Chemical DPC re-treatments

[111mart111]

A thought ...

As well established on this forum chemically injected DPCs into older period properties may not have the desired effect and could in some cases make a damp problem even worse.

My question is that if this is the case, why do the chemical DPC companies offer a 20/25 year guarantee on their work done in an older house, and most probably they will get the inevitable call from the owner saying 'get around here, your DPC has failed, please fix it'.

I guess they would then be obligied under the guarantee to do their original treatment again and again until the house owner was satisfied.

Surely this isn't cost effective for the company?

 

[Nemesis]

They don't do the original treatment again and again though.

In the past, many have gone out of business/changed names etc to avoid having to re-do the work.

Mostly they manage to get out of responsibility by various means.

There is a suspicion that the injection isn't what 'works' (for a while) - but the hard 'waterproof' renders etc applied internally.


Read this:
http://periodpropertyshop.co.uk/phpBB2/viewtopic.php?t=4674&highlight=carbide

 

[PC]

Chemcial damp proofing of any building generally relies on a damp proofing system.

i.e the injection of chemicals and the replastering, which as we all know is usually a cement based render and it is the latter that probably causes the biggest problems with damp entrapment.

The former (the liquid injection system) will in most cases in old stone wall's - 'be limited in performance' as clearly it will not (can not) form a continuous horizontal barrier and it is generally accepted that chemical DPC's are are part of the control and not a cure! So why install them?

I am not sure whether the injection of a chemcial dpc would actually make things worse, it is almost certainly the cement render that will cause the problem.

Chemical dpc's in some materials (brickwork) provide some degree of protection but - THATS ASSUMMING THAT THE WALL HAS RISING DAMP IN THE FIRST CASE and thats always the main bone of contention!.

Incidently last week I surveyed a building in Dorset and a local damp proofing company had recommended £6,500 worth of treatments, which prompted further survey by myself. The property had just undergone a full extensive refurbishement with lime plastering and repointing - Grade II.

There was NO visible spoiling, other than to front of chimney (small salt patch) suggested leaving to dry out and monitor.

Main problem was the valuation survey picked up damp and recommended survey by damp proofing company and to implement and necessary works. The RICS Surveyor was aware that the property had been fully refurbished so why didnt he take that into account!!

PC

 

[Nemesis]

The whole thing is an absolute scandal - one which RICS needs to start addressing, as do the mortgage companies...

See Matthew's thread below about his mortgage...


http://periodpropertyshop.co.uk/phpBB2/viewtopic.php?t=6814

 

[NT]

A thought ...

As well established on this forum chemically injected DPCs into older period properties may not have the desired effect and could in some cases make a damp problem even worse.

My question is that if this is the case, why do the chemical DPC companies offer a 20/25 year guarantee on their work done in an older house, and most probably they will get the inevitable call from the owner saying 'get around here, your DPC has failed, please fix it'.

I guess they would then be obligied under the guarantee to do their original treatment again and again until the house owner was satisfied.

Surely this isn't cost effective for the company?

The guarantee is marketing, buyers prefer a 25 yr gtee to a 5yr one. A company can be closed and reopened as another company every so often to avoid any risk of paying out on the guarantees.


NT

 

[Matt Green]

My question is that if this is the case, why do the chemical DPC companies offer a 20/25 year guarantee on their work done in an older house, and most probably they will get the inevitable call from the owner saying 'get around here, your DPC has failed, please fix it'.

The perception of what is guaranteed by the homeowner and what is actually covered differ.

You do not have a guarantee that states your house will not show any signs of dampness in 20yrs. What you have is a guarantee that states that if the wall(s) injected with a chemical damp proof course are accurately tested for dampness within that time they will be found to be dry.

The difference is very important and very lucrative.


Matt Green

 

[Matt Green]

The guarantee is marketing, buyers prefer a 25 yr gtee to a 5yr one. A company can be closed and reopened as another company every so often to avoid any risk of paying out on the guarantees.

NT

As a nod to even-handedness; there are many companies that have been trading for a very long time (the 3 biggest have been trading for over or nearly 50yrs). There is often 3 party gaurentee protection as well.

Making a claim is frighteningly difficult though and usually prohibitively expensive: you have to pay for a copy of the guarantee if you lose it, pay to have the work inspected (refunded if the claim is upheld...) and pay for replastering and redecoration. :x



Matt Green

 

[Nemesis]

Even handedness?

It's bloody daylight robbery! (IMHO of course...)

I quote:

Matt Green
Guest





Posted: Fri 17th Mar, 2006 9:43 Post subject: Re: Types of Damp Proof Course

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"If rising damp is definitely the problem, then I'd go for injection over electro osmosis. I have never seen electro osmosis work. "

Rising damp very rarely ever is the problem though is it? Once high ground levels, gutters and bad rendering have been eliminated- so has the damp problem in 99.9% of cases.

"The main problem, as has been highlighted in previous posts is the replastering. The options offered by UK damp-proofing companies are somewhat limited by their requirement to offer 30-year guarantees on their work. "

These days it's 20 years and the plastering is not included in that gaurentee, just the effectiveness of the DPC. The usual modus operandi when dealing with a guarentee claim is then:

-check that the ground levels have been lowered (as would likely have been mentioned in the report). If not, walk away.

-check the building is well maintained and in a watertight condition (check the small print). If not, walk away

-test the wall with a calcium carbide meter. If it registers less than 5%, walk away proclaiming the wall dry and the injected DPC working. Hope the client doesn't suddenly realise that the wall may never have been damp if such a test had been performed in the first place.

-if it's less than 5% it off to the hygroscopic chambers to show the wall is salt encrusted and sucking water in from the atmosphere. Anything over 3% using the oven balance method and you can walk away.

Now the way has been cleared to blame the plastering which only has a statutory 6 year (?) fit-for-purpose guarentee. Cement-based plasters can usually hold out for that long.

Use breathable finishes and make sure the causes of the water ingress are dealt with. It's the best option for the building, regardless of who happens to own it at this point in time.

Matt Green

 

[NT]

Some of this thread could do with copying to the proto - damp faq.

NT