Breathable Membrane

[Recci]

If you have blockwork wall with cladding like below.
Why do you not need a waterproof membrane in front of the blockwork?

 

[Recci]

Quick question why are breathable membrane pointless to fix to blockwork ?

 

[Recci]

Blockwork doesn't need protected, unlike a timber frame.

Why is that? Blockwork is porous

 

[Mr Chibs]

Doesn't the foil on the insulation provide a vapour barrier? if it's taped up.

 

[freddiemercurystwin]

Post little your sense makes.

 

[freddiemercurystwin]

The breathable membrane is on the face of the insulation, so will not allow moisture or rainwater to penetrate (from outside into the insulation (or into the blockwork)) but will allow vapour to pass from the inside out.

 

[Recci]

Why do you not need breathable membrane for blockwork when it is porous?

 

[denso13]

Blockwork doesn't "breathe". It doesn't need a membrane.

 

[DiyNutJob]

You can add it if you want to.

What is you reasoning for wanting membrane? Membranes are normally used for the roof, where there is higher probability of water penetration. On a properly built house, when there is no unusual defect or leak, the chance of water penetrating the wall is low. Therefore membrane isn't used.

 

[Recci]

So what? Blockwork doesn't need protected from moisture.

Even for timber frame the vapour barrier would be on the warm side (inside), not in the cavity.

For water penetration

 

[Recci]

You can add it if you want to.

What is you reasoning for wanting membrane? Membranes are normally used for the roof, where there is higher probability of water penetration. On a properly built house, when there is no unusual defect or leak, the chance of water penetrating the wall is low. Therefore membrane isn't used.

Stop water penetration? I believe the foil facing insulation will do it that and drained cavity

 

[freddiemercurystwin]

You can add it if you want to.

What is you reasoning for wanting membrane? Membranes are normally used for the roof, where there is higher probability of water penetration. On a properly built house, when there is no unusual defect or leak, the chance of water penetrating the wall is low. Therefore membrane isn't used.

Wherever there is a clear cavity (ie in a traditional block + insulation + cavity + brick/block wall construction) you do not need a membrane because any rainwater getting through the outer skin will trickle down the inner face of the outer skin.

However in the example posted in the OP's other thread, the cavity is not clear, there are timber battens bridging the cavity so there is potential for rainwater to contact with the insulation - therefore a membrane is used as a barrier to prevent the rainwater from contacting the insulation and in fact the notes in the diagram state that the insulation is protected by a membrane, though it has not been drawn.

 

[DiyNutJob]

Should merge the threads or things will get confusing.

The diagram shows insulation having membrane in front already. Is the OP asking for membrane behind the insulation?

 

[Recci]

Is soild blockwork porous and permeable ?

 

[denso13]

To an extent, they're not water resistant.