Vertical crack in integral garage wall

[bobiscuit]

We live in a new-build detached house, construction completed one year ago.

I noticed the other day that the external wall of our integral garage (it's a block wall) has a vertical hairline crack from ceiling to floor, through the mortar AND the blocks.

Is this something to be worried about? I don't especially trust the builders opinion as they're always trying to fob us off, so if it's serious I will probably ask NHBC to get involved.

 

[jeds]

Are they thermal blocks? If so hairline cracks are very common and quite difficult to avoid. Most new houses have cracked thermal blocks but you don't see them due to the plasterboard. A photo would be useful. Not of the crack - of the wider wall.

 

[bobiscuit]

Thanks for that. How would I know if they were thermal blocks? When I drilled into them (on the other side of the garage) I used a masonry drill bit and it still took quite a lot of effort to get in. I've heard thermal blocks are easy to drill into so they're probably not.

I'll try to get a photo tonight.

 

[jeds]

Sounds like medium density blocks. A drill would fly into a thermal block. Cracks are much less common in MD blocks but they do occur. Shrinkage is the most likely cause. A photo of the context would still be useful.