Opening up fireplace (builders opening)

[vinn]

That looks great. Again, a very neat job.
But I thought the idea was to open up to the concrete lintel - is there a new reason for this height dimension?

 

[sprite1275]

That looks great. Again, a very neat job.
But I thought the idea was to open up to the concrete lintel - is there a new reason for this height dimension?

Yeah just felt too high. I also had some people suggest the lintel was not sitting on the bricks far enough so killed 2 birds with one stone.

Got to figure out how to plaster it up now.

 

[sprite1275]

That looks great. Again, a very neat job.
But I thought the idea was to open up to the concrete lintel - is there a new reason for this height dimension?

Vinn, you said not to use gypsum on the chimney, why?

I've knocked all the old plaster/render off and want to crack on. How's best to go about it? Bond it, brown it or plasterboard it or should it be rendered?

Not sure what to do.

 

[vinn]

Its best to render chimney breasts in sand and lime 3:1 mix or say Dricoat with a remedial finish - the earlier reference to gypsum was to inside the fire opening but it applies to the whole breast.
Why, because its a barrier to soot penetration.
However, there's no need to knock off all the plaster on the c/b unless its required?

 

[sprite1275]

Its best to render chimney breasts in sand and lime 3:1 mix or say Dricoat with a remedial finish - the earlier reference to gypsum was to inside the fire opening but it applies to the whole breast.
Why, because its a barrier to soot penetration.
However, there's no need to knock off all the plaster on the c/b unless its required?

I've already knocked it all off as it sounded hollow (blown from wall) what kind of finish Will sand and lime give? I want smooth plaster type finish.

 

[vinn]

You skim the S&L with a Remedial finish such as Limelite.

 

[sprite1275]

You skim the S&L with a Remedial finish such as Limelite.

Thanks vinn. Just to clarify as I've not rendered before. I just mix 3 sand to 1 lime add water (no cement?) and spread it on the wall like a bonding coat?

Do I pva wall first?

 

[vinn]

Yes.
No.
Scratch on a very tight first scratch coat.
Any sign of damp or salts use plastics angle beads.

 

[sprite1275]

Yes.
No.
Scratch on a very tight first scratch coat.
Any sign of amp or salts use plastics angle beads.

Gave the chimney a bit of a sweep today. Going to fit cement board in the cavity tomorrow and have a go at rendering.









Got me some 3.5 nhl hydaulic lime today and some plastering sand. I take it you mix this stuff pretty thick ?
I've also got some glasroc multiboard to line the inside of the cavity. Supposed to be heat resistant like hardiebacker.

 

[vinn]

Mix 3:1 or 4:1 but dont mix it too stiff.
Mix half a bucketful at first, slightly sloppy, and see if you can trowel a tight scratch coat on.
Then fix the angle beads at outside corners, & let them dry on before applying the floating coat.
Take out suction as you go.

 

[sprite1275]

Mix 3:1 or 4:1 but dont mix it too stiff.
Mix half a bucketful at first, slightly sloppy, and see if you can trowel a tight scratch coat on.
Then fix the angle beads at outside corners, & let them dry on before applying the floating coat.
Take out suction as you go.

The stop beads I've got are 10mm so I take it the first 'tight' scratch coat should be around 3mm and then another scratch coat of say 5mm.

After this I've got limelite for the finish.

 

[vinn]

So you are using stop beads not angle beads?

Is it Limelite finish?

Mixing a little finish powder with the S&L fixing
dabs will allow for a quick set on the beads.

 

[sprite1275]

So you are using stop beads not angle beads?

Is it Limelite finish?

Mixing a little finish powder with the S&L fixing
dabs will allow for a quick set on the beads.

The stop beads will be lining up with the edge of the glasroc which is lining the internal cavity so will be going around the opening. I've got corner beads for the chimney breast corners.
In thought if I do a thin scratch coat I would just push the beads onto that.

The limelite is renovating plaster.

 

[vinn]

Use dabs to fix the all the beads - 15mm and 20mm stop beads are available.

There is a Limelite backing plaster and a Limelite finishing plaster - which do you have?

 

[sprite1275]

Use dabs to fix the all the beads - 15mm and 20mm stop beads are available.

There is a Limelite backing plaster and a Limelite finishing plaster - which do you have?

Ive bought this http://www.pozament.co.uk/products/limelite-renovating/ I take it its wrong

Also are you saying use 15mm beads?