Leak that is driving me crazy

I purchased a 1964 designed house about six years ago. The architect when designing the roof in his wisdom put fall from both ends of the house into the centre of the dwelling. The runoff flows into a box gutter (6m x 200x 150) that runs smack bang through the centre of the house. The problem is that the bloody thing is always leaking as it deteriorates. Over the years I have had several occasions where water damage occurred

There are two issues. I will be putting another story on in three years so I don’t want to go to the expense of a new roof. Also due to certain issues it is extremely difficult to replace the box gutter. I have tried two different sealing compounds but after short time they crack and cause leaking.

<O:p</O:p
My question is there any suggestions on what I can do to seal this gutter before they have to put me away.

I know how annoying leaks can be and that design is one I've seen a few times but is just asking fro trouble.

It's just a suggestion but would fibreglass work maybe ? The trouble could be getting it to stick which means removing all dirt etc.

You might get away with painting it with a waterproof membrane. It would need to be one that's okay outside (as opposed to one that's designed to go under tiles)

Mick

PS Bloody architects!:(( (well silly ones that use box gutters where they don't really need to)

'64... I imagine it's gal and not aluminium? Maybe good, old fashioned lead solder? Not recommended if it's running to a tank, though...

Oddball geometry suggests the gutter has insufficient slope. Street gutters are usually 1/2% minimum but still get birdbaths due to construction tolerances; 1% better, 2% better yet (minimum cross-slope on roads and bridges).

For only a few years protection, might be easiest to build up a mortar trough with proper slope, and slather with sealant as if it was free, at least at the boundary with existing roof surface.

Joe

That's called a butterfly roof. People are still building them despite all the problems they have with leaking gutters.

Maybe you could have a new box gutter folded up that is small enough to slip in over the old one without removing it?

You could try getting a roll of malleable aluminium flashing that is wide enough to shape to the inside of the gutter and long enough to run the full length.

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Originally Posted by mat

You could try getting a roll of malleable aluminium flashing that is wide enough to shape to the inside of the gutter and long enough to run the full length.

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That's a good idea.

The cheapest solution if the holes are small and identifiable might be Selleys Marine sealer. I used this on my tinny when I drilled holes for the sounder below water level and it withstands salt water very well so should handle rain water. It's also flexible (rubbery) when dry so wouldn't crack.

HH.

Trust me, no sealant will last in this application for three years. You can make up new trays or overflashings if you want to go to the trouble, but a waterproof membrane will be the easiest option and probably the cheapest.

Mick

Mick knows best! :2tsup:

If you could knock the ends out so there was no chance of overflow, that'd help too!

Cheers,

P

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Originally Posted by journeyman Mick

Trust me, no sealant will last in this application for three years. You can make up new trays or overflashings if you want to go to the trouble, but a waterproof membrane will be the easiest option and probably the cheapest.

Mick

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Hey Mick,
Do you think that product called "Pondtite" would work, it is the stuff for painting the inside of cement/concrete fish ponds. It's safe for fish so should be good for rain tanks, it seals porous materials so the water does not leak out nor the lime and other things leech into the pond water and it's meant for outside use, what do you think.

Thanks for all your great suggestions. Yes it is a gal guttering and yes the fall is incorrect and pools of water stay in the gutter. Tank water is only used on the garden. My concern is if I make it any smaller the volume of water cannot get away. Twice we had a rainstorm where the water could not get away quick enough and like most box gutters it flowed up and under the roof sheeting into the house flooding three rooms.
<O:p</O:p

I tried bit coat but that was no good. I then tried a product called Emer-clad but it seems to crack in places after a couple of months.
<O:p</O:p

I wonder if fibre glass would work. Also the malleable aluminium sounds like a good idea. Is that sold through plumbing supplies?

The pondtite might work, but being for underwater use may not be UV resistant. The stuff I'm thinking of is used to flash parapets and roofs and there's even trafficable grades for flat rooftops. Sorry but I don't know any names. If possible I'd enlarge the downpipes and outlets and fit overflows or knock the ends out like Midge suggests.

Mick

Aluminium flashing is available at plumbing suppliers, roofing suppliers, builders suppliers and even Bunnings (small selection)

It sounds like you have two problems though. Not enough capacity to remove water quickly ? blockages further down ie down pipes or even pipes in the ground. Are the pipes earthenware in the ground? Unlike traditional gutters that overflow to the ground when the pipes don't cope your overflow will always go straight in the house. This sounds like you biggest problem. Agree with midge - look to create an overflow out the end or ends.

The second problem is the waterproofness of the gutter.

Aluminium flashing into gal gutter and your gutter will be rusted out in short time by electrolysis so no go.

