zincalum sheet metal roof leaks ... what to do ?

[steven100]

Hi all,   House built 5 years ago …    and I'm so angry that they just let this go on and do NOTHING. !!

The MIL house has around 4 or 5 places that water has leaked through the zincalum sheet roof and partially started to destroy the ceiling ( I assume gyprock )

which will have to be replaced.

Anyway, whats the best method to fix these 4 spots that are showing leaks.

Do I get up on the roof and silicon dozens of roof screws each side where I think the leak is coming from ???

Is Silicon ok ??  black  ???

Do I get a builder to silicon every roof screw  ???

 

Thanks,  

[sometimewoodworker]

Our roof was leaking through the screw holes a few years ago. I fixed it by covering each screw with a square of aluminium backed bitumen. This has been in place for over 10 years without leaking again.

[Kwasaki]

If the roof screws in those areas are in the flat valley part of the roof sheet then take out the roof screw make sure it's dry and put high quality roof silicone sealant into the hole and refix.

If there are roof sheet laps at these areas then lift and reseal the laps and put back fixings as previously said.   

[shaemus]

18 hours ago, steven100 said:

Hi all,   House built 5 years ago …    and I'm so angry that they just let this go on and do NOTHING. !!

The MIL house has around 4 or 5 places that water has leaked through the zincalum sheet roof and partially started to destroy the ceiling ( I assume gyprock )

which will have to be replaced.

Anyway, whats the best method to fix these 4 spots that are showing leaks.

Do I get up on the roof and silicon dozens of roof screws each side where I think the leak is coming from ???

Is Silicon ok ??  black  ???

Do I get a builder to silicon every roof screw  ???

 

Thanks,  

You should attempt to the best of your ability to find the exact point which the leak is coming from.

 

Silicon is ok to use, BUT buy a decent brand and roofing grade. you can buy sika flex from Most large DIY stores and online. The stuff that is available here is Made in China and not as trustworthy as the same product made  elsewhere. 

 

you will be able to see where the water has come through as the roof sheet will show some kind of water damage / stains. 

 

if the Plasterboard (gypsum) is stained then once dry you may be able to re paint. it may well be cement board  to which the  same applies.

 

The roofing screws should have been installed with a epdm rubber washer which gets compressed against the roof sheet. they may be distorted which is why they are not sealing properly. they are very easy to remove, if you remove one try and buy a larger size to replace what you have removed. if you can't be bothered to do that then. ( do you best silicon the rest)

 

If the leak point are obvious then you are lucky. 

 

Some images would be helpfull if you get stuck

 

shaemus

[Don Chance]

You need to understand the metal roofs are a bad choice because metal expands and contacts a great deal with heat. This causes the fasteners to get pulled out eventually, widened and leak.

 

So first off i would consider changing the roof to clay or even tar shingles.

The way any roof should be designed is as a double roof. So you have the first roof or metal if you wish, then build a second roof over it with about a 6" gap. This will have a cooling effect too. This way if your first roof leaks it won't destroy your house. It is also easy to replace in the future.

 

A metal roof should have no exposed fasteners. If they are exposed they should have rubber grommets around them.

 

Another solution is paint the roof with a white vinyl coating that is stretchable. Then it won't leak but you will need to repainted ever few years. The white will reflect heat too.

Edited July 29, 2019 by Don Chance

[UncleMhee]

Excellent info regarding the sealing of screws and laps (joins) above. However as a retired plumber one of the main causes of leaking roofs is a failure to turn up the flats that reside under the ridge capping.

I have yet to see a Thai builder do it, despite numerous attempts of explaining the reasoning behind my requests. In fact it brings forth great mirth that a farang actually thinks failure to do so will result in a water fall into the ceiling cavity.

Nonetheless, that is the result and it is part of Queensland's building code to alleviate water ingress; especially during cyclones and other heavy weather events.

[sometimewoodworker]

3 hours ago, UncleMhee said:

I have yet to see a Thai builder do it, despite numerous attempts of explaining the reasoning behind my requests. In fact it brings forth great mirth that a farang actually thinks failure to do so will result in a water fall into the ceiling cavity.

So they don't do this?

[sometimewoodworker]

3 hours ago, Don Chance said:

So first off i would consider changing the roof to clay or even tar shingles.

The way any roof should be designed is as a double roof. So you have the first roof or metal if you wish, then build a second roof over it with about a 6" gap. This will have a cooling effect too. This way if your first roof leaks it won't destroy your house. It is also easy to replace in the future.

Double roof, totally unnecessary double expense.

 

Tar shingles need a wood sheeting under if you can get them and provide a good food source for termites.

3 hours ago, Don Chance said:

You need to understand the metal roofs are a bad choice because metal expands and contacts a great deal with heat. This causes the fasteners to get pulled out eventually, widened and leak.

Again BS as people with correctly fitted metal roofed structures will find.

[Don Chance]

31 minutes ago, sometimewoodworker said:

Double roof, totally unnecessary double expense.

 

Tar shingles need a wood sheeting under if you can get them and provide a good food source for termites.

Again BS as people with correctly fitted metal roofed structures will find.

