Dot and Dab

[nod]

I’ve made a start on the dabbing today

To those who already know this ignore this post

But we’ve had a few questions about air tightness and foam on block

Ive taken a couple of pictures

If you are paying a contractor to do this and it is any different than pictured Your not getting what you have paid for

and air tightness will be an issue further down the line 

Skirtings are decorative and shouldn’t need to be bunged up with foam

[Jeremy Harris]

You must be one of the tiny minority that put a decent peripheral run around the edges - 99% of dot'n'dabbers don't, and just create a plasterboard tent inside the house, with cold air able to get behind the boards easily.  Mind you, with no parge coat on the inside you're still going to get some cold air infiltration through the masonry, as it's generally pretty porous.

[lizzie]

I'm looking at getting dot and dab done in the garage to use up a lot of left over plasterboard......I have never seen an example of dot and dab before so very timely thank you.

[nod]

3 minutes ago, lizzie said:

I'm looking at getting dot and dab done in the garage to use up a lot of left over plasterboard......I have never seen an example of dot and dab before so very timely thank you.

Thanks Lizzie

As jerremy says most bother and cold air circulates right around the house Under skirtings and kitchen units

Ive been doing this for 35 years

it really doesn’t take much more time to do it right

Much easer to straighten and fix to 

[Nickfromwales]

Not too shabby . 

[Luckylad]

On 24/03/2018 at 16:50, JSHarris said:

no parge coat on the inside you're still going to get some cold air infiltration through the masonry, as it's generally pretty porous.

Hi

Is the parge coat really worth doing?

Does it make the airtightness that much better?

[richi]

An alternative to a conventional parge coat is to paint a 25% PVA solution (a tip given to me by the Passivhaus-savvy brickie who bought our old garage door)

[Jeremy Harris]

7 hours ago, Luckylad said:

Hi

Is the parge coat really worth doing?

Does it make the airtightness that much better?

 

Uncoated masonry is pretty air permeable, so coating definitely makes a very significant improvement.  However, a lot depends on the nature of any structure or insulation outside the inner masonry leaf.  Some types of insulation, for example, can act as a pretty good wind barrier, as can some forms of outer wall finish.

[Luckylad]

5 hours ago, richi said:

PVA solution

Thanks for the suggestion but I don’t think  it would work because you wouldn’t be able to build up a thick enough layer of pva.

18 minutes ago, JSHarris said:

air permeable

Previously we’ve only done a parge coat for sound proofing behind dot and dab.

I was undecided whether to do it on my own house.

Having seen your suggestion and read up on it, I’ll do it for airtightness ,on my own house,but it’s not something builders want to pay for.

[richi]

1 hour ago, Luckylad said:

Thanks for the suggestion but I don’t think  it would work because you wouldn’t be able to build up a thick enough layer of pva

 

I was dubious too, but the guy certainly seemed to know his onions, and had decades of experience.

 

I didn't PVA mine, because I wanted "proper" plaster.