expanding foam with ultra-fine nozzle?

I'd like to inject some expanding foam between the corrugated asbestos sheets forming my garage roof, to prevent rainwater ingress, when the wind is blowing in the same direction as the slope of the roof. The standard expanding foam canisters have an applicator that is betqwwn 5mm and 10 mm OD. I need something that is more like 2mm! Can anyone suggest how I might achieve this? Un fortunately, it would be very difficult to pry the sheets apart whee the overlap, as they are securely nailed ti the roof joists with 6" roofing nails.
Many thanks...
JD
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JakeD wrote:

Is it possible to use a silicone mastic with a fine nozzle end?
Cash
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I wondered about that. I can give it a try.
However, now I have inspected the underside of the asbestos idn broad daylight, it looks as though the moisture is actually bleeding through the affected sheets. Most of the sheets are impervious and dry on the underside. Just a couple of them seems to be allowing water to bleed through.
Any suggestions what I could paint onto the top sides of the sheets to waterproof them? Something clear, that won't colour the sheets would be ideal, because I don;t want the painted sheets to sook different from the reat, and the roof is too big to paint the whole lot. Would diluted PVA do it? Or is there something better?
Thanks to all respondees.
JD
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Not sure PVA will put up with repeated wet dry cycles will it?
How about something like http://www.toolstation.com/shop/p56806 ?
Or cheaper (not as good, but maybe good enough?)
http://www.toolstation.com/shop/p17776
Darren
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snipped-for-privacy@auk.kent.ac.uk (D.M.Chapman) wrote in

Thank you for these suggestions. The last link above looks like good value. I'm always a bit wary of buying products where they don't specify the ingredients (in case I'm just buying diluted PVA, but at double the price).
Can anyone else comment of the suitability of PVA solution and/or Everbuild Waterseal and/or Thompson's Waterseal?
JD
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JakeD wrote:

JakeD,
Providing there are no cracks in the sheets, you could spray or brush on a clear silicone waterproof coating over the whole roof which may help.
My advice though (funds permitting) would be to re-roof with Colour Steel sheets (can be laid on top of the old sheets[1]) to give long-lasting weatherproofing[2] as asbestos sheets are a beggar to seal once they become porus[3].
Have you checked the sealing washers under the fixing to see if they are doing their job as this could possibly be the cause of the leak - especially in heavy rain?
[1] This method will also negate having to dispose of the old sheets.
[2] A neighbour of mine did this some five years or so ago to great effect.
[3] You could also lay UV resistant plastic or pond liner over the asbestos as a temporary sealing measure and fix the overhanging sheet with battens screwed into the walls just under the roof eaves.
Cash
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Yes, the washers seem okay. I think it's just a couple of the 30-odd sheets that are letting rainwater bleed through, so I'd like to try the most affordable-but-effective clear liquid sealant first, before going for anything more expensive. Thompsons Waterseal or Everbuld Waterseal (are they the same thing?) look interesting. Has anyone used these products and found them effective and long-lasting for exterior use?
Many thanks,
JD
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On Friday, December 27, 2013 11:28:52 AM UTC, JakeD wrote:

ts

d

I think for £12 you may as well just have a go & see if it sorts the prob lem?
Jim K
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That may be the thing to do, but I thought I'd ckeck first - in case, say, anyone has found the stuff to have undesirable effects on asbestos or whatever. In the field of DIY and building materials, I've learned to try and avoid taking anything for granted.
JD
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the > problem?
That may be the thing to do, but I thought I'd ckeck first - in case, say, anyone has found the stuff to have undesirable effects on asbestos or whate ver. In the field of DIY and building materials, I've learned to try and av oid taking anything for granted.
JD
End quote/
Judicious googling will alert you to any obvious pitfalls with a plan. Rely ing too much on stuff on here without further checks is inept if not stupid sometimes.... Jim K
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I agree.
JD
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PS...
However, I'd much rather pay heed to people's first-hand experience of a product than the hype used by the advertiser/distributor/manufacturer to sell the product! (Nosiree, things haven't changed much since the days of 'snake oil'!)
JD
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On Friday, December 27, 2013 10:39:35 PM UTC, JakeD wrote:

mmm by now I would have thought if someone had had your particular issue they would have contributed on one of your threads (if they were going to). Seems the answer is "we don't know but here are some theories" & for 12 quid - blaze your own trail!
Cross your fingers & let us know if it works or not.
If that's too much of a gamble I don't think you should be DIYing it. Get your cheque book out for a couple of hundred, pay a man (if one will touch it) and then er.. cross those same fingers ;>)
Jim K
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So, on the one hand you're saying "Relying too much on stuff on here without further checks is inept if not stupid", and on the other you're saying "Cross your fingers & let us know if it works or not."

I don't have a problem with that. If you do, why waste your time in this thread?
JD
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On Saturday, December 28, 2013 10:24:05 AM UTC, JakeD wrote:

yes.

because I think you maybe a troll.
You start multiple threads with the same issue, last December being a good example, remember this?
"12/19/12 Hi all,
I have a double garage with a sloping 'big 6' corrugated asbestos roof which is about 30+ years old. The roof joists are getting very wet in places. At first I thought it must be due to rainwater getting in through one or two of the holes through with the 6" galvanised roofing nails were driven. However, after carefully sealing any possible such leaks, the wetness continues. Yesterday (which was a cold but rain-free day), I went into the garage and inspected the roof, just after nightfall, and I discovered that almost the whole underside of the roof had a lot of condensation on it. Since the roof is gently sloping, that condensation runs along the enderide of each corrugation ridge, until it meets a joist. That is where the water gets into the wood. One weird thing I noticed is that some sheets of the asbestos seem more prone to condensation than others.
Are there any tricks I can employ to stop the condensation?
If not, does anyone know of any way to divert the water away from the joists? I thought of gluing a short length of string to the underside of each ridge, just upward of each joist, so that the water drips down the string and into the garage... but it's not a very satisfactory solution, because I have a lot of perishable stuff stored in the garage.
Can anyone offer any suggestions?
Thank you...
JakeD"
Jim K
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Get a life! (...and welcome to my killfile.)
JD
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On Saturday, 28 December 2013 13:33:29 UTC, JakeD wrote:

Suspect its not me that needs a life...
With an apparent grand total of 53 odd messages on usenet I am surprised yo u feel the need to have one....
or do you have other aliases like colonel scott, kruger etc?
ICM5£ ;>)
Jim K
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On 28/12/2013 16:54, Jim K wrote:

Jim
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On Sunday, December 29, 2013 2:41:21 PM UTC, Bill wrote:

grow up "Jake" & see you next christmas with the garage thread (again)
Jim K
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On 25 Dec 2013 22:51:01 GMT, JakeD wrote:

So along the sheets not up the corrugations where they rest on the wall plate? I'm surprised water is getting in there, have the sheets got the correct overlap? Two full crests IIRC.
Foam isn't really the right stuff, from a can it's open not closed cell so water will get through it. As some one else said a good bead of exterior grade silicone along the edge of the sheet is probably you best bet, having cleaned/removed any loose material first.
If the sheets are just nailed on is there any sealing washer under the nail heads?
--
Cheers
Dave.
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