Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)


Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!

powered by Surfing Waves

Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.

    • CommentAuthorDWHITE
    • CommentTimeApr 1st 2022
    Hello everyone. First time poster, long time lurker etc. Will try to keep this brief but am looking for some guidance from the experts.
    This is my first attempt at some home renovations on my first home so please be gentle. Limited DIY skills being a simple data analyst but learning as I go. I've started in our spare bedroom on the first floor which is my covid office. Cold draughts from under the skirting, particularly from the wall which looks out over the front of the property. I've been using posts within the forum and the excellent readinguk.org posts as guidance but wondered if I could get your opinions on how best to deal with a couple of specific issues I've hit.

    Context: 1990 end of terrace 3 bed house. Block and Beam ground floor. Dot and dab plasterboard. Aircrete inner leaf. Integral garage... Can't think of much else but assuming I've captured most of the bad-house-bingo marks there.
    So far I’ve had the cavity fully filled (60mm) with polypearl platinum eps beads and have been working on filling the loft with 500mm of insulation although I will be going back up there to address some of the penetrations.
    I am attempting to do the actions listed in the following:

    Question 1: How best to fill an 8cm diameter hole within the aircrete block? I can see the outer leaf brickwork through it.

    Question 2: How best to deal with a 20cm diameter hole which has both cables and pipework going through the wall and entering the roof space above our front door entrance and downstairs loo. The aircrete block is crumbling here and around half of the hole is covered in EPS beads from having the cavity filled.

    Question 3: Between the inner leaf block and the ceiling/wall plasterboard joint of the room below there is a gap is a 2cm gap followed by a 28cm drop to the next aircrete block where I can see a metal lintel. Would you run gap foam around in a similar manner to the readinguk.org first floor voids article or would you attempt to put something down there such as insulation around the metal lintel?

    I am trying to publish photographs of the above areas however it is my first time posting photographs on the forum.
      First floor voids.jpg
    • CommentAuthorDWHITE
    • CommentTimeApr 1st 2022
    Hole 1 - 8cm dia
      Hole 1 (1).jpg
    • CommentAuthorDWHITE
    • CommentTimeApr 1st 2022
    Hole 2 - 20cm dia - cables and pipes running through to roof space above front door and downstairs loo
      Hole 2 (1).jpg
    • CommentAuthorDWHITE
    • CommentTimeApr 1st 2022
    2cm gap with a 28cm drop down to a void along the metal lintel.
      Gap down to metal lintel (1).jpg
    • CommentAuthortony
    • CommentTimeApr 1st 2022
    Been there already , not just you but millions like it and they are still building them


    I am not certain, but I suspect that graphite EPS (which you have as CWI) does the same to cable sheathing as white EPS, so try to end all contact between the two.

    Your Q1: Hmmm.... You can see the outer leaf? So where's the CWI at that point? The answer to that sub-Q may affect whether or not you go straight to:

    Get yourself a small piece of 3-4mm ply, narrow enough to go through the hole (less than half the width) but taller than the vertical height of the hole. Drill a hole in the middle of the ply and thread some wire in, with plenty of spare lgth. Thread that wire through a similar piece of ply so that the 'gizmo' looks like an ice-cream wafer sandwich without the ice cream. Push it over to one side of the hole. This then holds the (sticky as possible) mortar in place while it goes off. A bit of PVA on the block will help adhesion (and I think they 'suck' like mad, too). Rinse and repeat, leaving a small final gap through which you are going to try to insert some CWI, before closing up.

    Q2: Urgghhhh. (a) worry (at least a bit) about the cable/bead contact, then separate them, then possibly stop worrying (I am not an electrician!). Do a variant on the above. Use some sort of winding to bunch cables together so that you have more space to fill. Get an elec's advice. Q: How to seal draughts while leaving yourself the ability to do future work to plumbing or elecs?

    Q3: Cannot really see, but same as above re cables. I hate squirty foam but... maybe squirty foam? Usual H & S advice.
    • CommentAuthorDWHITE
    • CommentTimeApr 1st 2022
    Thanks Tony, I am actually working my way through the steps within that link but it's more that I'm unsure of how best to approach the above issues I've run in to and was seeking some guidance.

