Air Tightness - Methods

[richo106]

With our building work starting in couple of weeks there is just a couple of things to iron out and one being how to get as air tight as possible.

 

My plan currently:

 

Existing walls - brick, cement parge coat then another insulated backed PB or batten’d PIR, PB (not decide yet but need at least 50mm pir internally on existing walls

 

New Walls - Fibolite blocks, parge coat, dot and dab ( no need to insulate as in cavity)

 

I was thinking parge coat then I can fix cables and boxes direct to parge

 

I know there is other options out there like proper gypsum based parge, airtight paint and then bond and plaster.

 

I am electrician by trade but competent DIY’er and will be very hands on with the build.

 

As everyone I am trying to find a good balance between cost and effectiveness.

 

I would welcome some advice on what method works best/potentially cheapest as I can paint the paint etc 

 

Many Thanks 

 

 

[JohnMo]

My parge coat was a strong mix of soft building sand, cement and lime to give some flex.  Water down to a double cream consistency the use a broom to apply to walls.  An even think coat rubbed into the surface.

[richo106]

On 20/09/2022 at 17:30, JohnMo said:

My parge coat was a strong mix of soft building sand, cement and lime to give some flex.  Water down to a double cream consistency the use a broom to apply to walls.  An even think coat rubbed into the surface.

Oh right I just presumed parge coat was like a thin plaster coat that had to be put on by plasterers. 
 

what is the mix people use for it? Or can you buy ready to mix stuff that I can apply with a brush?

 

like this 

 

https://www.clayblock.ie/product/porotherm-parge-shop/

Seems a messy job but definitely doable  by myself. 
 

thanks again

[Iceverge]

Just a few bags of cement+lime from your local merchant and chuck in a mixer with some sand. 

 

It's cheap as chips. No need to buy anything more expensive. 

 

Trial and error will find a good consistently. 

[JohnMo]

normal cement, and hydrated lime.

 

I mixed mine as 1x 25kg bag of cement, 3x 25kg bags of building sand, and think it was about 2 to 3 shovels of lime. The lime gives a creamy consistency. Add enough water to make a double cream.

 

 You need to play with the mix slightly.

 

Makes a mess, wear safety glasses.