Parging for Air Tightness

[Triassic]

I’m in the process of laying the 140mm medium density blockwork that forms the front of my walk out basement. I’ve pointed up the mortar joints to eliminate any gaps and was thinking I should apply a parging coat.

 

So the question is which side of the blockwork do I parge and what mix should I use?

[bissoejosh]

Where/what is your airtight layer above the basement? How are you planning on finishing the outside of the blockwork?

[nod]

3 hours ago, bissoejosh said:

Where/what is your airtight layer above the basement? How are you planning on finishing the outside of the blockwork?

You should Parge the inside skin

Sand cement is ok 

But the caged sound coat plus is better and more convenient to use 

Around 90p per mtr But without the Harvey lifting of S C

[Triassic]

On 15/08/2018 at 17:36, bissoejosh said:

Where/what is your airtight layer above the basement? How are you planning on finishing the outside of the blockwork?

The airtight layer will be on the inner face of the timber frame, there will be a vapour permeable membrane on the outside. The basement has a block work internal all, a layer of insulation and limestone outside face. 

Edited August 18, 2018 by Triassic

[Triassic]

On 15/08/2018 at 21:14, nod said:

You should Parge the inside skin

Sand cement is ok 

But the caged sound coat plus is better and more convenient to use 

Around 90p per mtr But without the Harvey lifting of S C

Sorry you’ve lost me. What is “caged sound coat”?

[bissoejosh]

Similar to ours in some ways, blockwork wall below timber frame. I've just dressed the airtight membrane down from the frame onto the blockwork and will seal to the block with something like Gorband Fortax 6400 which is a mastic type product.  I think I'll then use mesh over the join before plastering to prevent cracking. The other option is to use a jointing tape with a built in fleece/mesh to deal with the cracking issue. 

[nod]

4 hours ago, bissoejosh said:

Similar to ours in some ways, blockwork wall below timber frame. I've just dressed the airtight membrane down from the frame onto the blockwork and will seal to the block with something like Gorband Fortax 6400 which is a mastic type product.  I think I'll then use mesh over the join before plastering to prevent cracking. The other option is to use a jointing tape with a built in fleece/mesh to deal with the cracking issue. 

We normally tack a plastic stop bead onto the block trapping the membrane Then Parge over 

[bissoejosh]

5 hours ago, nod said:

We normally tack a plastic stop bead onto the block trapping the membrane Then Parge over 

 

Would this be OK if going for an internal render finish?

[nod]

1 hour ago, bissoejosh said:

 

Would this be OK if going for an internal render finish?

Yes if your going for wet plaster backing coat There’s no need to Parge coat Simply trap the membrane and trim off the excess

[Declan52]

I used that fortax 6400 to stick my membrane to the blockwork. It's really sticky stuff.

Top tip don't get it in your hair only thing that takes it out is a razor.

[vfrdave]

On 18/08/2018 at 21:04, Declan52 said:

I used that fortax 6400 to stick my membrane to the blockwork. It's really sticky stuff.

Top tip don't get it in your hair only thing that takes it out is a razor.

I've got it in my arm hair and it's a pig to get out.

[Declan52]

9 minutes ago, vfrdave said:

I've got it in my arm hair and it's a pig to get out.

Cheap waxing kit for you then.