is a block return wall, about halfway along, downstairs but no solid return wall upstairs. the house was built circa 1976, we have lived there since 1987. visibly, the crack runs from ceiling to floor upstairs, whilst downstairs that wall is tiled, so cant see. i'm guessing the width of the crack never gets wider than 1mm and reduces to near zero.

the crack is not new, and has been there as long as i can remember. i previously thought it changed width (not a lot, but prob exagerated by the slight raise in the wallpaper) with the hot and cold seasons, but now realise it changes really quite quickly due to internal temperature alone.

is this serious? and is there a remedy? i wondered if having cavity wall insulation inserted into the gable wall would help in reducing the temperature differential between the internal and external walls, and thereby lessen the movement, but not sure?

again, really appreciate your replies.

all the best + thanks.

 

[Static]

7.6m isnt that far off the basic limits.. was expecting to hear more like 11m or so, then it would pretty much be a sure thing for thermal movement..

It may well be that the house builder put the movement joint on the ground floor only.. normally would hide the joint behind a partition or boxing out area so any movement in the finishes goes pretty much un-noticed..

Its not serious if it is just thermal movement.. and 1mm cracking doesnt sound that bad..

With cracking its best to monitor for a fairly long time to check exactly 100% what the cause is.. normally a good 6-12months should do.. then you can sort with a suitable remedy and not have to redo the plaster every year..