Cement type render found under plaster?

[hargcore]

Hi guys,

Due to damp problems I am planning to remove all plaster on one of my external walls (4 rooms / 4 walls) back down to brickwork. Install a damp proof membrane and bring in the plasterers to plaster over it.

The house is a 3 bedroom semi detached end terrace (1935-45).

When removing the plaster in the upstairs bedroom I uncovered a layer of what looked like cement render which the plaster was attached to. The layer is cracked and crumbling in a lot of places.


InternalRender001 by hargcore, on Flickr

What is this render made of and what is it's purpose? Any idea when this would have been done? The plaster is on very thin. Maybe they applied that so they could just skim the wall.

Either way I would like your opinion on what to do about it - I think it would be better to knock this off and expose the original brickwork then apply the membrane directly to that. The render would need a lot of repairs anyway due to it's state and it's not going to help with any damp problems.

Any feedback appreciated. Is this a common technique for internal finishes?

More photos of the render can be found here:
http://www.flickr.com/photos/hargcore/sets/72157627851493142/

 

[stevethespreader]

it looks like someone has painted aquaseal or blackjack on the render to try and get rid of the damp i could be wrong though but thats what it looks like

 

[joe-90]

That's breeze block That IS your internal wall.

Better off fitting insulated plasterboard to it or at least the silver papered stuff. Your problem is condensation - not damp.

 

[JohnD]

The house is a 3 bedroom semi detached end terrace (1935-45).

it's got cavity walls, has it?

which rooms is the damp in?

do the gutters and downpipes leak?

does anybody in your home drape wet washing around the house, or over radiators?

what sort of windows have you got?

 

[joe-90]

It's the Gestapo.

 

[hargcore]

Hi all,

Thanks for the responses.

Joe - Theres no joins like you would expect with breezeblock are you sure?

John - Not sure about cavity wall I want to take a few bricks out here and there to check if it has cavity wall insulation and if so what type and if it is wet.

The damp is in every room on the right external wall of the house. In and around (but not limited to) the chimney breasts.

I just got the house, there was £5000 worth of roofing work done before I got it. I think the rainwater goods were damaged and it was allowing water to run from the roof right down the external wall and behind the external render (which is cracked). No leaks since repair.

It's unihabited at the moment no washing etc.

Double glazed windows.

Cheers
Tom

 

[peaps]

Looks like either a strong cement mix or it's had an addertive to try cure the damp at some stage.

It also sounds like it has had some chimney problems as well as the roof. If you are going to use the fire place then put a mushroom on top to stop rain getting in and make sure all the pointing and lead work around it is sound, pots also. Personally I would knock all the crap render off and replater in lime render as it would have been done at the time of build. I would also rake out all the inside "pointing" on the breast and repoint with lime motor ten plaster.

If you intend on sealing it up then I would give it a good sweep, cap the pot and if you can get a small dehumidifier in the fire place do that to dry the chimney as much as you can, then you can install some air vents.

 

[JohnD]

I just got the house, there was £5000 worth of roofing work done before I got it. I think the rainwater goods were damaged and it was allowing water to run from the roof right down the external wall and behind the external render (which is cracked).

That would explain the dampness of the house.

Heat and ventilate it for a few months and the dampness will reduce.

A wet wall takes about a year to dry.

 

[joe-90]

I thought I saw pockets of rust that are synonymous with breeze block (clinker)

 

[peaps]

I thought I saw pockets of rust that are synonymous with breeze block (clinker)

It's brick behing the render.

 

[joe-90]

Oh right. Sorry I was mistaken then. Must be a strong mortar mix then.

 

[hargcore]

Thanks guys - Peaps, I think I'll remove it all. I want to get to the brickwork anyway to check for a cavity wall and I could repoint at the same time. The chimney was capped and the fireplace blocked with a wooden board - I cut a hole in the board to start venting it.

I'll go away and get it sorted and you'll probably hear from me again!

 

[peaps]

Thanks guys - Peaps, I think I'll remove it all. I want to get to the brickwork anyway to check for a cavity wall and I could repoint at the same time. The chimney was capped and the fireplace blocked with a wooden board - I cut a hole in the board to start venting it.

I'll go away and get it sorted and you'll probably hear from me again!

I,m in your area so PM me if you need advice.

 

[JohnD]

how thick is this "render?"

if you measure the thickness of an external wall (measure at a doorway or window) how thick is it?

Is the "render" visible on unplastered walls, e.g. in the loft or under the floor?

 

[joe-90]

Dunno what the OP is up to. He'll be hacking that stuff for weeks - but to what end? It won't sort his condensation problems.