Two issues to fix:

1. Leaking gutter - So long as the gutter is cleaned according to instructions silicone sealants for gal should last 20-30 years. But this is probably best repaired using a full two-part waterproofing membrane system - talk to Bunnings. There are a number of product that will do the job.

2. Overflow - this can be fixed by effectively extending the gutter higher up the rafters on each side using ponding boards or sheets. These are lengths of galvanised flat iron bent to have a lip that sits down into the box gutter 30-50 mm and sit on the rafters under the tiles or sheeting - on top of battens usually.

They are pop riveted to the existing gutter, but if access is an issue can even just sit in place with silicon sealant liberally applied underneath to seal between the gutter and the back of the ponding sheet. If tiled roof then lift tiles and take the sheet say 300 mm up the rafters - a big increase in the holding capacity of the box gutter. If colourbond or similar roofing then simply undo the screws sufficiently to slide the ponding sheet up and under.

The other issue is the size of the outlet - it won't matter how big the box gutter is or is extended by ponding boards to be if the outlet is a 90 mm or 100 mm downpipe into a 100 mm storm water drain. So many houses have overflowing gutters because they have several downpipes (and/or a box gutter) all of which flow into a single 100 mm stormwater connection.

As others have said you need to enlarge the outlet at the end of the box gutter to the max and also have at least one overflow grate/ sump at ground level so that in downpours there is somewhere to ease the restriction of flow. And as was also said - check there are no blockages in the stormwater system.

One other thing - one fundamental bit or work that almost no-one does is to work out what carrying capacity the gutter and stormwater system as a whole needs to have.

To do this is simple enough - work out the surface area of the roof sections that will have rain flow into the gutter then visit the BOMS website http://www.bom.gov.au/hydro/has/FAQ.shtml and other parts of that site and look up the local rainfall history to find out the 15-year, 25-year 50-year and 100-year maximum rainfall events, work out the volume landing on each square metre and multiply by the surface area of your roof so you can then determine the maximum volume of water that has to get away down your gutters and drains. 1 mm of rain on 1 square metre of roof is 1 litre - so for example if a single 15-year event drops 30mm in an hour and you have 50 square metres of roof flowing into the box gutter then the system needs to handle 1500 litres in that hour - ie: the smallest outlet has to manage a good proportion that volume or your gutter will fill up and then overflow.

Residential guttering are usually built for 15-year events, occasionally for 25. This means that if you happen to have a more severe event then you have to make sure that the overflow goes to the outside of the house and stormwater system so it does not cause any damage. These estimates of the occurrence of these events are based on historical data which often goes back just 60 years or less and the risk of the events are based on good science, but are on averages over a long time. So it is quite possible to have two 15-year events within a year (or even within a couple of weeks).

As above, once you have done what is reasonably possible (given access, time, technology and money) to secure the gutter as to size and being fully waterproof, the key is to make sure that any overflow goes where it will do the least damage ie: onto the ground.

Sorry if that is all a bit repetitive.

Bloss

Are you sure aluminium causes gal gutters to rust. I have aluminium flashing going into gal gutters for years and have had no problems.

Aluminium swages are also used on gal wire so I can't see how there could possibly be a problem.

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Originally Posted by mat

Bloss

Are you sure aluminium causes gal gutters to rust. I have aluminium flashing going into gal gutters for years and have had no problems.

Aluminium swages are also used on gal wire so I can't see how there could possibly be a problem.

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Mat,
you sure your gutters aren't zincalume? Zincalume is compatible with aluminium, while I'm pretty sure gal isn't. I also suspect that modern fencing wire isn't "galvanised" but more likely zinc or zincalume coated.

Mick

Another product you could try is sikaflex.
I fabricate aluminium windows and this is used around windows to seal between the frame and brickwork.
it is flexible so it wont crack and if needed can be painted over.
It is also a variation of the same stuff used to hold in car windscreens.
it is by bostitch and sold in 10-12 inch sasuage.

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Originally Posted by commoo

Another product you could try is sikaflex..................
it is by bostitch and sold in 10-12 inch sasuage.

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Actually "Sikaflex" is made by Sika Industries. Bostik make Seal and Flex, Ultra and Matrix amongst others. Bostitch makes nail and staple guns. I've used all of them (plus own a few Bostitch tools:wink: ) and still reckon that no sealant will last 3 years in this application.

Mick

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I'm pretty sure gal isn't

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I don't really understand the chemistry behind it all but galvanising is done by hot-dipping steel in molten zinc. The zinc prevents the steel from oxidising but it does not prevent electrolysis occurring between different metals, such as aluminium, in the presence of water.

