Unprotected External Concrete Block Wall & Damp

[Hadventure]

I am considering buying a new build house (2 years old).

Part of the external wall at the rear, the bottom part concealed by a party wall, is constructed of concrete blocks  As far as I can see the wall is not rendered  so I can see the concrete blocks.  The upper part is made of brick (expensive reclaimed ones).

The un-rendered concrete block part is about 1-2 inches away from the party wall at the boundary of my land.  As the party wall is parallel and close to the entire concrete block part it seems somewhat protected.  The gap is a little protected from above by my roof gutter.  But there is still a gap and water could get in.

Is this common practice or acceptable?   

Is there anything that could be done to protect this part of the wall?  It would be hard to paint with chemicals or render as you cannot get into the space between it and the party wall.  I could put lead flashing across the top to close the area off but I'm not sure what the neighbours would think?

My surveyor seemed to think with a gutter between the two Walls it would be fine.  

I have been inside the house and it seems dry, but it is dry-lined so I guess It would be difficult to tell. 

I really like this property and it is perfect otherwise but I'd hate it to become damp or be an issue if ever I sell it.  

Any advice would be greatly appreciated! Thanks

 

[freddiemercurystwin]

No clue what you're saying really, got a photo? If its cavity walls and this on the outer skin it doesn't matter if its rendered or not. There's a cavity between the inner and outer skins. BTW more often than not homebuyers surveyors are carried out by poorly experienced types.

 

[Hadventure]

Hi thanks for your reply!

Sorry it's difficult to explain, I'll try and make it clearer.  There is a cavity and this is the external wall I'm concerned about.

Basically part of an external wall of the property is made of concrete blocks (they look like the old breeze blocks but a different colour). 

I thought that exposed concrete blocks needed to be sealed to prevent damp entering.

The part of the wall made of blocks is difficult to see and photograph as it is very close to another brick wall. 

I'm presuming they used cheaper materials blocks rather than the decorative bricks used for the rest of the house because it is not visible.  But I am concerned they are relying on the adjoining wall to protect the exposed concrete blocks.

Do all external concrete block Walls need protecting? Or is it ok if they are the outer wall where a cavity is present.

Regarding surveyors I have read some horror stories which is why I am checking this out myself.  I had though his damp meter thing would 'solve the problem' but was told you can't tell when it's drywall!

To be honest he said "well it's been two years and it doesn't seem damp..."   And I almost flipped - as if I needed telling that! 

 

[freddiemercurystwin]

The purpose of any external skin be-it a block wall, brick wall, timber cladding, tiles or whatever is purely as a first defence rainscreen and to allow any water that does penetrate it to run down its inner face down the cavity where it lands (hopefully) on a cavity tray and out through a weephole so cannot enter the inner skin and cause any damp problems. That's the whole ethos behind a cavity wall system. So frankly a bit of render missing from the external leaf is not something to get worked up about and IMO (without seeing a photo) not a reason to avoid buying a house.

 

[Hadventure]

Untitled

• Hadventure
• 2 Oct 2011
• 1

I hope that link works! Its not the best photo but the tag explains what you are looking at.

The Top is the actual top of the boundary wall between my house and my neighbours garden, looking down from above. The bottom is some lead flashing that is present where the brick changes to concrete block (at the level of the top of the boundary wall). In the gap you can just make out the concrete blocks which extend down for about 6 feet and are pointed quite badly.

Thanks for the comments.

So are concrete block not drawing and porous?

 

[Hadventure]

Also how could I seal this wall? Any suggestions with such limited space?

Thanks

 

[freddiemercurystwin]

How could you seal the wall indeed and how would you have expected a builder to do a better job when the only way access can be provided is to take down the boundary wall?

External skins are not impervious to moisture/water ingress whether they are rendered or no although render will go far to prevent water ingress. Again re-read my post about cavity walls, everything there is still relevant and should allay your fears. Given that there is a dirty great existing wall in front of it certainly no wind driven rain is going to get through the wall.