Fixing deep cracks into inner wall blocks

[czulu]

12 months ago we had a large steel installed to knock through a kitchen. A large crack appeared in the room directly atop.

The crack hasn't changed or widened since it first occured so my builder assured me its safe (but it's for me to fix) and not a continuing structural issue.

As you can see in the pics I've now taken a closer look and the crack goes deeper than the plaster and you can see/poke right into the block work of the inner wall - maybe 3/4 inches.

My initial thought is to pump some ready mixed mortar repair 'stuff' into the deep block crack, let it cure, then PVA and filler over the top. Is there any reason this isn't a good 'enough' plan?

It's not the most important room in the house, I just need it roughly presentable.

Cheers.

 

[Wayners]

Knock plaster off either side off crack. About 200mm either side.
I've filled cracks like that with bolt resin. That's easy to get in joint.
Other option is sand and cement.
Metal lath over secured with screws with wedi washers.
Plaster over

 

[opps]

I have worked in quite a few houses with similar settlement cracks.

I open up the crack, vacuum it out and brush in dilute PVA to seal the substrate. When the PVA has dried, I fill the crack with Toupret Flex and Fill. It is like a caulk with fibres in it. And like a caulk, it shrinks back as it cures. On very deep fills, I flush fill and leave it for 2 or 3 day to shrink back. I then fill over it with a sandable filler.

It works very well on cracks that are (mostly) settled.

 

[ree]

OP,
Are you saying that the crack immediately appeared after the props were removed?
What are we looking at - where on the wall is the crack? Is the wall an outside wall? Are cracks or disruptions noticeable on the other side of the wall?
Is the floor level - any gaps under the skirtings?

 

[opps]

Is the wall an outside wall?

I would imagine so given that you can see a window sill...

 

[Nige F]

OP,

What are we looking at - where on the wall is the crack?

Under the window sill.....

 

[^woody^]

Walls always move. Always. And you don't really want each side of an internal crack to move differently.

Your proposal will crack again, so you'd be wise to stitch the wall with some helical bars first. Then fill the crack with a cement slurry, then mesh across the wall, then plaster.

 

[opps]

Walls always move. Always. And you don't really want each side of an internal crack to move differently.

Your proposal will crack again, so you'd be wise to stitch the wall with some helical bars first. Then fill the crack with a cement slurry, then mesh across the wall, then plaster.

The wall seems to be thermolite. Wouldn't that suggest that the OP possibly has a cavity wall? I guess it could be solid though. My single story kitchen extension is solid thermolite. As an aside, if it is a solid wall with 200+mm thick walls, how deep do you need to chase into the mortar joins for the helifix bars? I ask because my external render has a crack. I did fit helifix bars but did so randomly, meaning that I was bridging the blocks rather than the mortar joins. On reflection, I only cut as deep as my cheap 125mm wall chaser would cut. Years later, the hairline crack reappeared (but not where I fitted the bars?).

Cheers Opps.

 

[^woody^]

The wall seems to be thermolite. Wouldn't that suggest that the OP possibly has a cavity wall? I guess it could be solid though. My single story kitchen extension is solid thermolite. As an aside, if it is a solid wall with 200+mm thick walls, how deep do you need to chase into the mortar joins for the helifix bars? I ask because my external render has a crack. I did fit helifix bars but did so randomly, meaning that I was bridging the blocks rather than the mortar joins. On reflection, I only cut as deep as my cheap 125mm wall chaser would cut. Years later, the hairline crack reappeared (but not where I fitted the bars?).

Cheers Opps.

Heli bars go at least mid way in the leaf IIRC, but that's for 100mm leaf. Some systems use two bars. It's best to confirm with the system manufacturer.

If you have aerated blocks, the most common cause of cracking is thermal, so if you stitch a crack and create a rigid bond, then it may well crack again in another place.

 

[ree]

Poster #8,
The OP twice says its an "inner wall".
The OP also says the crack appeared after a lintel was installed.
Nowhere does the OP say its a thermolite block.
The little of the block we can see is inconclusive ref ID.

 

[Nige F]

Poster #8,
The OP twice says its an "inner wall".

inner wall with a window sill.

 

[opps]

Poster #8,
The OP twice says its an "inner wall".
The OP also says the crack appeared after a lintel was installed.
Nowhere does the OP say its a thermolite block.
The little of the block we can see is inconclusive ref ID.

I suspect that the OP means the inner face of the wall, rather than an internal wall. My assumption is based on the fact that you can see a window sill and part of the frame.

Agreed, the OP does not say it is thermolite, but it definitely looks like aerated blocks. Zoom in on image 3, what else do you think it might be?

 

[^woody^]

I suppose it could be a 1970's serving hatch with glass slides. "In the bedroom" you'd ask, "Why not?" I'll say.

 

[Nige F]

Agreed, the OP does not say it is thermolite, but it definitely looks like aerated blocks. Zoom in on image 3, what else do you think it might be?

we'll never know