As far as I know, the only difference between Zincalume and normal gal is that the coating also contains aluminium. Why that aluminium doesn't react with the steel underneath in the same way, I don't know, but I imagine it is to do with the way it has been bonded to it during the galvanising process.

So, pure zinc-coatings used in galvanising can still allow electrolysis to occur between the steel and aluminium (or other metals). Zincalume to zinc-coated (galvanised) steel can also cause problems (eg. Zincalume roof into a galvanised iron tank). Galvanised steel lintels in contact with aluminium window frames are also bad.

However, Zincalume and aluminium are OK together. I'm sure Bazza would be able to explain why. All galvanised wire is coated with zinc, but it may also have aluminium in the mix, which is why fencing wire and aluminium swages would be OK. I guess.

Unless you know the gutter and downpipes are Zincalume, or unless they are Colorbond, I'd stay away from aluminium.

See the link I posted here:

http://www.woodworkforums.ubeaut.com...ad.php?t=48057

Zinc is sacrificial to both steel and aluminium.

Most downpipes are woefully inadequate to the demand flow. After you get a decent slope, bust out the end, and extend it to provide free-fall beyond your foundation. Can drop into a dry well and/or a French drain.

Joe

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Originally Posted by joe greiner

...............a French drain..........

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Quest Que Ce?

Mick

I think it what we call a "spoon drain"?

"Spoon drain" should work, too. Seems to be varying definition of "French drain." I had in mind a perforated, (usually) corrugated ABS pipe inside a gravel envelope, inside a wrap of filter cloth, all buried, except for gravel inlet basin and exposed outlet. Wikipedia has some discussion.

Joe

Mat

Yep - Depends on whether you have a gal box gutter or Zincalume. Since you said the house was built in 1964 it is highly unlikely to be zincalume (that was only created in 1972). I assumed it was the original gutter so would be galvanised iron. most probably with soldered joints (pop rivets were not all that common in 1964 either and there was no silicon sealer on the commercial market in Oz). Even using silicone sealer you must use the correct one - which are differently formulated for gal and zincalume!

So for a gal gutter keep aluminium flashings clear - lead or zinc is the go. Likewise you should not use zincalume in contact with gal either - as the galvanic reactions (electrolsysis) can cause problems too. Not fast and much slower in dry climates, but will significantly reduce the life of the product with the sacrificed coating.

There are v.good technical data sheets and FAQ on this subject at the BHP BlueScope Steel website:

http://www.bluescopesteel.com.au/go/...hnical-library


Often aluminium flashing has coatings that prevent or reduce contact - older types used tar-based finishes and then plastic. This can be used, but exposed metal at edges or where cut or damaged can still cause problems.

But as I said a 2-part waterproofing compound is probably the best if you can get good access and can clean and prepare before application. Or replace the gutter altogether - but if you do you need to account for the roofing material and follow the tech notes for the product you plan to use.

Re-read my earlier post and from others too - you have a series of issues to fix or minimise your problem - only one of which is the leaky box gutter: a) leaky gutter needs to be waterproofed or replaced; b) capacity of gutter needs to be sufficient; c) capacity of downpipes & stormwater drains needs to be sufficient; and d) you need to have a suitable overflow system to direct water away from the gutters and house in extreme rain or rain/hail events.

A number of posts have suggested how to deal with each.

A bit or work to do - but worth it to save damage to the house.

Bloss

Sorry on the delay. Thanks to everyone for their advice. It is a gal gutter and I have opened the end. The downpipe is 6in by 4in with a spitter. Also I have just laid all new storm water with one line designated just to the box gutter. There are two problems. The first in big storms the gutter cannot cope even though I have opened it up at the end. The other problem is it leaks several months after I seal it. I think I will investigate a two part waterproofer.

http://www.guttsa.com.au/ have a look at this link as they make a liner that goes in box gutters. think there in adelaide. nearly used it once to repair a box gutter but the boss said a $60 tin of bitumous paint was cheaper. gutter still leaks.

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Originally Posted by Woodbear

. . . . There are two problems. The first in big storms the gutter cannot cope even though I have opened it up at the end. The other problem is it leaks several months after I seal it. I think I will investigate a two part waterproofer.

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See my earlier post - use ponding boards/ sheets to increase the effective size of the gutter (if you can't simply replace it with a larger one which is likely to be problematic) THEN do the two-part waterproofing. Good luck - what you have done so far seems the right direction in any case.

Bloss

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Originally Posted by black1

http://www.guttsa.com.au/ ... nearly used it once to repair a box gutter but the boss said a $60 tin of bitumous paint was cheaper. gutter still leaks.

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:U

but the owner had the leaky gutter later on - the boss saved the money at the time

This looks like a good idea and product, but will not help the capacity problem of Mat's gutter.