Rendering celcon blocks

[luke105]

Evening all,

I have asingle story building with celcon blocks that I need to render. I’m thinking my options are either making a brush on slurry of sbr, sand, cement, water, wait to dry then scratch coat as normal.

Or would galvanised steel mesh be a better option?

or am I well out and someone here has done a few of these and found something that works? Ratios would be great.
Thanks.

ps, the building has had an alteration after completion hence the odd block work to the left of the door. Not looking for comments on this. Thanks again.

 

[Cockney]

Evening all,

I have asingle story building with celcon blocks that I need to render. I’m thinking my options are either making a brush on slurry of sbr, sand, cement, water, wait to dry then scratch coat as normal.

Or would galvanised steel mesh be a better option?

or am I well out and someone here has done a few of these and found something that works? Ratios would be great.
Thanks.

ps, the building has had an alteration after completion hence the odd block work to the left of the door. Not looking for comments on this. Thanks again.

Ok no mention of the shoddy block work then. ............Wtf happened above the door

 

[The Hobo]

Ok no mention of the shoddy block work then. ............Wtf happened above the door

don't tell building control

 

[Cockney]

don't tell building control

Looks like it’s been bloody cut with an old set of dentures mate.

 

[The Hobo]

Looks like it’s been bloody cut with an old set of dentures mate.

cover strips where a good invention tell him

 

[Monkey Boy]

You need to slurry that and at least press Fibrous mesh mat into your scratch as you go. EML sucks imo
PS
I’ve never done it

 

[The Hobo]

will the door handle not break the kitchen window

 

[luke105]

Ok no mention of the shoddy block work then. ............Wtf happened above the door

the upvc cladding had to be cut out to make way for the door. It needs an end trim putting on around the cut out that’s all. The block work has been patched in as there was a window there. The block work doesn’t need to be the Mona Lisa when it’s being rendered. The steel straps will connect the old and new block work together hence why they are there.
Now that’s been explained any help on the actual rendering would be great.
Thanks.

 

[Spray]

If you want a system that works it’s 2 coats of micro gobetis parex primer and then 15mm of Parex monorex with mesh

 

[luke105]

will the door handle not break the kitchen window

The door has a metal bar at the top and bottom which prevents the door opening that far. Although the door handle Doesn’t reach that far Over the window sill to actually hit the glass.

 

[The Hobo]

The door has a metal bar at the top and bottom which prevents the door opening that far. Although the door handle Doesn’t reach that far Over the window sill to actually hit the glass.

wow all hi tec stuff

 

[luke105]

wow all hi tec stuff

Now let’s stick to the rendering and give me an answer

 

[Cockney]

the upvc cladding had to be cut out to make way for the door. It needs an end trim putting on around the cut out that’s all. The block work has been patched in as there was a window there. The block work doesn’t need to be the Mona Lisa when it’s being rendered. The steel straps will connect the old and new block work together hence why they are there.
Now that’s been explained any help on the actual rendering would be great.
Thanks.

What material is being used?

 

[The Hobo]

Now let’s stick to the rendering and give me an answer

i aint a spread lol

 

[Spray]

Now let’s stick to the rendering and give me an answer

Luke just gave you the answers

 

[luke105]

What material is being used?

I’d like to use sand and cement render really just to keep cost down however I can get hold of Weber Bagged one coat render so that is an option.

 

[luke105]

If you want a system that works it’s 2 coats of micro gobetis parex primer and then 15mm of Parex monorex with mesh

HI thanks for reply. I’ve only done sand and cement and Weber one coat before so I’m not confident in trying a costly product. Sorry I should have probably mentioned this.

 

[luke105]

The big issue and main reason for the post is the suction issues with celcon blocks...ie, blocks sucking the the water out of my mix. Preferably sand and cement or Weber one coat system and I’m just hoping someone has rendered over celcons before and has found a method that works well. Cheers

 

[Stewie03]

If your going down the s&c route your mixes need to be spot on over lightweight blocks,or the whole thing is pointless,if this job is for a paying customer I would walk away from it no point chancing it if you haven't rendered on lightweight block before

 

[luke105]

If your going down the s&c route your mixes need to be spot on over lightweight blocks,or the whole thing is pointless,if this job is for a paying customer I would walk away from it no point chancing it if you haven't rendered on lightweight block before

It’s my own so it’s not an issue. But the same time I don’t want to go through it all and it fall off wasting my time.
do you know the correct method and ratios?

