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Help! Apparently my house has no DPC and I need to make a decision quickly!

(13 Posts)
BasinHaircut Tue 01-Dec-15 12:37:05

The re-rendering of our house has finally started, after a structural set back which has meant that whilst this should have been done in September, its getting done in December.

Anyway, im at work today and the renderer has just called me and said that in hacking off all of the old and very damaged render, he cant find a DPC. So firstly he cannot find the correct level to put the lip that ususally sits just above the DPC (old one was far too high) and secondly, he is saying that if we continue without a DPC we could be setting ourselves up for lots of problems in the future.

Our house is 1930s built and im assuming should have a DPC? We have some damp but its all in places where the render is damaged and that includes on the bay upstairs. It is not rising damp. We did get a very wet wall in the downstairs bay during the week that it rained really hard in the summer, and the renderer (and the buidler I had in at the time) both agreed that it looked very much like bridging damp and wasnt coming up through the DPC.

Now im not sure what to do. If we dont have a DPC, is it really necessary to inject one? or even the correct course of action? The renderer has suggested alternatives including something to do with bitumen, and also spraying the render to make it more waterproof or something, but this was framed as very 'do you intend to live here long term or is it a stop-gap'?

I want to do it right but ive heard that the injectable DPC isnt worth it. Im going to have a chat with my neighbours to see if they have any knowledge of their own DPC but ive chatted to my neighbout about whats going on a few times (had to get consent to access thier garden to render side of extension) and he has said nothing.

Any advice greatfully recieved!

bilbodog Tue 01-Dec-15 13:50:55

I've had a quick google - there is a lot of info out there and differing opinions. A 1930s house would normally have one but older properties not. You see lots of older properties with rendering so if there is no dpc then they must just decide where to render to. Might be wise to see if you can get any other opinions. Damp companies will always suggest chemical injection but there is a lot of evidence now that this is a waste of time. Hope you manage to get it sorted.

PigletJohn Tue 01-Dec-15 13:57:47

I would have expected a 1930's house to have a DPC. What county are you in? Are you near a railway station? In parts of Staffs and Leics especially, where they make engineering bricks, and near railways where they could economically be transported, a few courses of dark red or dark blue glossy bricks might be used at ground level. Away from the brick areas they would be found in larger or more expensive houses, and in railway, canal or industrial buildings .

Have a look at other nearby houses of similar age. I would expect to see an extra-thick mortar joint, and a think black line, two courses above where ground level used to be when the house was built. Very often the ground level is raised with paving, patios and flowerbeds and covers the dpm. Have a look under the front and back doors.

Have you got a cellar?

Unless you find out more, ask him to put the drip bead nine inches above ground level.

BasinHaircut Tue 01-Dec-15 15:08:06

Thank you both for responding!

I have also been googling and someone suggested taking up a floorboard inside and seeing if the DPC is visible from the other side of the wall. We can easily do this tonight so that is my first job when i get home from work! Never would have thought of that.

piglet im in east London/Essex and yes near a railway (well, tube) line. No cellar. Would that mean that A DPC wouldnt have been necessary if they used engineering bricks?

If we cant find a DPC should we be using a bitumous paint on just the exposed brick below the drip bead?

At the moment there is (or was until they took it off today) a sort of base board round the bottom of the house which i guess might have been protecting the bottom couple of rows of bricks from water so now thats gone do we need to do soemthig else? or should it also be rendered?

I really wasnt expecting this one. We appear to have bought the money pit!

PigletJohn Tue 01-Dec-15 15:46:16

don't use bituminous paint on brickwork. People think it stops water getting in. In fact, water still soaks into the wall from underneath, and paint stops it from evaporating off the bricks where exposed to air.

The boards you mention may have been ornamental.

You are not supposed to render or cover the base of a brick wall with a plinth as it prevents evaporation and encourages capillary movement of water.

If you are lucky enough to have engineering bricks, they will act as a dpc.

IIRC the overground tube, on the Snaresbrook line, was open quite early with small steam trains, and goods such as coal and building materials were delivered along it. You still find old goods yards nearby. Shiny red bricks were used in some cuttings and bridges. The Wanstead leg was built, but not opened, before WW2.

BasinHaircut Tue 01-Dec-15 17:47:47

Thanks again piglet, what do you do at the bottom then? Just leave it?

PigletJohn Tue 01-Dec-15 18:00:12

yes, but do your search for a buried dpc first. Look at other similar houses.

Often you will see the brick colour is darker below the DPC (damp bricks) that above, and sometimes you see efflorescence which stops sharply at dpc level. It will have been two courses above where ground level was when the house was built, which may be quite different to where it is now.

BasinHaircut Tue 01-Dec-15 19:50:06

Right well the good news is I have a DPC. Lifted the floorboard and it's clearly visible.

The bad news is that it's now under the block paved driveway and side path!

What a nightmare!

DickDewy Tue 01-Dec-15 19:55:04

I too would be surprised if a house this age has no DPC. What often happens is the outside ground level changes for myriad reasons and the DPC is breached.

DickDewy Tue 01-Dec-15 19:55:27

Just saw your last post - ignore me!

PigletJohn Tue 01-Dec-15 20:14:11

As expected. The person who laid the pathway and drive was an ignorant buffoon. Very common. There are lots of buffoons about.

You will have to lift the edge of the paving, dig a trench to expose the dpc, line it with landcape fabric, fill the trench with cobbles or pebbles (not sand or gravel). You are constructing a French Drain (q.v.)

A small builder or competent drive-layer will know what to do. If the person doing the rendering seems to be a person who works to good quality, he will understand and will know some builders of equal quality.

If you are a burly gardener you can do it yourself.

BasinHaircut Tue 01-Dec-15 21:21:52

Yes I agree piglet! What buffoons.

DH is keen to have a go at removing the course of blocks that need to be removed and what you suggest sounds easy enough for us to hopefully do ourselves. Will be googling French drains later!

BasinHaircut Wed 02-Dec-15 15:43:53

Oh dear! Renderer wants to come round for a meeting tonight as apparently he has never seen anything like the state of the existing render on our house. He has basically said that it is completely soaked, from the bottom to the top and so his original quote is 'out the window'.

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