Damp proof course

cornwalltigger

We've had 4 quotes to do some damp proofing in our dining room (3 walls need treating). Its not a big room (sorry I don't have the dimensions) but its a Victorian house so the ceilings are about 2.6m high.

I should probably say at this point that we had an independent surveyor come out and diagnose the rising damp rather than relying on a damp proof company.

Three of the quotes fall in the £1500-£2000 range, but the fourth is only £950. He is using the Dryzone system, will hack off and re-plaster up to 1.2m and then skim up to the ceiling and skim the ceiling as well. He will provide a 10 year guarantee and whilst not a damp specialist is willing to provide references of damp work he has done in the past.

Obviously I don't want to spend extra money unnecessarily, but should I be wary of a quote that is so much lower than the others? Or does this seem like a reasonable price?

Thanks!

Oh PS I'm in Bristol if that makes a difference?

Thunderbird_2

Hi

I know it is not answering your question. When you say an independent surveyor, do you mean the same guy who did the structural survey? Or is it someone you looked up because the structural surveyor recommended you do so?

How many external walls? Was the house empty? Did you just buy it? How old is the house? Before 1880?

I am bit sceptical when it comes to these injected stuff.

Thank you.

cornwalltigger

Hi,

We had a homebuyer report when we were buying the house who found evidence of damp. We then got a damp surveyor in (at a cost of £50 as I didnt need a full written report just a diagnosis and recommendation) to assess it. He doesnt sell any products, he only conducts the surveys and writes a report.

He diagnosed rising damp. I was unsure about whether rising damp was 'real' but he assured me that it is and recommended a chemical DPC. As he was independent and not interested in selling me any products I thought he would know his stuff and advise me correctly.

The dining room has 2 internal walls to other rooms downstairs, 1 party wall (its a mid terrace) and what used to be the external wall, but which is now an archway into the kitchen extension.

The house wasn't empty when we bought it (in February). The dining room had carpet down which has now come up and the floorboards stripped. I marked a tide line on the wall at at that point (March) but the damp has risen above that line in the intervening months.

The house was built in 1900, and the room in question has a suspended timber floor, built on essentially dirt (I'm so technical I know!)

When we stripped the wallpaper in the living room it had modern plaster about halfway up which someone advised probably meant a DPC had been put in that room. The only wall in the dining room which isnt affected is the wall it shares with the living room (which isnt damp) so I assumed that any DPC that had been put in had done its job in the living room and so something similar in the dining room would be required. I don't have anything more concrete to confirm a DPC was installed in the living room however, such as a guarentee.

Knowing nothing about these things makes it very difficult to know what the right course of action is and leaves me in the hands of 'expert' advice.

If you don't mind me asking Thunderbird, why are you skeptical of chemical DPCs? because you're skeptical of their effectiveness or skeptical of the existence of rising damp at all?

In which case I can't fathom how 3 of our walls would all be affected?

Thunderbird_2

Thank you for your reply.

I am skeptical because of the application. The principle is valid. you inject silicone type of thing and that should diffuse and form a level of impervious line, which prevents rising damp. This is in theory.

In practice, more than often, the amount injected in each hole is not enough to meet the amount from the next hole and so on. Also, with the way the wall are re-plastered, it is very difficult to be sure that the damp proofing is working and the bricks are dry.

A solid wall will need, on average, a month for each inch to dry AFTER the rising damp is solved. However, it is very difficult to wait this long unless you are doing a major refurbishment on an empty house. Hence, the tanking technique damp proofing companies use, which essentially stopping the damp from the bricks to show through your paint. And that is why the guarantee is linked to the re-plastering job done by themselves.

Now, you mentioned that there is new plaster (pink?) under the wall paper. Am I right in assuming that the independent surveyor did not see it as it was covered by wall paper?

Pink plaster is unable to tolerate any moisture from condensation. Unlike the old plaster (lime). I am guessing the wall has been injected before (can you remove one skirting board and have a look if there are drill holes indicating previous DPC injected?)

This leads me to another thing about the chemical DPC. Physical DPC, whether it is the original bitumen or new membrane, is usually installed BELOW the wooden joists level of the floor. However, most chemical DPC is injected ABOVE the floor joists, just behind the skirting boards. In my opinion, this is a major issue. Because you want the DPC to stop rising damp to reach the wooden and cause rot, not ABOVE the wood to stop the paint flaking.

I would lift one of the floor boards (I know you have just sanded them and varnished them!) and have a look with a torch light and try to see if there is an original bitumen damp course installed when the house was build. look around 2-3 courses below the joist. You might see nice looking bricks immediately below the floor and then there is a cut off line, after which, bricks start to look pale with salt formation on them, just a gues. Your house was build 20 years after the law has changed and required all new builds to have a damp course, so I expect yours to have one already.

Rising damp does exist, but it is over diagnosed.

What is the floor of the new extension? Concrete or suspended timber?

[Deleted User]

cornwalltigger wrote: »

We've had 4 quotes to do some damp proofing in our dining room (3 walls need treating). Its not a big room (sorry I don't have the dimensions) but its a Victorian house so the ceilings are about 2.6m high.

I should probably say at this point that we had an independent surveyor come out and diagnose the rising damp rather than relying on a damp proof company.

Three of the quotes fall in the £1500-£2000 range, but the fourth is only £950. He is using the Dryzone system, will hack off and re-plaster up to 1.2m and then skim up to the ceiling and skim the ceiling as well. He will provide a 10 year guarantee and whilst not a damp specialist is willing to provide references of damp work he has done in the past.

Obviously I don't want to spend extra money unnecessarily, but should I be wary of a quote that is so much lower than the others? Or does this seem like a reasonable price?

Thanks!

Oh PS I'm in Bristol if that makes a difference?

I'm in a similar situation with a similar house and have just been quoted £950 EX VAT for the work you described by Peter Cox Ltd.

It seems reasonable enough to me, although my issues were from penetrating damp over 10 years - my surveyor said there's no evidence of rising damp but seeing as a lot of plaster was stripped out, he suggested it would be a sensible precaution to put in a DPC.

hotpot1000

I bought a house with visible damp inside one room, external & internal walls, the room being next to a garage extension without a roof for many years.

I had a builder inject some dryzone damp cream I bought off ebay, taking the skirting boards off, injecting and replacing skirts. It didnt cost much, we did it double recommended application to be sure.
any diy person could do it themselves, detailed instructions are available online.


http://www.ebay.co.uk/itm/2-DRYZONE-DPC-DAMP-PROOFING-CREAM-310ml-TUBE-WITH-FREE-FLEXIBLE-EXTENSION-NOZZLE-/290803328686?pt=LH_DefaultDomain_3&hash=item43b53aa6ae