New straight wall built. Moves away from original

[pilsbury]

I'm currently building my outer skin for my side extension. This outer skin is a continuation of the existing wall. It's being built out of block to be rendered as will the existing brick wall so it matches in.

I was aware the existing wall wasn't truly plumb. Leans out slightly at the top. I had 2 choices. Either follow the existing wall out of plumb, or build my new wall true. I chose the latter. So my new outer skin starts level with the old wall at the bottom, but at the top my new wall is recessed almost an inch.

Firstly, did I make the right choice? Secondly, can this step be hidden with render to level it all out?

 

[^woody^]

It can't be hidden as you will presumably be fitting a movement joint in the render where the new wall joins the existing.

 

[pilsbury]

hmmmm... movement joint? Here's where I show how amateur I am. What would a movement joint consist of and how do you put one in? Why can my "step" not be hidden?

 

[KenGMac]

pilsbury, good evening.

With due respect to "Woody" i think that you can [to a certain extent] mask the worst effects of the "Step" that you may end up with

How about you consider?? the following??

Fit a 100.mm Dia. plastic pipe directly over [in front of] the junction? it should be wide enough to make viewing the "Step" difficult? Simply fit the pipe by sticking the lower end into the ground and as for the upper end? a swan neck with a plastic ball cover.on top, the pipe is doing nothing apart from acting as a visual divergence?

Ken.

 

[pilsbury]

Ken - I like your thinking! I'd still like to try and render it out flat.... In my novice brain I was thinking of a thin scratch coat on the brick side and a thick scratch coat on the recessed block side then a top coat to smooth the difference out. From Woody's response it sounds like I may be in for cracking at the join of the walls.

However, I do need a downpipe from the gutter somewhere going to a soakaway. I'd rather it at the far end but may use your idea to cover up the bodge!

 

[23vc]

I think the movement joint will consist of a stop bead each side of the wall join as if you didn't put it in it would likely crack at that point. But obviously that rules out rendering over the join and hiding it. As above, Drain pipe is the classic fix for this kinda thing isn't it

Edit: I guess you could eml the area say a foot each side and render over, but may still get cracks

 

[pilsbury]

I think the movement joint will consist of a stop bead each side of the wall join as if you didn't put it in it would likely crack at that point. But obviously that rules out rendering over the join and hiding it. As above, Drain pipe is the classic fix for this kinda thing isn't it

With the stop bead as a movement joint, which by googling shows it is fixed on one side, could this not be bastardised and fixed into place then thicker/thinner coats of render be applied to the appropriate sides? If I were to render using the minimum accepted thickness of render on the brick side and the maximum thickness on the block side, then surely this would even it out?

Edit: I guess you could eml the area say a foot each side and render over, but may still get cracks

What is EML?

 

[stuart45]

Expanded metal lath.

 

[^woody^]

An extension will move. Any render across the abutment joint will crack, no matter how thick or how blended you try and make it. If you don't deal with that, then you have a route for water to get behind the render.

Hiding it is separate.

 

[pilsbury]

Ok then, a render expansion strip is certainly on the cards - just need some creative thinking how to fix the levels.... or a downpipe if all else fails..... or some clematis on a trelis!

 

[John D v2.0]

In our extension the architect specified a "shadow gap" to hide any difference and crack or movement at the joint. Not that the builder bothered with any of that, now we have a small crack, but basically it looks reasonable roughcasted over. If it's at the side of the house it's not as bad.
We also had a join at the back so we specified external wall insulation on the old house wall, so the render is the same where you'd notice more.

 

[Alastairreid]

Even if toothed in settlement of the new build will crack along the join.
Expansion/settlement joint should be specified anyway.