Damp proof course

JonathanRyan

JonathanRyan

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So I need to replace the DPC on a house.

I've had an estimate from the damp specialist who diagnosed the problem but he's a bit toppy on his other stuff and I can't remember ever accepting a single quote on a job.

What kind of person can do this for me? Is it a job that a decent builder could do or do I need a specialist? Is there a tender site for such people? I've used these before for roofing and general building work.
 
Very interesting read - thanks.

Here's the situation.....the house was built in the 50s. At some point in the 80s a "building" firm (who may have arrived on horseback and carried 6 shooters) built 2 extensions - one front and one back. At the front there's "bituminised felt" DPC but those cunning builders have built some walls that go above it. At the back they have built a charming little patio with the slabs level with the top of the DPC so any rain splash will handily go into the walls above the DPC.

Had a RICS chap out and he said "blimey, you need an expert - get somebody from the PCA. Had a chap from the PCA out and he told me the above and suggested I pay him for a new chemical DPC.

But now I'm confused ;) I remember the pain and cost of the first property I ever bought where we had to pack up everything we owned, move in with friends and let people hack off the plaster for a couple of weeks. Also, expensive. I'm hoping to catch it before then. But now I type this post I start to think that if the damage was done in the 80s then it's either too late or fine......
 
So why not change the patio?
It would be a damn sight cheaper and less upheaval.

Is there also a problem at the front?
 
kendo1 said:
So why not change the patio?
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A very good point. I guess I could lift the front row of slabs, dig a small trench and chuck some gravel in. Given the "quality" of the builders I'd be surprised if that were hard ;)

There are signs of damp at both the front and back. Nothing serious yet but then I haven't seen the property in weeks and it's been raining solidly since then.
 
Check the guttering and brickwork too.

Is it left unheated and unoccupied?
 
I'm assuming the damp is basically at floor level inside then?
 
srichards said:
I'm assuming the damp is basically at floor level inside then?
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That's correct.

High meter readings at the front at floor level and above. At back walls are lined with some magic ant damp meter paper but expert suspects similar story to front.
 
JonathanRyan said:
I guess I could lift the front row of slabs, dig a small trench and chuck some gravel in.
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The easiest and cheapest option :)
Sorry to say the obvious, make sure if you do this that the water is directed away from the house to a soak-away.
There are all sorts of ways of doing it.

I've no suggestions for the front.
 
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JonathanRyan said:
That's correct.

High meter readings at the front at floor level and above. At back walls are lined with some magic ant damp meter paper but expert suspects similar story to front.
Click to expand...

Consistent across the whole width of the wall?

There are a few sites that organise finding decent contractors. I'd try via one of those. Get a couple more quotes and go with whoever seems to know the most and is easiest answering questions.
 
Threads like these are the one of the best reasons why we need an OOF section. Please take note delete button happy mods! ;)
 
srichards said:
Consistent across the whole width of the wall?
Click to expand...

I'm not sure. I don't have access to the property (it's with the lawyers ATM) but the damp report makes me suspect that they breached the DPC in 2 distinct areas and that this will give damp in 2 separate rooms.

I guess my basic question goes back to should I be looking to hire a damp expert or will a general builder be able to handle it?
 
DorsetDude said:
Threads like these are the one of the best reasons why we need an OOF section. Please take note delete button happy mods! ;)
Click to expand...

:)

I'm always amazed at the breadth of knowledge of the people here. And very grateful that people take the time to share that knowledge.
 
JonathanRyan said:
I guess my basic question goes back to should I be looking to hire a damp expert or will a general builder be able to handle it?
Click to expand...
Depends on the builder!
 
Jonathan, it has been a while since I was last involved in this type of thing. Not sure if this will help but here goes ...

Damp from a breached DPC is fairly straightforward to diagnose, it is often referred to as rising damp, basically as it rises from the ground upwards, it usually leaves a hills and valley pattern on the affected walls as well, but the peaks rarely if ever reach 1 metre off the ground as that is the limit of the effects of osmosis. If the damp is higher than that, or doesn't have the hills and valley shape then it is likely that the damp is coming in from other sources, which unfortunately can be many from a breached cavity, to a badly fitted window, broken tiles etc.

The main remedy for fixing a knackered dpc used to be nasty volatile chemicals that were injected into the bricks and your memory of plaster being hacked off is correct. There are newer chemicals now that get injected into the mortar between the bricks which don't smell nor are they carcinogenic. Not sure of plaster needs removing, though I would expect it would, sorry to say. If the ground floor is solid (i.e. concrete) make sure that the plaster finishes 25mm above the floor too. The modern chemicals are easy to use, so much so any competent DIYer should be able to use them.

