Insulating Solid walls

[Rob]

messagenews: [e-mail]...

snip

No, you - why didn't you claim the prize?!

Rob

[meow2222]

Correct. You've offered us no experiment that demonstrates your belief in widespread rising damp, and no logical reason to believe it either. I've offered 3 experiments that cast great doubt on it, and elementary logic makes it clear that there is more than one cause of damp at skirting board level. Bring us some facts you can substantiate.

NT

[meow2222]

Bricks are porous, the pore sizes vary widely. Simple physics tells us that an injected fluid will follow the path of least resistance, which is via the biggest pores. The idea that injecting something can make a brick waterproof or vapourproof just doesnt fly. Show us some support for your claim, perhaps some evidence. If there is none, I can think of an easy experiment using food dye mixed with the fluid, and the brick sliced up once dried out.

NT

[Stuart Noble]

I'd rather believe that there's a good reason we build houses with damp courses. Flying in the face of 100 years worth of experience might be seen as being a trifle loopy. I've never seen RD but I don't doubt it exists. I've never had smallpox either

[meow2222]

I see, so the existence of a regulation proves its necessity in your eyes? Your logic is loopy.

NT

[Tim Lamb]

In message , The Natural Philosopher writes

Do keep up:-) The Victorian barn is currently having some underpinning/structural pads installed so I can put a steel frame inside. Unfortunately it forms two sides of some new build for which I am struggling to find affordable builders. I think I have got a handle on this now: interstud insulation, plywood exterior and then more Celotex and new block.

Yes. Not Mouse size vents though! I could use eaves vent or rely on warping from the feather edge.

You are not inches from a busy by-way. I'll start in cavity brick and break to 220mm block + insulation behind the boarding.

regards

[Steve Firth]

It comes from "Moisture Movements in render on brick wall" KK Hansen, TA Munch, PS Thorsen, C Villumsen, LC Bentzon; in Research in Building Physics By J. Carmeliet, Hugo S. L. C. Hens, Gerrit Vermeir; Pub Taylor & Francis, 2003 ISBN 90 5809 565 7.

The paper cites the most common pore size in fired bricks as 2000nm.

There may be pores musch larger than 4200nm, but the important factor for wicking is the size of the pores in continuous contact through the matrix of the brick.

[Steve Firth]

It rises to a point where evaporation balances capillary action. That can be a distance several feet to tens of feet, not the "inches" that you referred to.

Mr. know-nothing boasting of being a natural philosopher and shpwing no signs of talent in that field of human experience.

[Stuart Noble]

I can't believe that. I've tried getting water to wick upwards in absorbent materials, and inches would be the scale

[Steve Firth]

I used to regularly run thin layer chromatography plates in which the water phase rises along the plate by capillary action. The plates were about a foot long and the water made it all the way to the end of the plate. These were only run for short periods.

I'm led to conclude that the absorbent materials that you used either permitted evaporation at such a rate that liquid couldn't rise very high or that the pore size in the absorbent material was much larger than you thought.

Besides, you're turning blind eye to the fact that capillary action can (and does) raise water over well over 10metres in trees.

[Dave Liquorice]

Is it so old that it doesn't already have a DPC?

Solid walls are not very good insulators, they have high thermal mass which can help regulate internal temperatures but they have relatively low thermal resistance.

In my view inside is probably the simpler method but with the disadvantage of making the rooms a bit smaller.

[Andy Champ]

Your walls are transpiring? I've heard of green buildings, but that's ridiculous!

Actually it's scary reading NP's very good article. Not only does it contain things I'd forgotten, it also has things in that explain features of the wood that were "just there" when I last studied it...

Andy

[jim]

for others "at the back" my answer was to the following ;-)

jim

[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:

I have direct experience of this in my last house - a 1920s cottage where the walls were mass concrete and no DPC. The site was on the edge of a drained and filled duck pond, according to locals. The lower internal 6" of the front wall was definitely damp - not enough to blow plaster, but not dry. Surrounding the cottage was a concrete path which ran right up to the walls; it was definitely below floor level, by a couple of inches. So, imo, the only place the damp was coming from was underneath the wall, iow, the ground. Oh, the same local who told me about the duck pond also mentioned there were no foundations as such, but the walls were about 20" thick, so I suspect they weren't needed.

[Rob]

There's something that doesn't sound quite right.

Isn't that reference about render? In that case, they mention the higher porosity (at least a factor of 10) of render, and that appears to be one of their points. Also, it's to do with penetrating (largely) horizontal damp through brick, rather than vertical travel. This page is interesting:

It obviously rabidly anti rising damp, but contains some interesting photos (including brick walls in water without dpcs - anyone living near a canal can see similar) and references.

Rob

[meow2222]

- and rain splash and of course condensation Seems the rising damp people always offer that illogic

NT

[The Natural Philosopher]

Ah yes. Rain splash in the middle of a house miles away from any exterior wall is always the obvious reason.

And you get tons of condensation in the middle of a hot summer with the windows wide open don't you?

What's it with you? You are like Hansen, no matter what the evidence is, your Faith triumphs over Reason..

[meow2222]

I dont recall ever saying that applied to interior walls.

not normally. Most houses suffer damp more in winter of course.

strange, i could say exactly the same

NT

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember [e-mail] saying something like:

Nope. The roof overhang ruled out splash the and cottage, being an old thing, was well ventilated.

[RobertL]

On May 2, 6:45=A0pm, [e-mail] (Andrew Gabriel) wrote: > I don't claim any particular expertise here, but a vapour barrier

might it not form on the inner side of the celotex having migrated through the walls from inside the house?

Robert