    Was possibly thinking:
    8cm dia hole (1) - Expanding foam then carry on with the insulating board foamed over in line with the boarding between other joists.

    20cm dia hole (2) - Attempt to bunch cables and pipework together through as they enter the wall. Use insulation board with a cutout for the penetrations to pass through, foam this to the wall and use airtight tape around the cables/pipes on to the insulation board... Will this work well? Should I use expanding foam in the hole given there's services going through?

    Metal lintel - Poke wool insulation down along the lintel as best I can and then carry on with gap foam along the plasterboard?
    • CommentAuthorDWHITE
    • CommentTimeApr 1st 2022
    Thanks Nick,

    Really interesting re the ply! Will be re-reading that at the weekend, with a coffee while the partner and baby are out to accurately picture what is going on but sounds logical!

    I assume the CWI has spilled out as it has done in several other places. I'm actually due to pick up some EPS beads from a local supplier next week. Looking to attempt filling the gap between the plasterboard and inner leaf following this: https://readinguk.org/draughtbusters/basic-techniques/walls-and-windows/.
    Ultimately hoping to fill the void between my block and beam and close off the vents but that'll perhaps be this summer some time.
    • CommentAuthorphiledge
    • CommentTimeApr 1st 2022
    Firstly, good on you for making a proper effort to improve things and all the more so as youre not a tradesman

    Where you can see the outer leaf of brickwork from the inside there should be insulation beads. If the CWI came with a guarantee I would make a claim on the guarantee. That may initially seem over the top but when we made a claim a surveyor came out, drilled lots of small holes in the outer leaf of the wall then used an endoscope to check for full fill of insulation. He found many more areas of missing insulation than we had spotted looking down into the cavity with the edge of the roof stripped off. He put together a schedule of remedial works which was completed a few weeks later. Talking to the surveyor he knew from experience the areas that would have be missed and also by looking at the original injection hole positioning. Claiming on the guarantee was a very easy and productive process.
    Ah! Read too quickly. Missed the dot and dab. You know what you must do!
    • CommentAuthortony
    • CommentTimeApr 1st 2022
    I quite like pushing fibreglass blob into big holes then foaming over the top of them and sticking board over the whole lot.

    I don’t like tapes, they seem too temporary.

    I don’t worry about cables in contact with eps, foam seems OK though.

    Well done tackling it. Happy to look at more pics and advise
    • CommentAuthorDWHITE
    • CommentTimeApr 2nd 2022
    Philedge, really interesting! I would never have thought of making a claim as I assumed the beads had just fallen out of any holes and that would be beyond the reasonable ask of a CWI installation company to compensate for. I will have a look around in there with a torch and then give the claim a go I think.


    the fibreglass blob followed by foam and board option sounds reasonable. It feels as though, should there be any issues then this approach is more easily reversed than masses of expanding foam everywhere!

    Hoping to tackle it over the coming week on lunch breaks and some evenings. Really appreciate the support and praise all. Definitely helps with the motivation. Such a great forum!
    • CommentAuthorphiledge
    • CommentTimeApr 2nd 2022
    Posted By: DWHITEPhiledge, really interesting! I would never have thought of making a claim as I assumed the beads had just fallen out of any holes and that would be beyond the reasonable ask of a CWI installation company to compensate for.

    If the 80mm hole is as you found it and youvev not removed any beads, then thats a defect. You can probably deal with that hole on its own but how do you know there arent more areas with missing beads?

    With ours I estimate that we had 10-20% of our insulation missing. Very few places had the insulation to the top of the cavity and 2 corners had the insulation 2-3' below the top. We had internal condensation issues in both those corners and its no wonder with just a single brick between the room and the chilly winter air.

    Make a claim and the surveyor should know exactly which areas will have been missed.
    • CommentAuthorgravelld
    • CommentTimeApr 3rd 2022
    I quite like Blowerproof for odd sealing jobs. It lasts for ages so long as you re-seal the bucket. I'd go over any edges of ply and all of any foam or whatever you've stuck in with 2-3 coats.
Add your comments

    Username Password
  • Format comments as
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   

© Green Building Press