It is also important to make sure nothing is piled up against the wall forming a bridge across the dpc, i.e. if a pile of earth against the way goes over the dpc then that can be a major cause of damp. The dpc should be at least 150mm above the ground level outside too, so that patio may nee d to be removed and relaid. If the walls outside are rendered then make sure the render is sound and that there is a gap between the bottom of the render and ground level and that a drip strip has been fitted along the bottom edge of the render, it is amazing how many houses have render all the way to ground level!
 
Thanks Paul. Very useful.

With some pointers from you I've done some Googling and to my amazement found that I might even be able to do this myself. I'm assuming you mean something similar to this - http://www.permagard.co.uk/damp-proofing-cream.html - would you mind casting an expert eye over that page to make sure it's a decent product? It seems to have the right approvals.

Well, I can drill holes and use a caulking gun ;) I can also hack plaster off. I'd need to hire a plasterer to make good but they aren't very expensive. Thanks. I'll look further, but it looks like I might be able to save quite a few quid on a job they quoted at just over £1K (without plastering).
 
Is it prudent to have some sort of 'Guarantee' for damp-proofing work carried out ... e.g. in case of selling the house and 'proving' the work done?
 
gramps said:
Is it prudent to have some sort of 'Guarantee' for damp-proofing work carried out ... e.g. in case of selling the house and 'proving' the work done?
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Possibly. But they want to actually charge me for the guarantee. Yes, I was shocked as well.

Oh and charge me an admin fee on top.
 
Also, I do understand the irony here. I mean, I seem to spend part of every day explaining to people why they shouldn't do their own photography........ :)
 
JonathanRyan said:
Thanks Paul. Very useful.

With some pointers from you I've done some Googling and to my amazement found that I might even be able to do this myself. I'm assuming you mean something similar to this - http://www.permagard.co.uk/damp-proofing-cream.html - would you mind casting an expert eye over that page to make sure it's a decent product? It seems to have the right approvals.

Well, I can drill holes and use a caulking gun ;) I can also hack plaster off. I'd need to hire a plasterer to make good but they aren't very expensive. Thanks. I'll look further, but it looks like I might be able to save quite a few quid on a job they quoted at just over £1K (without plastering).
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Yep, that's the right stuff. If you decide to do this yourself use a depth gauge on your drill and do NOT use a hammer action or percussion action as it can blow the mortar out (and I know many will disagree with me, but I've renovated a few hold houses in the past ....). Sorry if I'm teaching Granny to suck eggs btw ..

The one thing I'm crap at is plastering, I can get plastered with the best, but putting plaster on a wall - useless!
 
I can jump in again!
Don't skimp when paying for drill bits. Good drill bits cut fast and keep on doing so.
I've found that, for masonry, DeWalt are excellent for durability and cutting ease.
Cheap drill bits are best put in the bin. (I'd class Bosch as cheap but they cost the same as DeWalt)
Cheapest place normally is Screwfix.
For really hard materials I use Marcrist drill bits, but they cost about £30 each.
 
All good advice here you will only get the same no matter how many biulders you get round. I have used the cream dpc on quite a few occassions and it works a treat, also plastered (as thats what I am) after with sand and cement plus water proofer.
I don't usually do injection damp proofs as a rule but, you know how it is, customers whom you have worked for over the years and have got the odd wall with damp showing.They find themselves stuck with whom to aproach and don't want to get ripped off and they are happy/comfortable with your work so they ask and ask and ask etc etc.
I usually tell them to get in an expert in whom does the relevent tests and see what they say. I can't issue a guarentee hence not getting involved and over the years you see so many problems with damp coming back through. So it's up to the customer but like I say I have done quite a few and they have all been solved with this method. (I used Wykamol) but there are many.

Good Luck.
Gaz
 
JonathanRyan said:
Since it's saving me about £900 I reckon I can afford a good drill bit :)

Something like this? http://www.screwfix.com/p/dewalt-12-160mm-extreme-2-sds-plus-masonry-bit/48196 (I have an SDS drill - a bit like this with the hammer turned off?) I know I'll need to check the length.
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Yep, though I tend to use standard rather than SDS.
http://www.screwfix.com/p/dewalt-12-x-150mm-extreme-2-masonry-drill-bit/43444
(looks like they've come down in price- I'll have to buy some!)

I use Hitachi 18v drill/drivers mostly which get through 99% of what I encounter.
Very light for constant use. I don't often have to use my SDS- it's the drill bit that makes the difference.
 
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