External Cracks Between Original House & Single Story Extension

grumbler

Well, let's agree to disagree.

What's "the post from an SE"?

stuart45

grumbler said:

Well, let's agree to disagree.

I'll agree to that.

weeg

To actually answer the OP, it's a pretty poor design having the door hard against the original building. There's a few possible explanations, and anything anyone says here can't be more than speculation without seeing the building in real life. 
That's a uPVC door, and it's possible that some structural timbers were removed when it was installed. Or the lintel bearing isn't adequate. Or the founds are inadequate. Or the extension was never properly tied back. My guess would be it's an issue with the door opening, but it depends on the age and construction of the extension, as well as where in the country it is.

grumbler

weeg said:

stuart45 said:

A wall starter stops a wall moving away from the wall, not downward settlement, that's what their job is.

I'm with him on this. Obviously if the rest oft he design is wrong it won't stop a major issue, but we specify wall starters specifically to keep the new and old walls hard against each other.

If it's a common confusion it's one shared by every structural engineer I've ever worked with. It's a tension system, not a shear system.

I am glad to hear that at least 'every every structural engineer' agrees with me. And, naturally, I disagree that they are 'confused'.

stuart45

grumbler said:

weeg said:

stuart45 said:

A wall starter stops a wall moving away from the wall, not downward settlement, that's what their job is.

I'm with him on this. Obviously if the rest oft he design is wrong it won't stop a major issue, but we specify wall starters specifically to keep the new and old walls hard against each other.

If it's a common confusion it's one shared by every structural engineer I've ever worked with. It's a tension system, not a shear system.

I am glad to hear that at least 'every every structural engineer' agrees with me. And, naturally, I disagree that they are 'confused'.

I don't think weeg agrees with you on this.

grumbler

My understanding is that he agrees with you and disagrees with SEs.

weeg

grumbler said:

weeg said:

stuart45 said:

A wall starter stops a wall moving away from the wall, not downward settlement, that's what their job is.

I'm with him on this. Obviously if the rest oft he design is wrong it won't stop a major issue, but we specify wall starters specifically to keep the new and old walls hard against each other.

If it's a common confusion it's one shared by every structural engineer I've ever worked with. It's a tension system, not a shear system.

I am glad to hear that at least 'every every structural engineer' agrees with me. And, naturally, I disagree that they are 'confused'.

No. I don't agree with you, nor would my colleagues*. I'm not confused about this. Wall starters are designed to stop the new wall pulling away from the old wall, in exactly the same way that wall ties are designed to hold two  skins together. If the rest of the building has been done wrong it won't stop a catastrophic collapse.

*who are, like me, consulting structural engineers. Domestic houses are my literal day job. I can't speak for 'every structural engineer'. But I do know a lot of us.

stuart45

No, weeg is an SE and says that if what you stated about people being confused about the use of wall starters is correct, then all the SE's weeg knows is also confused.

weeg

grumbler said:

My understanding is that he agrees with you and disagrees with SEs.

*She* agrees with stuart.

grumbler

Yes, I see, I misunderstood him.

BTW, I have background in mechanics in general and structural integrity in particular. So, I am in position to argue even with SEs.

I can only repeat - typical wall starter kit by it's design is meant to hold the new wall from falling.