Home

 About Me:

Joe Malone, the author of this building defect analysis site, runs a Chartered Building Consultancy and is a CIOB Chartered Builder, a Chartered building engineer, a degree qualified building surveyor, a visiting University guest lecturer  and a published technical writer.  He regularly gives CPD talks across the UK for The Royal Institute of Chartered Surveyors (RICS), and the Chartered Institute of Building (CIOB). 
Our business, Malone Associates Ltd,  has a strong specialism in building defect analysis and building pathology  and as part of  our academic commitment, we maintain this blog to help further some advancement in our understanding of why buildings fail. 

 

logo_abe

 

 

 

 

 

Copyright notice
This website and its content is copyright of Joe Malone – © Buildingdefectanalysis.co.uk    All rights reserved.
Any redistribution or reproduction of part or all of the contents in any form is prohibited other than the following:
· you may print or download to a local hard disk extracts for your personal and non-commercial use only
· you may copy the content to individual third parties for their personal use, but only if you acknowledge the website as the source of the material
You may not, except with our express written permission, distribute or commercially exploit the content. Nor may you transmit it or store it in any other website or other form of electronic retrieval system.

11 Comments

  • I have a house built in the 1970s. A gable wall is a cavity wall. The brick work above the window has been laid in a soldier fashion and we understand that those bricks were set in concrete and that concrete structure is bridged from the outer wall to the inner wall. Water has ingressed to the inner wall and has passed through the concrete structure. Is the ‘concrete structure’ a building defect or simply a method used in the 70s?

    • Joe Malone

      I don’t fully understand the question based on your description Matthew… Is this a non-traditional property built from poured in-situ or precast concrete? How do you know moisture has progressed to the inner wall because its not unusual for severe cold surface condensation to occur in these solid walled concrete properties?

  • James Stutchbury

    Hi Joe

    Would you happen to know what % of defects are actually “built in” to projects at the design stage?

    I am frequently told that by the time a project/housing development reaches site, the designers have made a certain amount of post-PC issues unavoidable. Would you know if there is any truth in this?

    • Joe Malone

      James, that question is almost impossible to answer. Yes, defects are frequently ‘designed in’ in my opinion but clearly the percentage has to be variable across projects. I am still of the opinion that the majority of defects encountered stems primarily from poor build quality and substitution to poorer quality materials, as part of the ‘value engineering’ process.

  • Hi Joe, Im a damp and timber surveyor/ builder who has 33 years experience dealing with damp issues in buildings. Until recently I was also of the opinion that original physical DPC,s don’t fail. After removing a sub floor with mine fungus, we removed the bitumen DPC from the sleeper wall which had let damp through to the Joists, We removed the black ash mortar joint from below joist level and found this to crumble when touched, this house had rising damp. I have taken samples to get analysed to see why this has happened.

    • Joe Malone

      Hi Dave,

      I’m assuming you’re now saying you believe physical DPC’s do fail? How do you know the DPC had let damp through to the joists? Did you take the subfloor humidity, and if so, what was it? Also, was the bitumen DPC damaged, or are you saying you believe that moisture had transferred through what appeared to be, a fully functional physical DPC?

      Regards

      Joe

      Regards

      Joe

  • Kaz Lester

    Hello Joe, do all parapet walls need an overhang at the top in the form of coping stone/engineering bricks to stop the wall becoming damp please? Mine simply has what the NHBC describe as a ‘cavity closer’. There is no overhang and the brickwork is spalling, mortar is crumbling and the wall is quite saturated. Apparently it’s not covered by the Buildmark Policy as NHBC say it’s not a structural wall. There are 2 issues with this: 1) The house is a relatively new design and I’m not convinced it can’t be classed as a structural wall and 2) I suspect the damage is due to a poor workmanship in the first instance. I was reading about parapet walls on your site and wondered what your thoughts/advice might be please?

