Damp Proofing Barn? Injected Vs. Internal Tanking system?

Discussion in 'Builders' Talk' started by SJRuss, Feb 5, 2009.

  1. SJRuss

    SJRuss New Member

    Hi guys,

    I'm in the process of converting a barn - 2ft thick stone walls - rubble infill etc. New concrete floor is in and we've had a quote from a local Damp Proof Company to establish the best course to follow [pardon the pun!].

    They've suggested injected course from inside and out, followed by tanking to 1.5m and overlapping onto new floor. I'm all for the tanking as a good friend of mine used it on 3 similar barns to good effect - but the injected course I'm dubious of.

    Thoughts, suggestions and experiences anyone?!

    Many thanks in advance!

    Si.
     
  2. multijack

    multijack Member

    Do what the pros recommend and get your 30yr guarantee.:)
     
  3. SJRuss

    SJRuss New Member

    That's a fair point I guess - peace of mind and frankly, the worst thing would be damp coming through after it's all been completed. Good spend I guess?

    Anyone else throw anything into this?
     
  4. polly222

    polly222 Member

    SJruss
    if you go for the damp proofing company and you get a 30 year guarantee just make sure its a insured guarantee as half of them arent worth the paper they are written on and i would also check out the damp proofing company.
    I know someone who had damp proofing done and it wasnt done properly and the guarantee wasnt worth anything so be careful.
    cheers mate polly
     
  5. multijack

    multijack Member

    On small refurbs or a short length of problem wall in an otherwise good property there are arguments supporting a less than complete approach but when you consider the financial outlay of a full barn conversion then the amount of money spent on damp proofing it as fully as possible is peanuts really...I dont hesitate on full conversions to get the boys in and let em do what they think is best....and as polly says...check the warranty terms.
     
  6. timbo

    timbo New Member

    Forget any injected dpc's. Use "Newlath" and plaster on top or dot and dab....

    Walls can still breath
     
  7. dangerousdistress

    dangerousdistress New Member

    SJ,

    Injected DPC will never adequately work with rubble fill walls of whatever thickness. There are two many paths for the moisture to penetrate and you will never get a continuous DPC layer. Internal tanking system far more effective. Moreover, as previously said, the walls should be allowed to breath and they will act in your favour to reduce internal damp. Any DPC may trap moisture at low level exacerbating problems and in sever circumstances causing failure of the stone or wall.
     
  8. SJRuss

    SJRuss New Member

    Many thanks for your responses you guys - forums are a god-send, and this one is no slacker!!!

    Okay - so a mixed bag of responses really? Subject to the damp company [whom I've used once before] and the warranty being established, it's a fit and forget/peace of mind effort for both methods being applied. But then if tanking is going to be enough - and it looks like it might be, then I might as well be pumping £500 worth of pound coins into the wall as the injected course won't actually be needed/doing anything?

    Newlath sounds and looks promising as it was suggested also by the company - costs of sheets, fixings etc against tanking though?

    Hmm? Another question would be pointing - is it better to point with sand/cement or lime-mortar?

    Thanks!
     
  9. multijack

    multijack Member

    Sure enough...tanking is a good option...the upside of injection, irrespective of its absolute effectiveness is the 30yr guarantee offered by many companys which can be a good hook for purchasers in the future should you come to sell it...as far as I'm aware there arent similar guarantees available with tanking.
     
  10. alpineskier

    alpineskier New Member

    Personally I don't believe that an injectable DPC is anything other than a con, and subsequently any damp that appears will never be their fault so the guarantee won't come into play.

    But irrespective of my personal opinion, consider it logically.

    The DPC company has no idea of the internal structure of your wall. My barn has walls like this and when I did work on them there were voids all over the place as well as large pockets of dry earth.

    When they inject, how far apart are the holes going to be ? How much fluid will they put into each hole ? What happens if their holes hit a void and all the fluid just drop to the bottom of the wall ?

