Have to flash between conc and c/steel . there are a few options on the market, but stupidly expensive for a sticky tar on a substrate of some sort ! An old Dutch solid plasterer told me they used Hessian cloth and tar then aluminium paint for sealing a flat roof . I have yet to check out that butenol stuff . any cleaver and cheap solutions ?
trade4us2,
May 29, 5:50pm
Butynol is good. Glue it on with contact adhesive.
I couldn't agree more; any weatherproofing that relies on glues or sealants should only be looked at as a temporary fix . I'd recommend Metalcraft Roofing (there's a branch in Tauranga) for sourcing suitable flashing. They're more that happy to cut and bend Coloursteel flashing to your design at a very reasonable price.
This is a great source of info, (have a read of page 164).
The roofing code of practice mentions sealant 143 times, here's one of them
"In very high wind design load areas and where the pitch is below 10Ëš, mating flashings must be sealed and fastened with sealant at each end of the lap to prevent the ingress of dirt or water."
UV damage kills most afterthought attempts to seal.
the-lada-dude,
May 30, 7:34am
Thanks fella's . one quote for the steel flashing was V costly . more research needed
happychappy50,
May 30, 7:38am
Obviously that is referring to a lapped joint where a sealant is used as a 2 nd line of defence
trade4us2,
May 30, 8:23am
We have used Butynol for many years. I am not aware of any problems with it. Please explain any potential problems if any. It's been on our seaside bach roof for over 50 years, and on my current house next to corrugated steel for 25 years, and I have just used Butynol for a large diaphragm, having tested it by stretching it by 50% 10,000 times. I also use Butynol to replace all kinds of rubber seals.
pauldw,
May 30, 10:10am
Probably a zincalume thing.
pauldw,
May 30, 10:20am
2nd line or not it's still essential in many cases. It's done at the time not squirted on outside afterwards where it will sit in the sun.
martin11,
May 30, 2:21pm
Years ago I owned a hanger at Christchurch Airport in a block with some others .the ones that had inbuilt gutters done in Butynol failed and started leaking within a few years . The only cause found was the Jet a1 from jet fuel from the planes on take off affecting the Butynol . In certain winds you would have a very strong smell at the hangers when planes were taking off and landing . The Butynol went very soft and perished .
tweake,
May 30, 4:31pm
the surface goes 'dusty'. really noticable when you walk on it. not really a problem but i have seen it go flaky on top. joins coming apart. worse one was couple of meters long lap seal that folded back over.
there some sort of commercial version which is meant to be really good. ran into it once on a new house i was working on.
stevo2,
May 30, 5:39pm
We never use Butynol. So many issues with it these days. We always insist on a product called TPO. Really solid and joins are thermally welded together.
golfdiver,
May 31, 6:39am
Black butynol has carbon in it. This reacts with colorsteel and eats it. You must have a separation barrier between them. We have recently reroofed a property under warranty for NZ steel. The muppet who put it on laid the steel directly onto the butynol that was finished up and over the bottom purlin. It absolutely destroyed it. The grey stuff seems ok at this stage.
tegretol,
May 31, 12:29pm
My 60's stucco and longrun house has absolutely NO sealant anywhere on the exterior. No leaks ever. Doesn't that say something about the sub-standard designs that are being built today?
golfdiver,
May 31, 5:33pm
No what it says is that it was built with Galv which while inferior to Zincalume for corrosion resistance was able to be soldered. In the next decade, you will more than likely need to replace that roof and let’s see how you get on without sealants then.
tegretol,
May 31, 7:57pm
I am gradually replacing it with .55 ZA and the only area I can see an issue with will be the chimney flashings. Leaving the ridge caps intact as they are as solid as they were when fitted.
pauldw,
May 31, 8:40pm
Do they have lead soft edges?
martin11,
Jun 1, 7:58am
Sealants are only a temporary solution and a lazy persons product . They mostly all fail after about 15 years and some that are exposed to sunlight even earlier because of the uv . There is no real substitute for properly done flashings . You only have to wander around a house about 10 to 15 years only and look at the colour steel gutters most joints will be leaking .
tegretol,
Jun 1, 9:12am
Yep and all in immaculate condition, even after being slightly/carefully lifed for the new iron.
golfdiver,
Jun 1, 11:16am
And they are going to react with and rust out your new roof. You can’t use lead with zincalume
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