A double roof insures ventilation of the roof, which will extend it's life. Also prevents leaks as the OP experienced. Which means he would have saved money on repairing the interior. Also when want to replace the roof, it is a much easier job. Keeps the roof cool. So many benefits which maybe worth the extra cost to some.

Actually Thai's have been using double roofs for a long time.

[eyecatcher]

I dont agree at all with Donchance saying expansion will pull out fasteners.

A typical profiled roof sheet  has an extra 150mm of expansion room in the profile in which to take up any slack.

In the sun expansion will take the easiest route, so the joint of a gutter is susceptable every time, on a sheet the unfixed ridges have loads of scope to move without bothering the screws.

 

Your sheets should always be fixed from the high point of the profile to minimise those leaks, screwing in the trough means you get all the rain passing over them.

This is the screw fixing needed which had been mentioned by others

[malt25]

20 hours ago, Don Chance said:

You need to understand the metal roofs are a bad choice because metal expands and contacts a great deal with heat. This causes the fasteners to get pulled out eventually, widened and leak.

 

So first off i would consider changing the roof to clay or even tar shingles.

The way any roof should be designed is as a double roof. So you have the first roof or metal if you wish, then build a second roof over it with about a 6" gap. This will have a cooling effect too. This way if your first roof leaks it won't destroy your house. It is also easy to replace in the future.

 

A metal roof should have no exposed fasteners. If they are exposed they should have rubber grommets around them.

 

Another solution is paint the roof with a white vinyl coating that is stretchable. Then it won't leak but you will need to repainted ever few years. The white will reflect heat too.

"You need to understand the metal roofs are a bad choice"  Really !  I wonder why all the metal roofed houses in tropical Australia don't leak ?

[sometimewoodworker]

18 hours ago, Don Chance said:

A double roof insures ventilation of the roof, which will extend it's life. Also prevents leaks as the OP experienced. Which means he would have saved money on repairing the interior. Also when want to replace the roof, it is a much easier job. Keeps the roof cool. So many benefits which maybe worth the extra cost to some.

Actually Thai's have been using double roofs for a long time.

Again talking more disinformation  as most of the rest of what you have posted also seems to be.

 

Double roofed buildings are an extreme rarity now as they are significantly more than double the complexity and cost of a single roof, modem construction and installation makes them redundant, they are vastly more expensive to repair as you not only have to waterproof the first one but also all the support penetrations for the second one.

 

Virtually all the buildings you see that seem to have double roofs don't, the under roof isn't complete and is a cosmetic feature. The ones you show are probably like this but you have carefully chosen a view that doesn't prove the point either way.

Edited July 30, 2019 by sometimewoodworker

[tjo o tjim]

Peak vs valley of the panel attachments should not matter with the correct screws shown above. Also make sure the problem isn’t really condensation, since vapor barriers (and insulation) are often omitted here. 

Edited August 1, 2019 by tjo o tjim

[sometimewoodworker]

2 hours ago, tjo o tjim said:

Peak vs valley of the panel attachments should not matter with the correct screws shown above. Also make sure the problem isn’t really condensation, since vapor barriers (and insulation) are often omitted here. 

The screws shown above are specifically for peak fixing, valley fixing screws do not have the thread interruption and are usually shorter.

[eyecatcher]

On 8/1/2019 at 9:33 AM, tjo o tjim said:

Peak vs valley of the panel attachments should not matter with the correct screws shown above. Also make sure the problem isn’t really condensation, since vapor barriers (and insulation) are often omitted here. 

It does make a difference as the weak point on the screw is the rubber washer which will perish (at some point)

When that happens fixings in the trough get 100% of the rainfall passing over them, a place also more likely to clog with leaves.

 

Condensation, I have never seen any here ever. There simply are not the extremes of hot and cold to make it an issue. Anyone else experienced condensation here, besides on the outside of a glass of beer?

[sometimewoodworker]

3 hours ago, eyecatcher said:

Condensation, I have never seen any here ever. There simply are not the extremes of hot and cold to make it an issue. Anyone else experienced condensation here,

Sometimes on the outside of single glazed windows, and occasionally on car windows in the early morning.

[eyecatcher]

5 hours ago, sometimewoodworker said:

Sometimes on the outside of single glazed windows, and occasionally on car windows in the early morning.

Ah yes, on the car windscreen at 5am in January when we (us in Chiang Mai) had to go to imnigration to form a queue for the 9am visa extension tickets.

thanks for reminding me...

[Artisi]

On 7/30/2019 at 7:35 AM, malt25 said:

"You need to understand the metal roofs are a bad choice"  Really !  I wonder why all the metal roofed houses in tropical Australia don't leak ?

Simply installed correctly, short-cut Somchai wasn't involved 

[shaemus]

On 8/2/2019 at 9:42 AM, eyecatcher said:

 

Condensation, I have never seen any here ever. There simply are not the extremes of hot and cold to make it an issue. Anyone else experienced condensation here, besides on the outside of a glass of beer?

i have a colorbond roof and i regularly get condensation forming on the roof and down  to the Gutters, daily depending on the weather