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.

    • CommentAuthorwellburn
    • CommentTimeJan 19th 2019
    There are many threads about insulating a suspended floor, and with only a small ccawl space, means lifting nearly all the good T&G boards to install.
    That is a big job, disruptive to skirtings etc, and with potential 25% board loss, means the floor will never be the same again.

    I know that the phenolic spray insulation for attics / roofs is flawed, and often damaging, but does the logics apply to underfloor voids too?

    Q-bot seems to be some university robot & AI project that is starting to be commercialised, so its new ....

    Its a robot that goes into the sub floor void, and sprays Phenolic / PIR insulation ALL OVER the joists and floor boards from underneath.
    It seals all the gaps, makes them air tight, while still retaining the all important air flow underneith.

    I am fully awair that sprey chemical foam insulation has been mis sold as a (bad) solution for roof insulation, and has caused many serious and exensive issues.
    BUT - the very reasons why spray foam insulation is bad for a roof, may actually be very appropriate for a floor.
    Roofs are VERY expensive. They are inaccessable, and need to deal with a shit lot of extremes from both inside and out.
    Work on them is expensive because they are ...... inacsessible to nearly everyone.
    They are also 'out of sight, so out of mind'
    Damage can be slowely happeneing for ages without notice, and then .... its a REALLY big deal.

    Floors on the other hand, are mostly exposed to a fairly steady and constant regeme, and and issues are noticable pretty quite (by me at least)
    AND - if bad things do happen, anyone can get at them, and .... while a nusance, it is not 'catastrophic' - its just work, that even a DIY'er can do.

    OK, the spray robot is not cheap ... but it is quick, and .... deals with the detailing, coz it just sprays its chemical foamy stuff all over everything, so not gaps, or cold bridges or whatever.

    BUT - lifting the floorboards, has got to be a labour of love, its a lot of hours, and many opportunities to get the micro detailing wrong .... and end up with a soggy joist a few years later.

    No sales people, - I just came across them, its a spin off from some university research project, that hasen't been commercialissed yet ... as I understand it ....

    They don't claim anything, they have a website, and .... whatever.

    Anyhow, when asked, they suggest:

    "We normally apply 125mm of insulation, resulting in a post U-Value of <=0.25 W/m2/K (depending on void conditions). The results across 100 homes show an average post-installation of 0.19 W/m2/K, representing a 79% improvement compared to before."

    I know that paying for underfloor insulation is unlikely to ever 'pay off' - but I do want to try my best, and the floor boards and especially skirting boards are really deep and beautiful, and I really don't want to trash them.

    Here is a video link:
    Q-Bot, robotic device lowers insulation costs | 2018 Ashden Award

    Any thoughts?

    • CommentTimeJan 19th 2019
    Might be worth following up. Ask for references; go and see a job or two; what's the warranty and how insured; what's the cost after discount for early adopters etc.
    • CommentAuthortony
    • CommentTimeJan 19th 2019
    It doesn’t work, real subfloor have too may probs, junk, wires and pipes, uneven, sleeper walls etc
    • CommentAuthorgyrogear
    • CommentTimeJan 20th 2019
    rather than insulate the sub-floor, try insulating the peripheray walls instead - less gear, less hassle !

    • CommentAuthortony
    • CommentTimeJan 20th 2019
    From inside or from outside and what about the cavity?
    • CommentAuthorandyman99
    • CommentTimeJan 20th 2019 edited
    Take a look under your floor in a couple of places and see what state it's in. I have spent the last 6 months lifting all my floors and replacing. I agree with Tony, what a mess, rubble/bricks/wood/current pipes/wires old pipes/wires etc. Your house may be in a better state of course!
    Also there are the dwarf walls to consider, so it would only be able to work in sections.

    I did investigate this some years back for a beam/block concrete floor, but then there wasn't enough depth. I seem to remember that they wanted a good smooth surface for their robot. May be more tolerant now of course.
    Has a full fill with EPS beads gone out of favour - or is the crawl space too deep (= too much volume (expense))
    • CommentTimeJan 20th 2019
    I know some of the Q-bot people. They wouldn't be pushing it if it was snake oil, I think.


    • CommentAuthorgyrogear
    • CommentTimeJan 20th 2019
    Posted By: tonyFrom inside or from outside and what about the cavity?

    from inside:
    per another place (...):

    seal up all existing ventilation grilles save one, and force a small quantity of house-air into the void (1 cfm per 50 square foot of area), thus creating a conditioned crawlspace.

    Requires a very small extraction fan on the remaining vent...

    The makeup air entering the crawl space is conditioned air from the house upstairs; since this conditioned air is drier than outdoor air, it doesn't lead to condensation problems.

    (also expels any radon that might be around...).


    • CommentTimeJan 20th 2019
    Posted By: gyrogearThe makeup air entering the crawl space is conditioned air from the house upstairs; since this conditioned air is drier than outdoor air

    Err, not usually. Interior air is usually more humid than exterior air in a heating climate.

    If you're thinking of RH, then of course that will increase depending on the temperature decrease in the crawlspace.
    • CommentAuthorgyrogear
    • CommentTimeJan 20th 2019

    Err, not usually. Interior air is usually more humid than exterior air in a heating climate.

    djh, do you really believe that ? !


    • CommentTimeJan 20th 2019
    Yes, the article is confused and relevant to a different climate. The dryness it is talking about is low levels of RH.

    Think about it - in this country the problem is usually condensation and mould. Interior air has the same absolute humidity as the outside air PLUS whatever is generated by breathing, washing, cooking etc.

    Dry air in winter is only a problem in over-ventilated offices and passivhausern in this country.
    • CommentAuthorwellburn
    • CommentTimeJan 21st 2019
    thanks for the comments, I cannot 'insulate' my walls / foundations as mid terrace.

    Removing / ripping up TnG flooring is a major task, and managing the detailing on dwarf walls, and where joists rest on / in walls is near impossible detailing to get right even then.
    BUT - what is the purpose of venting the sub floor? - Is it to ensure that the joists get ventilated? - if so, then surely ANY insulation negates this ability for the exposed timbers to be ventilated.

    YES, the void is full of junk. bricks, pipes n wires etc.
    I could crawl round to collect / move, but definitely not enuf space to apply insulation from under, unless you are a robot .....

    My local housing association have signed up for it.... but that doesn't mean it is a good ideas.

    What might hypothetical problems, be?

    The easy alternative is to not insulate the floors..... which also has a cost ....
    • CommentAuthorTimSmall
    • CommentTimeJan 23rd 2019
    Posted By: wellburnBUT - what is the purpose of venting the sub floor? - Is it to ensure that the joists get ventilated? - if so, then surely ANY insulation negates this ability for the exposed timbers to be ventilated.

    There are many previous threads on here about this, but if the insulation is installed so that you're warming all the timber up (moving it inside the thermal envelope), and it also isn't getting damp through direct contact with damp masonary etc. (e.g. there are DPCs, or other types of "capilary breaks"), then no problem if the underside of the timbers aren't ventilated in general.

    Strictly speaking you could still get problems with a vapour impermeable floor covering e.g. PVC flooring, but this also goes for un-insulated timber ground floors...
    • CommentAuthorTimSmall
    • CommentTimeJan 23rd 2019
    e.g. see this article:


    (... its east coast US centric, but largely applies to UK too, although some of the problems are a bit less extreme in the UK - depending on location within the UK).
Add your comments

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

© Green Building Press