Laying a slate hearth on limecrete.

[Rageyboy91]

Hey guys,

I have a chunk of slate comming for my hearth, 30mm thick, I'm setting it above the laminate so I created a concrete bed around 2cm, so the boards will slide under to create a nice finish.

But I'm not sure what to use to stick it down, I want about 5mm, I was thinking flexible tile adhesive but not sure this correct?

I have concrete, sharp sand and nhl3.5 left, so I was thinking I could just lay it on some weak mortar mix?

What would be the correct way?

Cheers,

Matt.

 

[Terrywookfit]

I have used gobbo to bed all types of hearths including Marble.
If there are any porous joints seal with PVA to prevent staining due to capillary action

 

[Rageyboy91]

I have used gobbo to bed all types of hearths including Marble.
If there are any porous joints seal with PVA to prevent staining due to capillary action

cheers for reply. Didnt realise gobbo was slang for cement mortar. I'll pva prime it then bed it on mortar, going to save me money doing it like that anyway

 

[lostinthelight]

Hey guys,

I have a chunk of slate comming for my hearth, 30mm thick, I'm setting it above the laminate so I created a concrete bed around 2cm, so the boards will slide under to create a nice finish.

But I'm not sure what to use to stick it down, I want about 5mm, I was thinking flexible tile adhesive but not sure this correct?

I have concrete, sharp sand and nhl3.5 left, so I was thinking I could just lay it on some weak mortar mix?

What would be the correct way?

Cheers,

Matt.

Out of interest, did you lay limecrete on top of compacted foamed glass aggregate ?

 

[Rageyboy91]

Out of interest, did you lay limecrete on top of compacted foamed glass aggregate ?

No, . Hopfully itll be ok, it's only 2cm thick. Going to bed it on mortar today actually wish me luck.

 

[tell80]

You should be fine - just use whatever you have to hand to mix a bulking up and adhesive mix.
Lightly butter the back of the slate before dropping it into place.
Presumably you've made a template and then dry fitted the slate?

I notice 3 x holes in the fireplace soffit - are these holes for flue ventilation?

 

[Rageyboy91]

You should be fine - just use whatever you have to hand to mix a bulking up and adhesive mix.
Lightly butter the back of the slate before dropping it into place.
Presumably you've made a template and then dry fitted the slate?

I notice 3 x holes in the fireplace soffit - are these holes for flue ventilation?

that's my plan if all goes well! I never got around to fitting it as another diy task took all day lol.

Cheers for the advice, I was going to pva the back and seal it then do as you suggested. Is it worth the pva? Think slates pretty impenetrable as they were used for dpc right?

I was just going to knock up a very weak mix of lime NHL 3.5 and concrete. building sand 6 /1 lime / 0.5 cement.

And yes the holes are for ventilation, I've got a bio burner going in there so I like the idea of some of it the co2 going up the chimney.

 

[tell80]

You dont need anything special, why not roughly use the mix I gave you - you dont need lime or Pva but they wont do any harm.

Installing a burner of any kind needs a heads up from a Burner Installer and/or a GaSafe.
And an hard wired alarm.

 

[lostinthelight]

I've got a 30 mm slate hearth on level cement base set on runs of construction adhesive. It's been there no problem with a WB on top for nearly 7 years with no issues.
I'm curious to know, why all the complications with lime and pva?

 

[Rageyboy91]

You dont need anything special, why not roughly use the mix I gave you - you dont need lime or Pva but they wont do any harm.

Installing a burner of any kind needs a heads up from a Burner Installer and/or a GaSafe.
And an hard wired alarm.

Yeah will do cheers, I got confused with sealing the porous areas.

It's a bioethanol burner I couldnt find any regs on them on the gov website? I could be wrong. There not very hot just for a flame picture in the evening.

(I've followed the gov rules for wood burners, distances from walls, size of hearth etc).

Theres a few things that need sorting tbh plasterer didnt use the correct materials for one so I'll be replacing that down the line with hardie backer.

I've got a 30 mm slate hearth on level cement base set on runs of construction adhesive. It's been there no problem with a WB on top for nearly 7 years with no issues.
I'm curious to know, why all the complications with lime and pva?

Cheers for the help, me just over thinking trying to find the one right way to do it. Only reason for lime is I have a bag of it I'm hoping it would help with any movement. The burner is 80kg so it will need to take some weight haha.

Cheers for the helps guys I'll post when it's in.

 

[Rageyboy91]

Shes down, cheers for the help guys. Was a nightmare tbh.

For anyone doing this the advice i would give is I make a wetter mix and super soak and concrete, the concrete was sucking the moisture out of the mortar even after soaking wet.

 

[Rageyboy91]

Hey guys, could anyone recommend a good grout or caulk to fill in the gaps around the edges. Wanted something in a caulking gun size tube.

Cheers

 

[lostinthelight]

You may want to leave a bit of room for expansion around the back if the slab gets warm

 

[Rageyboy91]

You may want to leave a bit of room for expansion around the back if the slab gets warm

I was thinking something flexible, maybe even a type of silicon. Its a abit of a annoying one as it needs something to finish it but like you said I dont want to restrict any expansion. Any product recommendations?