    Since we know that liquids always follow the path of least resistance, if the fluid is injected into a lump of clay/earth, it clearly is all going to stay in that easy material and not "treat" neighbouring stone thus leaving gaps in the treatment.

    So broadly, I'd say I'm not in favour of DPC :)

    I used lime and sand and found it preferable to cement. It is flexible and won't crack, stays workable hours longer than cement mortar, can easily be knocked off stones if you decide you want to change things and, of course, equally easily off tools if you ever forget a trowel or similar when cleaning-up!

    I also found that the lime I used had a far more attractive colour ( creamy-coloured)that was much nicer with the stones than a matt-grey
     
  11. SJRuss

    SJRuss New Member

    Once again, many thanks for your replies - all things are being taken into consideration!

    @ Alpineskier 1. Did you tank your internal walls then mate? 2. Was thinking along the lines of breathability if I was to tank the walls - waterproofed sand/cement pointing might not allow that to happen?

    Thanks!
     
  12. alpineskier

    alpineskier New Member

    Firstly let me say I am not a professional builder and ask you to take this into consideration.

    No, I did not do any tanking and generally, as far as I know, this is only considered necessary for underground rooms.

    As far as "normal" rooms are concerned even if the external walls are porous, you can separate your internal walls from this with membranes. The question here is, are you - building-wise/intellectually - happy to leave it like that ?

    Don't understand your last remark. As far as I know cement is generally considered waterproof ( yes I know there is a different standard for swimming-pools)

    If you attempt to tank the walls with cement there is NO, NO breathability
     
  13. multijack

    multijack Member

    Firstly let me say I am not a professional builder and ask you to take this into consideration.
    No, I did not do any tanking and generally, as far as I know, this is only considered necessary for underground rooms.
    Don't understand your last remark. As far as I know cement is generally considered waterproof ( yes I know there is a different standard for swimming-pools)


    I am a professional builder and cement is NOT generally considered waterproof.
    As for breathing...the wall has an outside face...it will breathe...if the lower section of the inside of the wall can breathe internally it can also transmit damp.

    I consider injected DPC's to be very good in the correct application and have had several properties both my own and customers and done barn conversions with very good results achieved with just an injected DPC and no tanking/blackjacking.
    As to an earlier suggestion that lime is a nicer colour than grey cement....I presume that you will be skimming internal walls of conversion...still...it might be nice to know that under your plaster there is a nice creamy colour...;-)
     
  14. multijack

    multijack Member

    Oh yeah....and a thread on here has a post from "CornishCrofter" in which he states that he got guarantee work done by DPC company 17yrs into guarantee period. :)
     
  15. Disco Dave

    Disco Dave Member

    Great thread guys! We're just looking into doing a steading conversion so this sort of thing is very interesting. It is interesting to hear that some folks totally rate injection DPC and others think they are a waste of time. I guess at the end of the day the 30 year warranty is what counts as long as you can actually use it if you have bother.

    Dave
     
  16. alpineskier

    alpineskier New Member

    @multijack - re waterproof cement

    I meant cement render being considered waterproof i.e. impervious to humidity.

    Can you tell me how you think the injectable DPC can deal with voids/earth/clay inside wall and spread sideways to form a continuous layer ?

    I think the "retro-fit" DPC is driven almost entirely by the mortgage-lenders who make this a condition of the loan and what the DPC people mainly deliver is a certificate that ticks a box on the contract.

    True there may be no damp afterwards but in many cases there was no damp before: the quality of work in many old buildings is very impressive compared to modern building ( my 1989house -(Beaver/ Twigden ? - was an absolute disgrace of shoddy workmanship and cheap specifying).

    I did have a house with a Rentokil reverse-osmosis electrical damp-course fitted by the previous owner for reasons as above.

    Did it work ? NO. Did Rentokil do anything ? They said the unit was in working order and that was that, even from a big co with a national reputation.

