Take your time with Damp Proof Coursing (DPC)

Damp Proof Coursing (DPC) is such an important aspect of bricklaying and it is something that is so overlooked, given it has the potential to create many ongoing and costly problems.

As practicing Bricklayers and contractors, we have been handed down so much more responsibility and extra work (unpaid also) in installing DPC.   It has to be constructed in a way as to not only stop water penetrating into dwellings, but also to prevent rising damp.  The issue of rising damp is often overlooked and creates huge dramas if not addressed correctly in construction.

It is a known fact that rising damp may penetrate through a concrete slab.  The general thinking is that the concreter would have placed plastic under the slab.  However, if there is a footing under the slab there will not be any plastic.

Now to the corners

Many carpenters have little idea of cutting in corners which leaves gaping holes requiring another piece of dampcourse cut to patch the hole later on.   I am vigilant about this.  Corners, no matter how much we try, have more mortar dropping from them, than on the average straight wall because the bricks are laid from both directions.

This results in significantly more mortar collecting in the cavity at the corners. As Bricklayers we have to be on the lookout, especially when the DPC has not been fitted correctly.

Some builders place the DPC on brick veneers under the wall frame to combat rising damp.  This is not good as the DPC only has a potential of about 30mm under the plate.  Any droppings in the cavity over this will allow water to penetrate under the bottom plate.

It is really important that the DPC has plenty of height.  Rain, pushed by driving wind, can force the water into the cavity through the weep holes, resulting in the water backing up.  If the DPC is not high enough to penetrate under the bottom plate, carpets and such like, as well as rotting skirting and timber work can result.

Keeping the cavity and the weep holes clean is always good policy.

I still believe in putting on a row of ties on top of the first course of bricks laid directly on the DPC.  The ties which can be bent into the holes of the brick are attached to the wall frame, unlike the method in the AS3700 where the DPC is to be sandwiched in mortar.  This never looks tidy as the flashing ends up wavy.

This is also my rule for cavity brickwork.  The damp-proof coursing usually sits up one course higher on the inside skin, so put the wire cavity ties on top of this course (embedding them into the mortar), this gives a much stronger result.

Damp Proof CoursingI am writing this as a Bricklayer who has had to deal with problems in these areas.  Believe you me that it is so much easier to spend a little time with DPC.

Peter Cartwright
Author:   Bricklaying – The Art

For further information on DPC refer to Bricklaying – The Art by Peter Cartwright – The Ultimate Guide to Bricklaying for the Beginner through to the Professional

12 Responses to “Take your time with Damp Proof Coursing (DPC)”

  1. Eoin Lee

    Hello Peter, liked your blog. I think the simple solution to prevent the rising damp problem is to have the proper chemical injection into the bricks.

  2. Kole Denkov

    How far back from surface the face of the brick should be .can you please attach some sketch please

    • BAB

      Hi Kole, Best thing to do would be to speak with the Builder as each builders standard is slightly different. Last time I checked the code Damp Proof had to be showing 3mm past face of brick, but as said earlier, each builders has a slight variation in requirements.

  3. Jan

    My terrace house was built in 1896. I have major rising damp. Cement over the bricks that I’m told I should take off. I’m told I can’t have soak walls as too close to neighbours. The rain turns the walls green, bright green & grey patches of damp. I’m told so many ways to fix I’m at a loss

    • BAB

      Hi Jan, You need to get a brickie in ASAP to have a look at this problem, it does need to be addressed. We will contact you for further info. Cheers.

  4. Mark

    If there is a 2 course step down from the slab on a brick veneer what course should the damp course go on,what are the Australian standards

    • BAB

      Hi Mark, I have sent information directly to your email address. We also recommend you review the Building Code.

  5. Lozzi

    Just got new house built, can not see the dpc, it s brick veneer on waffle pad. Asked builders and the said yes it s there, set back 4 or 5mm in from the front of brick and mortared over. Is this right? I looked and saw it is supposed to be out past brick and no mortar over it,builder said scrape some off and you will see it. Can you let me know please.

    • Ayesha.Dadlani

      Hi Lozzi,
      I have sent information directly to your email address regarding this enquiry. I hope this info helps. Cheers

  6. Chris Hawthorne

    Im having to replace bearers because of no dampcourse. Im installing dampcourse under the bearer. But to make my life easier im wondering if i can staple the dampcourse onto the wood so as to prevent it moving around as i install it. Please instruct.

  7. Steve

    Hi, were in discussions with a builder and planning a new build. We would like to know how to maximise neatness or hide the dampcourse in high traffic areas such as the verandah or alfresco. We’ve seen homes where tiles in alfresco or portico have covered the dampcourse and then been siliconed, but our builder says you need to see the edge of the slab and the protruding dampcourse? Wondering who to talk to about this?

  8. Mathew

    When installing dpc is there law it has to be inserted behind wall wrap/sarking ?


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