How do I seal this wall

[AliG]

We have a block (Porotherm) chimney breast in the kitchen.

 

The builders parged the inside walls of the house including the room side of the chimney breast

 

Despite repeatedly reminding them that that was an internal wall and someone had to go inside the chimney breast to parge the outside wall before the fire was installed it never got done.

 

The fire installers never sealed up the flue and I was hoping this was the main source of air leakage but now this has been done it still leaks.

 

Because the chimney breast has the TV and fire in it, there are numerous penetrations into it and these leak cold air when it is cold and windy outside.

 

Seeing that it is still draughty I opened it up today and you can see the gaps in the porotherm.

 

How do we seal this up? The only access is a TV shelf at the side which is around 300x600mm and the far away corners are around 1.5m away. We could try a long handle roller and some kind of parge coat, or should I just stand with a can of spray foam and spray it across the whole wall.

 

Also I was looking for some kind of smoke candle to try and pinpoint the exact sources of leaks. Does anyone have a recommendation?

 

Thanks

[nod]

Really poor block work

It should have been pointed and bar jointed as it was built

Chuck it back at the builder  

[AliG]

Porotherm doesn't get pointed on the vertical joints, these are normally filled by a parge coat over the whole wall. They should fill any abnormally large joints.

 

I think if you have an internal wall you just butt it up again the outside wall and connect it with wall ties.

 

Because it was internal and being covered by plasterboard I don't think anyone thought that filling the gaps mattered.

 

But this wall has a lot of penetration both to inside the house and outside, so there are a lot of air leakage paths.

 

 

 

 

 

[nod]

17 minutes ago, AliG said:

Porotherm doesn't get pointed on the vertical joints, these are normally filled by a parge coat over the whole wall. They should fill any abnormally large joints.

 

I think if you have an internal wall you just butt it up again the outside wall and connect it with wall ties.

 

Because it was internal and being covered by plasterboard I don't think anyone thought that filling the gaps mattered.

 

But this wall has a lot of penetration both to inside the house and outside, so there are a lot of air leakage paths.

 

 

 

 

 

Don’t agree 

 

I’ve put thousands of mtrs of parge on and it’s a waste of money 

for airtightness Correct pointing is far more effective 

Why on earth would you climb into a chimney to parge when you can simply point it as building 

 

Ours is BB and I could have parged the internal skin in a afternoon But chose to point 

On dot and dab the air shouldn’t get through to the block in the first place 

Ours showed no leakage at all around the PB 

Parge is useful for sound deafening But a waste of money for airtightness 

 

[AliG]

Porotherm just isn’t pointed.

 

Threre is no mortar in the vertical joints.

 

Elsewhere it looks like this -

 

Are you saying there should be no leakage past the plasterboard? That is right in the rest of the house. The problem here is that there are cables through the wall to the tv, there is a removable shelf in the wall for access to the cabling behind and there is a vent and access to the fire controls. All of these are difficult to seal so I need the wall behind to be better sealed. 

 

So so I have a combination of the area with the most penetrations in the house and the worst sealed piece of wall.

 

 

Edited August 18, 2019 by AliG

[Simplysimon]

got any young children? train them in pointing and send them up the chimney. just like the good old days!

[AliG]

Lol.

 

OK, I have investigated more now that the shelves are out and I can see inside the chimney breast.

 

It would help if it was windier.

 

The mastic around the flue has shrunk a little, so it is not sealed at the top. I can get that filled in.

 

There is a piece of flexible conduit through the wall near the bottom to an outside socket. I can put some mastic around the conduit which is pretty tight in the hole, but do people also seal up the inside of the conduit where the cables come through?

 

I took some IR pictures.

 

Here is the conduit-

 

 

 

 

 

 

Here is the back wall and the flue. You can see the cold area around the flue. Also it looks like the large gap between the side of the chimney breast and the outside wall is letting in cold air. Despite not being parged, the gaps between the Porotherm blocks do not seem to be cold, nor is there an issue at the top of the clockwork despite it not being sealed to the slab above.

 

So I will try and get these three areas sealed up.

 

Edited August 18, 2019 by AliG

[AliG]

A bit of searching suggestsI seal around the conduit then tape up the end where the cables come through.

[j_s]

Yes you will get air ingress through the conduit. I used 25mm conduit for various cables from bedrooms and lounge through loft and used rubber stoppas by pro clima both ends and I still had condensation build up at the top of the conduit in the loft so moist air from the house was still getting through. I ended up following advice on here from jsharris to use amalgamated tape