Rising damp!

[MIGNAL]

I have a bit of damp on an internal chimney breast. Usual problem, damp plaster, flaking paint, signs of salt deposits.
A bit of research was required on how to deal with the problem. Then I came across this interesting website:

http://www.heritage-house.org/damp.html

Just read the left hand column. Whilst reading it I came to the conclusion that our very own Jacob must have penned it!

 

[Jacob]

So I'm not the only one then!
It's not such a radical view - SPAB will say the same more or less and there has been a lot of research into old building conservation in recent years.
Part of the delusion of the effectiveness of dpc installations is due to the fact that other things are usually being done at the same time e.g. improved heating, insulation, repairs to roofs and rainwater goods etc

What's the situation with your chimney?
The most common cause of damp is lack of ventilation in an unused and blocked chimney - either deliberately blocked or filled with rubble and soot falls. The solution then being obvious - clean the chimney and un-block it, then fix a vent at the bottom and a cowling of some sort at the top.
Second most common is condensation from gas installation - should have lined chimney to keep exhaust gasses warm and faster ascending.
It all depends on the details.

 

[MIGNAL]

The actual chimney stack was taken out long before I moved here. All that remains are two vertical columns that run from the cellar to the roof space. A little odd I know but I guess they took the fronts off for shelf space! Those columns are on a party wall.
Pretty much all the cellar walls are damp, it's just that the worst part in the living room is at the base of those two chimney columns. There are 6 air vents in the two cellars. I've just started putting in a few more to see if it improves things. I doubt that it will be a cure.

 

[Digit]

Whilst some of that is true it must be remembered that Lime mortor would be difficult to use on a cavity type wall.
The reason the UK swung over to cement mortars was two fold, certainty of setting and the structural weakness of Lime mortared walls. Any old bricky will tell you that Cement mortars hold bricks together and that Lime mortars keep them apart.
It's nice to use though.
The picture of the damp above the DPC is typical of 9 inch brickwork exposed to driven rain etc. It soaks into the bricks and spreads, when it reaches the DPC, it stops.

Roy.

 

[bosshogg]

What's the situation with your chimney?
The most common cause of damp is lack of ventilation in an unused and blocked chimney - either deliberately blocked or filled with rubble and soot falls. The solution then being obvious - clean the chimney and un-block it, then fix a vent at the bottom and a cowling of some sort at the top.
Second most common is condensation from gas installation - should have lined chimney to keep exhaust gasses warm and faster ascending.
It all depends on the details.

+1 to that Jacob

We try in these days to outdo nature, unfortunately this seldom works. Buildings that breath, that is to say, allow moisture to come and go as conditions dictate, almost always will outlive any modern building that pro-port to do the opposite. Take the coliseum in Rome, almost two thousand years old, and still no rising damp, just breath-ability...bosshogg

 

[Digit]

And daily I see new builds being rendered with cement mortars BH. But then, have you seen the price of Lime?

Roy.

 

[bosshogg]

And daily I see new builds being rendered with cement mortars BH. But then, have you seen the price of Lime?

Roy.

Yebut, the price is relative to it's volume of production compared to cement, economy of scale and all that. Furthermore in environmental costs lime is soooo much better than cement. Take out all the variables downstream of this and lime becomes more economical in the long run, and not by any short measure. If a wholelife cost study is done on both cement and lime, lime comes out as aprox 20% to the better over cement in co2 out-gassing, absorbs co2 during it's entire life span, i is recyclable (yes folks you heard it here, all lime products, to the best of my knowledge are recyclable i.e. mortar can be reused as mortar, limecrete as limecrete etc. etc.) plus lime renders can cure sick building syndrome, to name just a few of the benefits. Limecrete mixed with hemp shives - "Hempcrete" - can replace common blocks and insulation in one stroke due to the insulating values of these blocks. They have similar load bearing capacities, look almost the same and are lighter addressing the H&S problem of the weight of common concrete blocks. The allowable weight recommendations advised for one man to lift, have fallen considerably over recent years, and with hempcrete block this can be addressed, furthermore they are cheaper then any of the alternatives in whole life costing, something which will probably become part of the building regs before very long...bosshogg

 

[Digit]

For the DIYer BH Lime every time, its ECO advantages over cement are considerable and where it can be used I like to see it used. I've been using it this week and the setting time can be much longer than cement. In my case this limited the number of courses that could be laid in a day.
Developers would not like that, money again.
And yes, you are correct, Lime can be recycled.
What really finished it for general building was the cavity wall, that increased the load on the lower levels and caused Lime to fail apparently.

Roy.

 

[bosshogg]

Whilst some of your assumptions are correct insomuch as time, business and increase in perceived costs, may indeed limit the commercial usage, at this time, that will more than offset in the whole life benefits to be gained. Empirical research was completed, as far as it goes, by Rachel Beven and Tom Woolley of Rachel Beven architects,and presented in their book Hemp Lime Construction, a guide to building with hemp lime composites. One of the things this suggests is the need for ongoing research into the load bearing abilities of the subject matter, but, by enlarge the compressive strength of hempcrete blocks is lower than that of concrete blocks on a quid pro basis. However a new chapter in building technology is unfolding as we speak, and air tightness is rapidly developing into the holy grail of conditions being aspired to in sustainable/eco build targets being set in the overall trade. One of the downfall of brick or block build, is the amount of separate actions required to produce a monolithic mass, and these in turn allow for a rise in failure at the various joints, corners, roof joints etc. with hempcrete and a simple structural timber frame, this need not be the case, foundations, walls, roof and all exogenous cold air actions, can be designed out with a homogeneous approach...sorry to be so long winded, that's me getting back into my academic mode. Heres a link to one of the articles I've mentioned http://opus.bath.ac.uk/16170/1/papers/Paper 123.pdf also it's a condensation paper from the book I mentioned...bosshogg

 

[Digit]

I was speaking of straight Lime sand mortar BH, after all, if you want additives in the past pozzolanic additives were the norm.
Personally I think the future in the UK is timber as you mentioned.
There are a number of straw houses now locally, but strangely a recent planning application for an entirely timber structure like mine was refused!

sorry to be so long winded, that's me getting back into my academic mode.

Don't apologise, IMO the time for a radical reassessment of brick and tile construction is long past.
It's out of print now I believe but a book entitled 'The history of the brick' was much more interesting than the title would suggest.
A local company sells insulation for cavities and lofts made from wool, now I wonder where they get their supplies?! :roll:

Roy.