Plastering Heraklith for a partition wall

[mm289]

Hi all,
been following your discussions and stories for 6 months now since starting in earnest to "repair" our late C18 brick built farmhouse. Figured it is now time to introduce ourselves and ask a few questions
The property is our family home where we have lived for about 6 years and was "restored" in the early '80's including covering everything in portland cement based render and plaster, replacing half the wood windows with uPVC and injecting a chemical DPC! :evil:
The house is actually in very good condition, but isn't "breathing" terribly well and has had a lot of original features played with or spoilt for what seems to be cost or speed reasons. Our main aim is to secure the ongoing strength of the fabric of the building (repointing/repairing walls that are suffering from being "damp prooofed") as well as sympathetically promoting orginal features where possible.
One of the minor projects (and one I can do at this time of year) is repairing/extending an internal partition and door in one of the rooms that was installed in the 80's. Like everything in the house it has been done just by nailing up some plasterboard and painting it, no skim or anything. As we are going to replaster the room in lime having relieved it of the portland I want to plaster the partition as well to match so when I paint (limewash) it is all matching. I also want to make the partition a bit more solid and soundproof.
So, intended spec is a stud type wall using heraklith on both sides sandwiching a layer of Kingspan or similar then plastered in lime.
Couple of questions:
1. Any problems/concerns with the above approach or alternatives you would suggest?
2. Anyone found heraklith at local suppliers as opposed too by the pallet from Skanda?

Thanks in advance and look forward to talking to you all over the coming months.
Cheers, Paul.

 

[MdB]

Hi Paul, welcome to the forum.

I commiserate regarding the cement. I'm currently covered in cement dust having spent the afternoon / evening chiselling it off our old walls. Fortunately, ours isn't stuck at all to the wall so it comes of cleanly.

I think my question for you on the construction of your partition is what exactly are you trying to achieve? If you are trying to use traditional methods, plaster and lath would be the obvious choice. If you want to use modern methods then I would stick to plasterboard. You can either plaster it with the pink stuff or with lime if you use a suitable base layer first. Lime wash will go onto to both I believe (could be wrong on this). Is there any particular reason for wanting to use heraklith which I've not heard of before (which shows you my expertise). Tell us about it.

Sound proofing wise, I wouldn't use Kingspan as although it will do something, I doubt it is as good as a product designed for the job, which may well be cheaper. Again, not an expert on this.

 

[chuckey]

KIngspan has virtually no sound proofing characteristics, use glassfibre/mineral wool/real wool instead. And/or increase the mass of the wall by using double thickness plasterboard.
Frank

 

[Gervase]

Plasterboard :roll:
Heraklith is an excellent substrate for lime plaster and has enough flex when screwed (not nailed) to studwork to preserve the character of a wall - something that plasterboard cannot do. A number of places sell it, and Ty Mawr now does their own brand of Italian wood-wool board, which is almost identical to Heraklith but cheaper and in 2.4 metre lengths rather than 2 metres - a godsend if you're covering studwork at 600mm or 400mm centres as there's far less waste. It's available in 15mm (ideal for your purpose) up to 50mm for external insulation.
Two layers of plastered Heraklith or wood-wool board on its own will have accoustic damping qualities as good as if not better than lath and plaster - though I tend to use either sheepswool or rockwool in the cavity for extra accoustic and thermal insulation. Both are environmentally sounder than Kingspan and less likely to give off fumes.

 

[Moo]

Now that's the sort of information that makes this forum absolutely indispensible. Good old Gervase!

 

[mm289]

Thanks for the replies people, I had seen the Ty Mawr wood/wool boards and wondered if they were the same as Heraklith. Main reason for looking for Heraklith suppliers is I am in Kent and wanted to pick some boards up from somewhere local - any suggestions?

Is there any special advice for plastering these? Normal haired scratch coat, main coat and top coat?

cheers,

Paul.

 

[Gervase]

With Heraklith you can get away with just two coats - haired base at around 5mm thick and finish coat on top of that. Wet it well first because there's quite a bit of suction in the material.
I'm afraid I can't think of anywhere local to Kent - although it might prove economical to see if anyone in northern France stocks it and bring a van-load over.

 

[mm289]

Thanks for the suggestions. Will explore the France option as I am only 26 miles away!!

On the 2 coat plaster approach, would you scratch the base coat or would it be sooth?

Cheers,

 

[Gervase]

Put wavy lines in the base coat with a scratch comb - don't use a devil float or pointy laths as you just want to give a slight key for the finish coat.