Damp course for victorian terraced house

Hi,
A friend is looking to buy a Victorian Terraced house, and it doesn't have a damp course.
After spinning her an elaborate story about having the entire house sliced out of the terrace and lifted up on blocks while a damp course is fitted, I promised to ask around to find out how much she should expect to pay to have a chemical DPC done.
I seem to recall someone else having the chemical DPC, and it requiring a certain amount of replastering to be done after, because the plaster had to be stripped back at the bottom of the wall. Is this normal (or even anything to do with the DPC?)
Any hints, tips gratefully received.
Chris
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Chris Styles wrote:

Unless there are damp problems that you can conclusively attribute to rising damp (which would be unusual), leave well alone, and tell any mortgage lender that you'll go elsewhere if they're not happy with that.
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Stuart Noble wrote:

I think it's almost a given that if they inject a DPC, in order to offer the magic and worthless guarantee which is required to satisfy the lender, it will be required to rip off the bottom metre of plaster back to the brickwork, and replace with Special sand/cement-based plaster. Hell of a mess.

I totally agree with the sentiments but she'll end up in just the same situation with any other mortgage lender (paying an arrangment/valuation fee each time) will the possible exception of a specialist lender who deals in and understands period properties, but are unlikely to be able to match the mortgage deals offered by the big boys.
David
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Chris Styles wrote:

I'm pretty sure that re-plastering would really only be necessary if there was rising damp that had left salt stains in the existing plaster near to floor level.
You don't say whether there is any evidence of rising damp. It is also possible that the vendors have done a quick disguise by using stain blocking paint so a *proper* independent damp survey would be a good idea.
Of course, a damp proofing company might say differently as most of the work and perceived value and thus cost, is the removal of the old plaster and the re-plastering.
Sorry, no idea of cost.
Steve
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On Mon, 29 Oct 2007 12:14:33 -0000, "Chris Styles"

We were quoted £650 by Dampco for two inside walls - one about 7 foot long and one about 4 foot. This included removal and replacement of plaster but not radiators present. On moving into the property, we see no signs of damp at all - dunno what Dampco were detecting but I can't see or fell or smell anything at all, so we have just left it alone..
On my old house, we had the front exterior wall done (15 foot long) and it cost £1000 25 years ago.
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Neither do any in this street in London.

Not actually so silly - I've seen a mechanical damp course inserted by 'sawing the wall in half'. And it's likely to work rather better than a chemical one which is a con.

Well, yes. If you have damp showing - for whatever reason - removing the old plaster and replacing it with waterproof skim plus plaster will stop the damp showing again - at that spot.

Do a Google and you'll find plenty advice. Suffice it to say true rising damp is extremely rare - otherwise those houses would have been built with one in the first place. Most causes of actual damp are cause by water penetration - patios etc added afterwards not draining water away from the walls.
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Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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a
I
have
to
anything
The Building Research Establishment did extensive tests, to try to detect rising damp, by standing various building materials in water for prolonged periods. They concluded that damp does not rise more than, at most, a few inches, which implies that the DPC is entirely superfluous. Good ventilation is far more important for avoiding damp problems.
Colin Bignell
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nightjar wrote:

Do you have a link for this study Colin?
As said, its a waste of time. The usual solution is to get a competent specialist to put in writing that such treatment is not appropriate and not needed, then BSs will usually say ok to that.
These folk http://periodpropertyshop.co.uk/phpBB2/viewforum.php?f=1 could probably point you to someone capable of the job.
NT
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snipped-for-privacy@care2.com wrote:

>

IIRC it was one that Jeff Howell was involved in or at least reported in some depth - there seems to be much less info about it on his site now, but I think the graphs in this link refer to the same study:
http://www.askjeff.co.uk/content.php?id=3
David
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Lobster wrote:

Thanks - I just wish the BRE study were online somewhere
NT
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nightjar <cpb@ wrote:

One wonders why damp courses ever became standard practice
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Stuart Noble wrote:

Indeed.
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nightjar <cpb@ wrote:

Well it made about a foot in my old house up 18th century porous brick.
Quite enough to rot all the floor timbers and blow all the plaster above the skirting.

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And just how old were the timbers and plaster? And if it were rising damp due to no damp course would have caused these problems many times in the house's life?
Of course if you concrete round the outside of a house where there used to be drainage you can often get damp penetrating through porous bricks, etc. But that's not rising damp.
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*Why is the word abbreviation so long? *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Dave Plowman (News) wrote:

Timbers? probbly 200 years
Plaster? looked like 70's
And if it were rising damp

Indeed. It obviously had.
Some patching had improved it, other patching had trapped rot inside.
Plastering over what had been brick chimneys sealed its fate.

Er..concrete round a house does not affect damp being sucked up in the middle of it by the chimney.
When w finally took it apart, there was a small pond under the floor and the chimney stood in the middle of it.
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...

The theortical lift in a glass tube of 0.2mm diameter, which should be more effective at producing a straight lift from capillary action than the variable size passageways in a brick, is 14cm, although the theoritcal lift is not normally achieved. That suggests that either you have a reduced force of gravity in your house, or a higher than normal surface tension in your water, or it was not rising damp.
Colin Bignell
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wrote:
message

Or that the typical hole size in the brick is less than 0.2mm? (I would have expected the lift height to be roughly inversely proportional to the hole size for "small but not atomic" sizes.)
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wrote:

There are some big wooden things growing in my garden which suggest that capillary action can be used to raise water a lot higher than 14 inches ...
Ian
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Water does not rise in trees solely by capillary action, I'm afraid.
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and presumptuous desire for a second one."
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Huge wrote:

Maybe its the same thing n walls then ;-)
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