Parging Durisol: another steep learning curve.

[ToughButterCup]

I got a PM from a member who is about to parge his Durisol build.  On my build, as usual, I had never done this before. So this is a brief review of what, how, when .... and mostly it demonstrates yet another steep learning curve.

Here's what I wrote about it at the time

 

And this is the result ; each photo has a brief annotation to help explain.

 

This photo shows two levels of parging - the RHS parging is thicker, much thicker than the LHS. You can hardly see the blocks

 

I've chosen this photo (of the damaged corner) because it shows clearly the difference in thickness in coating: LHS much thicker

 

Here's the spiel about rendering and airtightness  : thing is from experience, I don't think you can get airtightness out of the parge coat alone : well, I can't anyway. Much more airtightness might well be provided by the following covering ( in our case ) Clober Permoforte Quattro. And, at that price, it should provide that. It's excellent by the way.

Put an  good plaster coat inside and you're well on the way to a decent breathable, airtight wall.

 

Thing is - what happens in way of (behind) the wall plates. I think I've missed a trick there.

 

Here's the point: I should have made the coating thicker. 

[Russell griffiths]

What is the normal method of air proofing woodcrete blocks?

has anybody used either a spray on plaster or a spray on airtight liquid membrane 

 

it seams to be a problem im coming across lately without any firm answers. 

[SteamyTea]

So is Durisol no airtight once the concrete is poured?

[Russell griffiths]

3 minutes ago, SteamyTea said:

So is Durisol no airtight once the concrete is poured?

Nope, none of the woodcrete blocks are as far as I’m aware, happy to be told I’m wrong. 

[SteamyTea]

Just now, Russell griffiths said:

Nope, none of the woodcrete blocks are as far as I’m aware

But that polystyrene ICF is, yes?

[Russell griffiths]

Just now, SteamyTea said:

But that polystyrene ICF is, yes?

It’s about having a continuous concrete core, any block can be airtight if it has a continuous 150mm layer of well vibrated concrete. 

Its the block junctions where you have two layers of woodcrete touching each other, the woodcrete is a poor air tight layer and the gaps between the blocks even worse. 

Unless you where to use a can of squirty foam between each block they are inherently gappy and require a second airtight method. 

 

 

[nod]

I’ve always parge coated the inside with bagged sound coat Cheap and quick 5 mil thick

[ToughButterCup]

1 hour ago, nod said:

I’ve always parge coated the inside with bagged sound coat Cheap and quick 5 mil thick

 

Oh that word '... always...' 

Makes a first and only time self-builder jealous. Just think Gary, you'll have forgotten more than I'll ever know about parging.