 

[Monkey Boy]

I’ve rendered over celcon. I pva’d em, not water proof pva either!
Now that comment is gonna get people wanting to leave this forum I know - Or ask Danny to boot me off!
As sure as eggs is eggs it will crack unless you put mesh in

 

[luke105]

I’ve rendered over celcon. I pva’d em, not water proof pva either!
Now that comment is gonna get people wanting to leave this forum I know - Or ask Danny to boot me off!
As sure as eggs is eggs it will crack unless you put mesh in

Ok so you think, pva the blocks....allow to fully dry (overnight whatever) then sand and cement scratch coat with mesh...then after that just top coat as normal?

 

[Monkey Boy]

Ok so you think, pva the blocks....allow to fully dry (overnight whatever) then sand and cement scratch coat with mesh...then after that just top coat as normal?

Yeah I do
That mesh you get in a meter wide roll
But I’m aware sbr slurry is really the consider’d best method. Just think buildings need to breathe myself?
But first Try pm @Rigsby the rendering ninja he would advise best or @church

 

[luke105]

Yeah I do
That mesh you get in a meter wide roll
But I’m aware sbr slurry is really the consider’d best method. Just think buildings need to breathe myself?
But first Try pm @Rigsby the rendering ninja he would advise best or @church

Thanks.
I do like the slurry option to be honest but happy to go with someone who’s actually done it! Mesh as in not the steel mesh but the fibreglass mesh stuff?

 

[Monkey Boy]

Thanks.
I do like the slurry option to be honest but happy to go with someone who’s actually done it! Mesh as in not the steel mesh but the fibreglass mesh stuff?

Fibre yes, towel it in as you go in patches.
Steel starts going down the three coat work route cos of the over lap thickness
Get more replies to this thread before listening to me

 

[luke105]

Fibre yes, towel it in as you go in patches.
Steel starts going down the three coat work route cos of the over lap thickness
Get more replies to this thread before listening to me

so I’m hoping slurry, scratchcoat with mesh, then top coat normal. Just need the best ratios if anyone can assist

 

[Spray]

HI thanks for reply. I’ve only done sand and cement and Weber one coat before so I’m not confident in trying a costly product. Sorry I should have probably mentioned this.

Well parex is similar to Webber pal and will work over these blocks

 

[Spray]

so I’m hoping slurry, scratchcoat with mesh, then top coat normal. Just need the best ratios if anyone can assist

Again just use a bagged render then ratios are sorted

 

[luke105]

Again just use a bagged render then ratios are sorted

Won’t there be suction problems even with bagged render?

 

[Djr]

I’d like to use sand and cement render really just to keep cost down however I can get hold of Weber Bagged one coat render so that is an option.

Yes

 

[johniosaif]

You can just lightly water the blocks , don’t soak it , apply sand/ cement at 5/1 with a water proof as a scratch . Then the top coat can be 5/1:1 sand cement/lime or even 6/1 .
a splatter coat slash scud coat before scratch isn’t a bad idea.
No fn pva .

 

[essexandy]

Just get it rendered with the correct strength gear.

 

[Ftp321]

Whatever happens rendering on aerated blockwork is a risk and disclaimer should be put in place,
Render layers should be progressively weaker so you're already fucket because the substrates weaker than the render, don't know why building control and architects still come up with the idea knowing that it's got to be rendered,
I would use a pre bagged high polymer fibre reinforced adhesive render with mesh laid in and stipple coated or keyed such as
Rendaid
Key coat primer
Sp22

 

[luke105]

You can just lightly water the blocks , don’t soak it , apply sand/ cement at 5/1 with a water proof as a scratch . Then the top coat can be 5/1:1 sand cement/lime or even 6/1 .
a splatter coat slash scud coat before scratch isn’t a bad idea.
No fn pva .

Thanks for your reply. Have you done this before? This was the method I was hoping for.

 

[beader]

It’s my own so it’s not an issue. But the same time I don’t want to go through it all and it fall off wasting my time.
do you know the correct method and ratios?

Can i ask why you chose to build it using celcon blocks in the first place?