Rendering Bricked Up Garage Door

[keyplayer]

Picture:
A garage converted to a living room, with the up and over door removed and the space filled with blockwork, to be rendered. I'm just wondering, where the new render meets the existing on the three sides of the old door area, is it best practice to chip away a band of existing render in order to include a strip of eml to marry new and existing, or just float up to existing perhaps using an sbr bonding agent around the edge?

 

[roughcaster]

It's a pity you never broke out a few blocks either side in the existing walls before you blocked in the old opening. That way, you could have "bonded in" the new blockwork to the old.
The way you suggested,, cutting back some of the existing render, fitting EML, then marry new render to old, would be an alternative, but you couldn't guarantee it wouldn't crack.
I personally wouldn't bother with the last option.

 

[keyplayer]

It's a pity you never broke out a few blocks either side in the existing walls before you blocked in the old opening. That way, you could have "bonded in" the new blockwork to the old.

No problem, the door's still there at the moment and the brickie is yet to start. He was talking of tying the two walls together using straps, although I'm not sure at the moment exactly what type. I'm imagining of the type that bolts to the existing wall and sits in the mortar bed? Is this as good as your way? And presumably you'd just render out flush with the old without trying to marry the two renders together?

 

[roughcaster]

I know what you mean by the bolt/strap method, but you will still have a "straight joint" either side of the old door doing it that way, so more liable to crack.
By cutting out every other block per course, from the each side of the existing wall/s, the builder can then lay the new blocks/bricks, and "bond" them into the existing blockwork, so you will "not have straight joints" in the wall,, it will be "keyed into" the existing blockwork,,, a much stronger job, although more time consuming. You could always cut them out yourself in preparation for the builder.
As regards to re-rendering into the existing render, i'd still cut it back 6 to 8 inches or so, and then marry it in to the existing. You'll always see it as a "patch" though, unless you prep, scratch and re-render over the whole wall.

 

[Micilin]

As said by RC the best way is to 'tooth in' the new brickwork.

 

[keyplayer]

Thanks gents.