DPC

[dabravokid]

Hi all,

When we bought our house the survey mentioned that we should have a DPC installed as there was some damp detected on the outside facing walls. When we had builder round they all quote massive amounts of money and said its not worth it if your not going to live in the house for the rest of your life as its not that bad. They all mentioned installing a pressurised DPC and then replaceing the internal plaster. I have since read about using non-pressurised DPC as a DIY fix. Could anybody shed some light on where I can get this product and tools and if its any good.

Thanks in advance.

 

[Frederick]

There are a number of non-pressurised DPC systems on the market, most of which take the form of a damp-proofing cream which is injected in to holes drilled in the mortar course using a mastic gun.

Although, several of these damp-proofing creams are BBA-approved, the only one that I would recommend is Dryzone which is the only version on the market with a high silicone content (over 60%). I have been given samples of other damp-proofing creams that are cheaper, but they do not spread as well (I have done simple tests using bits of old Victoran mortar hacked off old bricks). I expect that the other systems work well enough in most situations, but I wouldn't want to risk backing them with a 20-year guarantee (which I have to do on most damp jobs I carry out). As with everything in life it's question of "you get what you pay for."

Obviously, you will have to replace the plaster with whatever damp-proofing system you decide to use - which is a bit of a pain in the **** - another good reason for using a quality system in the first place.

Another option that you might consider is to cover the wall with a "plaster membrane" such as Newlath. If the wall is very thick, this option can work out cheaper, but it really just covers up the problem.

 

[Deluks]

Hi all,

When we bought our house the survey mentioned that we should have a DPC installed as there was some damp detected on the outside facing walls. When we had builder round they all quote massive amounts of money and said its not worth it if your not going to live in the house for the rest of your life as its not that bad. They all mentioned installing a pressurised DPC and then replaceing the internal plaster. I have since read about using non-pressurised DPC as a DIY fix. Could anybody shed some light on where I can get this product and tools and if its any good.

Thanks in advance.

Try here: http://www.hss.com/g/50332/Damp_Proof_Injection_Unit.html

I've no idea how to use it though, but can't be rocket science.

 

[masona]

Best to find out what is causing the damp in the first place instead of a temporary solution with chemicals which I have no time for as it's a waste of money.

 

[Frederick]

It's definitely a good idea to check what is causing the damp in the first place. But if the problem is indeed down to a failed DPC, chemical injection (pressurised or non-pressurised) is a hell of a lot less disruptive than putting a new physical DPC in - which is the only other method that I have found to be effective in over 30 years building and restoring houses.

 

[masona]

I can see where you're coming from but doesn't the damp wall have to be bone-dry first before any treatment?

 

[Frederick]

It depends on the brand and type of treatment being used. Most modern treatments do not contain solvents and actually spread better in damp walls.

In the past chemical injections used to be solvent-based and these systems did indeed spread better in dry walls. For this reason some people still say that they are a better choice in situations where a dry wall is being treated - more common than you may think - e.g. where someone has built a new extension and forgotten to include a DPC. I even heard of one example where the majority of a housing estate had been built before Building Control noticed that none of the houses had DPCs!