    • Joe Malone

      Hi Kaz,

      Firstly, of course the parapet is a structural wall. It forms the outer skin of the building and is tied to the the structural inner leaf. We’re really playing with semantics here, the parapet section itself doesn’t directly support anything but the wall is structural.

      A picture would be useful to see exactly how this parapet has been detailed?

      Yes, the parapet capping or copings should have a minimum of 40mm overhang and a throating detail on the underside of that overhang. They should also be mechanically fixed to the head of the parapet, a requirement we often see missed.

      There should also be a physical DPC under the parapet copings, and this needs a hard support, which bridges the cavity to stop the DPC draping into the cavity.

      How old is the property because it sounds like you have a straightforward breach of contract by the developer.

      Regards

      Joe

  • William Marrow

    Excellent blog. I’m a first time buyer and there’s so much useful information here that has left me much more enlightened. I couldn’t find caulking products part 2 which would be really useful at the moment.

    I did have one query that I’d be interested in your thoughts:

    Our house has blown glass wool insulation done in 2009 and as there was (and is) a working open fire, the installers were obliged to put in new combustion vent.
    There is a 225mm x 125 airvent cover in the living room which is the right size for the room/fire place size but everything else seems wrong…
    The vent has a shutter that can be closed. The fly screen was attached.
    There is no sleeve and no cavity brushes around the vent – not only is the CWI visible above around around the vent hole but the cavity is filled with the rubble from drilling the vent.
    And to cap it off there is a tapered terracotta grill on the outside.

    The installer has gone bust so I had to ask the guarantee agency for advice about carbon monoxide risks and dangers of insulation slumping over the vent.
    The first inspector didn’t understand what the vent was for and the head of inspections saw in person and said its absolutely fine as the installer would have done a smoke test (not documented obviously!) and it’s just building control ‘belt and braces’.

    Given how much emphasis is put in the cavity wall installer’s manual re: ensuring combustion vents are correct and unobstructed this seems like a reckless position.

    I wonder what you would do if you found such a vent on a survey?

    • Joe Malone

      Hi William,

      The rules for venting open flued gas appliances are clear, but do depend on the kilowatt output of the gas appliances installed. The first question must be, do you have any open flued appliances installed? Most boilers these days have a balanced flue and would be described as ‘room sealed’ so do not need a supplementary air supply. However, you also need to consider other appliances, such as gas hobs or log burners, which also may need a supplementary air supply from wall vents. Remember that carbon monoxide is a by-product of incomplete combustion, so it is generated when appliances have an insufficient air supply.

      If you are unsure, then for peace of mind, I’d strongly recommend that you get a carbon monoxide detector installed as a matter of urgency, until you are sure what you are dealing with.

      If there are open flued appliances, then you should have had a flue gas spillage test. If you are unsure then get one done as a matter of urgency. Even extractor fans can cause problems with flue gas spillage, so ensure these are taken into account when the test is done.

      Also work out the total kilowatt output of any open flued gas appliances, and from that you can easily check how many cubic centimetres of ventilation is required.

      Regards. Joe Malone

      • William Marrow

        Thanks Joe, ah good general advice but should have been more specific – it’s a wood and coal open fire.

        The CIGA combustion vent guide 2006 specifies this size of vent for an open fire but as mentioned it says it must be sleeved and the other things mentioned (even if a smoke test is ok).
        I hadn’t thought about extractor fans but yes that’s an important variable as it may not be switched on when doing the test. I have a 24 hour trickle feed DC fan in the bathroom with humidity sensor boosts which is working well at the moment. We have used the open fire with co monitor before we were aware of the vent being unsleeved but I would have thought that CIGA inspector would advise not using it until the vent is changed. I spoke to HETAS today who said it should definitely be sleeved and ideally single unit kit for internal and ext.

        I imagine most companies wouldn’t take chances with carbon monoxide so I’m surprised at the installer and CIGA.

Leave a Reply

Your email address will not be published. Required fields are marked *