    Finally my inside walls are finished in the same creamy lime, not plaster - or cement :). When I answered the OP , I was, for some reasons, thinking of outside pointin.
     
  17. ecm

    ecm New Member

    I did have a house with a Rentokil reverse-osmosis electrical damp-course fitted by the previous owner for reasons as above.Did it work ? NO. Did Rentokil do anything ? They said the unit was in working order and that was that, even from a big co with a national reputation.

    Electro osmosis DPCs have never been considered a reliable solution to rising damp. They have never held a BBA certificate or BRE approval. In short, the efficacy of these systems has never been proved to any significant extent, which is probably why companies such as Rentokil no longer offer them as a treatment for rising damp. (ok, far too diplomatic - they don't and never have worked)

    The modern accepted method for remedial DPCs is to use an aqueous silane cream such as dryzone. I do agree that rising damp mis-diagnosis and subsequent remedial DPC mis-selling / un-needed application is rife. However, in the correct environment with the correct application products such as dryzone are an efficient way of treating rising damp.
     
  18. multijack

    multijack Member

    alpineskier...
    Cement render is not "impervious" to humidity though it is highly resistant when the correct additives are used...we may both be splitting hairs here. :)

    With regard to injected DPC I believe "ecm" has just done it for me save to say that it is NOT ALWAYS the best solution to a damp problem, only an on site survey can answer this...but heres a link to the older "liquid" injection tech which was largely a forerunner of the "cream" injection.

    http://www.palacechemicals.co.uk/WEBSTUFF/18-6.pdf

    Finally...having re-read the OP I have to admit I missed the referance to pointing and have to agree that lime pointing does have its benefits.

    My most important point in all this has always been that on a barn conversion the cost of the barn plus the cost of conversion is likely to be topping out at over £200k so the cost of damp proofing at £500 is peanuts.

    And I bet your walls look fantastic...:)
     
  19. alpineskier

    alpineskier New Member

    @ ecm + multijack

    thanks for your replies - I looked at the links with interest.

    What struck me though is that both talk about injecting into the mortar and showed exclusively buildings of brick or cut-stone.

    Now this may be entirely reasonable as this is probably 99% of buildings, but the OP wants to know about using this type of DPC on a stone barn with walls 60 cm thick.

    I don't know if his barn is made of mason-cut blocks but I "assumed" this was unlikely and my -admittedly -sceptical replies were based on the walls being of irregular-size natural stone with completely irregular lines of mortar.

    If this is the case and the walls have the voids/dry-earth fill typical of this kind of construction, do you think an injectable fluid/cream can work ? I have to say I still absolutely don't believe it will, although that is based on nothing other than logic and gut-feel.

    @ mutijack

    If the DPC is only required to free up mortgage finance, then of course it is of negligible (financial) importance.

    If however there is a real damp problem that needs solving and this doesn't do it, his real costs risk being much higher through disruption/re-plastering (whatever ) and subsequent attempts to solve the problem.

    I have to say I do like my lime-walls but was unable to get as smooth a finish as I wanted - presumably due to lack of skill/right technique - even when using the finest sand I could source in 35 kg sacks which was 0-2 mm grain size.
    Any advice there ?

    .........................................................

    Would the OP care to tell us if the DPC is for mortgage-purposes only, if there are real damp problems visible and if it is natural, irregular stone walls so we could stop hypothesising ?
     
  20. SJRuss

    SJRuss New Member

    Hey guys,

    I haven't gone anywhere - just reading the replies with interest.

    To clarify - the barn we have is 2 foot thick stone with a centre cavity [if you like] of 4 inches of dirt/random rubble infill.

    From discussions with our builder, it appears that even the local BR have suggested, off the record, that these are ineffective, and that tanking is the better method?

    With our barn, we just want to apply the best method, without wasting money, to ensure that we don't get a problem when the finishes are applied a few months down the line. We don't actually have a damp problem as yet?!
     

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