Insulating Solid walls

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember The Natural Philosopher saying something like:

It would tend to even out I believe. I don't have any figures, but I've noticed thick-walled houses, if decently draught-free and properly DGd are definitely more temperature stable than thin-wall modern build. Outside insulation would even out the temperature swings even more and lead to less fuel being used as top-up heating. In my own situation, I plan to install outside insulation to 10" thick solid concrete walls and avoid interior disruption. This, allied with UFH, should provide a decent cosiness.

[PCPaul]

I don't know about anybody else, but if I work out how much I have to pay for every square foot of internal space, then figure out how much of it I'd lose with 10" of internal insulation, it would take a *lot* of extra heating to make up the difference.

External is the only way that makes sense, unless you have far too much room in your house at present. Not a problem I've ever been faced with...

[John Rumm]

From time to time, certainly...

[The Natural Philosopher]

Well the figures suggest it doesn't even out. If your target is say 19C for the evening period, you will on average be warmer outside those periods than if the house was a insulated egg carton. The heatloss will be more, on average.

Here, with 24x7 occupancy, the high thermal mass suits our lifestyle.

[meow2222]

are you telling us you have enough experience to know the mixes used were too sandy in a signifcant percentage of houses?

which tells us nothing. We know mortar fails in the end, that doesnt tell us if the mix was too high in sand

Thing about lime mortar is its both soft and very slow setting, which both hinder construction speed. Mixing it too sandy only makes it worse, slowing the build project even further. I cant see many builders doing that to save a fiver in lime.

I dont have enough experience personally, but have heard from folk that do that its not a problem in practice.

NT

[meow2222]

why did you analyse these mortars?

NT

[meow2222]

I dont recall claiming it doesnt exist, merely that nearly all cases of damp at the base of walls weren't rising damp.

This is all too familiar. If you'd done your reading you'd have known that the BRE experiment shows that it does exist.

NT

[meow2222]

I've not come across that. The main issues with pozzolan are:

1. it needs to be mixed dry and kept dry until use. This is not very compatible with the usual site practice at the time of mixing all the mortar required on site in one go at the beginning.
2. It needs to be ground very fine to work. Thats not something one can do on site, so its more cost to put it in
3. It needs prolonged mixing times in the dry phase to work, again translating to a lot more labour, bearing in mind there were no electric cement mixers
4. It sets as quickly as cement, resulting in wastage.

In short, pozzolan wasnt normally used in housebuilding for all these reasons. I couldnt possibly rule it out from all builds, but there were several practical reasons to not use it.

NT

[meow2222]

unless I'm mistaken thats normally due to mortar failure over a century or so. Repointing only usually replaces the outer layer. I'm not convinced it means the original mortar was almost all sand.

... and an unstable wall that goes very wrong very quickly.

NT

[meow2222]

designs

bear in mind that wall stability was a perennial probem with lime built walls. The lime was so slow to set that building progress was hindered by poor wall stability due to wet unset mortar. Saving a few pennies on lime would make the situation much worse, it just wasnt worth it. In fact interior plaster was often overly fat on lime, economising on lime just wasnt usual practice.

NT