Lime ceiling follow up

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JessThePlasterer

Queen Jess Elizabeth I
Ooooh it’s like “question time with @vfr12
Aaaand we have a lovely audience tonight ladies and gentleman! He’ll be here all week !

(Really enjoyed reading this thread)
 

vfr12

MOTORC*NT
Weirdly enough I'll be doing almost the exact same thing as Xeres at some point in the new year. Well, in a mid rather than end terrace and with the back of the house needing a new render too. Not too far from Lancaster either, small world...

My initial guess was to go 100mm thick with external render at the back, then 25mm internally. Then just 100mm internally at the front, is that ridiculous?

For the internal without external contact I didn't realise that Bauwer light would be needed, what's the need for an insulated plaster on internal walls? It's already going to be a decent sized job, potentially the whole house 110m2 of floor space maybe 300m2 of wall space (at a guesstimate), I was hoping for something a bit cheaper for the internal walls without external contact!

Apologies for sniping into this thread!
And yes, 100mm internal is overkill. 25-45 is plenty.
 

malk

New Member
And yes, 100mm internal is overkill. 25-45 is plenty.

Cheers for this. To confirm though:

For internal walls, say from the front room to the back room downstairs, I'd expect the whole floor to be more or less the same temperature so it doesn't matter if the walls conduct heat right? For the internal walls between this and the neighbours houses some insulation would be useful but, typically, the temperature gradient would be lower so it's less important. Especially if they're rich boomers who leave the heating on all the time, I'd be better off nicking their heat through the walls then!

For the thickness, I'd thought 100mm internal at the front as there's no external insulation there. It's just to get the u value down based on Bauwer's calculator. Aiming for 0.7 needs 70mm plus. Is that just a case of whether I think it's worth the extra install cost/hassle for the extra insulation? I.e. from your perspective it doesn't really matter if it is 25 or 100 or does it make it more difficult in general to put on?

Thanks again!
 

vfr12

MOTORC*NT
For internal walls in your house that will be heated from both sides 25mm is ok.
100 mm definitely will give you that number and I will recommend it if it was external with direct exposure to the elements. Internal I think 45 is enough. You’ll also add between 7-10mm after that so your number will be higher.
And in most cases to do 100mm around the house you need to break the bank.
 

zombie

Private Member
Cheers for this. To confirm though:

For internal walls, say from the front room to the back room downstairs, I'd expect the whole floor to be more or less the same temperature so it doesn't matter if the walls conduct heat right? For the internal walls between this and the neighbours houses some insulation would be useful but, typically, the temperature gradient would be lower so it's less important. Especially if they're rich boomers who leave the heating on all the time, I'd be better off nicking their heat through the walls then!

For the thickness, I'd thought 100mm internal at the front as there's no external insulation there. It's just to get the u value down based on Bauwer's calculator. Aiming for 0.7 needs 70mm plus. Is that just a case of whether I think it's worth the extra install cost/hassle for the extra insulation? I.e. from your perspective it doesn't really matter if it is 25 or 100 or does it make it more difficult in general to put on?

Thanks again!

I mean this in the nicest possible way be cheaper/more cost effective to move house!
 

johna

New Member
If you use hot mix, there is a chance that some of the quicklime will not be fully slaked on mixing. Those granules can expand over time, causing blistering and cracks. And when I say chance, assume that this is more likely to happen than not. It's an age old problem.

"Limes which are unsuitable for plaster work, known as hot limes, and which, when plasterers are obliged to use, must be slaked for a period of - not three weeks, but more - nearly three months before using, and are then not quite safe from blistering, are the limes mostly used for building purposes".

Plastering, plain and simple. https://archive.org/details/plasteringplaind00mill/page/42
 
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