Waterproofing polycarbonate sheets

Seb79 · 05-11-2019 12:37pm #1

Hi,

Just wondering if I could get some advice here. I got someone to build a 8 metre long by about 1 metre large shed at the side of our semi detached house. Everything was fine until it started raining of course. It is leaking at the sides and at some places in the middle as well. The guys who did the job simply don't give a dam and never came back to fix the issue.

The roof is made with polycarbonate sheets like these :https://www.diy.com/departments/ariel-clear-polycarbonate-twinwall-roofing-sheet-l-1-2m-w-610mm-t-4mm/241217_BQ.prd

The question is, what would be the best product to use to make this roof waterproof? Tried the strong tape for the sides which did make a small difference but it still leaks, also tried to put silicone a little everywhere where the water would go and again it did fix some spots but not all of it. I was then thinking on using some bituminus but was told that it will not work on polycarbonate sheets.

Any ideas? I don't fancy taking the all thing down after what it already cost me. The ideal would probably be taking the sheets down and putting wood with shed felt but I'd rather not go down that road if possible.

Thanks.

Idbatterim · 05-11-2019 12:48pm

Polycarbonate is water proof. Post up a photo...

You could try this

https://leadax.ie/building-contractors

garv123 · 05-11-2019 1:09pm

Seb79 wrote: »

Hi,

Just wondering if I could get some advice here. I got someone to build a 8 metre long by about 1 metre large shed at the side of our semi detached house. Everything was fine until it started raining of course. It is leaking at the sides and at some places in the middle as well. The guys who did the job simply don't give a dam and never came back to fix the issue.

The roof is made with polycarbonate sheets like these :https://www.diy.com/departments/ariel-clear-polycarbonate-twinwall-roofing-sheet-l-1-2m-w-610mm-t-4mm/241217_BQ.prd

The question is, what would be the best product to use to make this roof waterproof? Tried the strong tape for the sides which did make a small difference but it still leaks, also tried to put silicone a little everywhere where the water would go and again it did fix some spots but not all of it. I was then thinking on using some bituminus but was told that it will not work on polycarbonate sheets.

Any ideas? I don't fancy taking the all thing down after what it already cost me. The ideal would probably be taking the sheets down and putting wood with shed felt but I'd rather not go down that road if possible.

Thanks.

You haven't really said what bit is leaking. Is it leaking between the sheets, or down the sides where it meets a wall?

Idbatterim · 05-11-2019 1:12pm

garv123 wrote: »

You haven't really said what bit is leaking. Is it leaking between the sheets, or down the sides where it meets a wall?

I have the same issue. My dad put it up , so not getting into arguments over taking it down. Ours leaks in both places and I bet the op does too. Water will find a way!

garv123 · 05-11-2019 1:16pm

Idbatterim wrote: »

I have the same issue. My dad put it up , so not getting into arguments over taking it down. Ours leaks in both places and I bet the op does too. Water will find a way!

No offence meant to anyone, but just like any type of roof, if its not done right it will leak..

If I was the OP I would be getting the people who installed it back to fix it and seal it properly.

Idbatterim · 05-11-2019 1:17pm

garv123 wrote: »

No offence meant to anyone, but just like any type of roof, if its not done right it will leak..

If I was the OP I would be getting the people who installed it back to fix it and seal it properly.

Oh I one hundred percent agree. It’s only cause they aren’t done properly. I should have said water will find a way , if you give it the chance ...

05-11-2019 1:26pm

I'm a DIY'er, not a builder. Read my post with that in mind.

These sheets are generally overlapped on each other when they installed. There should be some silicone/caulk/tec7, whatever name you prefer to use, squeezed along the join of each sheet to prevent water from breaking through.

Where the sheets meet the side of the house/wall, there should again be a barrier, generally in the form of some lead flashing running along the join to prevent water getting in.

The plastic sheets would fall away from the house, and the 'curves' in the sheet should face away from the house (so the water runs down the roof and off the side, and doesn't 'pool' in the dips in the plastic sheeting). The roof shouldn't be perfectly flat/level.

The nails/screws used on the plastic should have a little piece of visible rubber around the tip of them, that prevents water accessing via the holes made by the nails/screws.

Your roof should look like this:

You'd really need to post a picture of the roof for people to give proper advice though.

Calahonda52 · 05-11-2019 1:31pm

KKK, the OP has a polycarbonate roof, not a corrugated one

we need pictures

listermint · 05-11-2019 1:35pm

Sounds like a lean too. Id put money on it having an inappropirate connection to the house envelope and their being sub standard roof drainaway.

Seb79 · 05-11-2019 4:06pm

Thanks so much guys. Yeah I agree, pictures are needed, will post these asap. For KKV, we are not talking about the same sheets, the one I have do not overlap each other. For GARV123, it is leaking between sheets and also sides where it meets the walls. And thanks Idbatterim I'll check that out that said it looks a little expensive but again might be a possibility.

Pictures to come, thanks again !

Seb79 · 05-11-2019 4:26pm

Here are some pictures hope this helps you help me

. As you can see the water actually stays on some of the sheets, I guess the angle is wrong as well..

garv123 · 05-11-2019 4:41pm

Seb79 wrote: »

Here are some pictures hope this helps you help me . As you can see the water actually stays on some of the sheets, I guess the angle is wrong as well..

That doesn't look like theres any angle at all, what direction is the water meant to flow?

Looks like a right cowboy job tbh.

Whats joining the sheets, did he use a joiner or overlap them?

Lumen · 05-11-2019 5:02pm

I slightly admire the ambition of creating a flat roof with polycarbonate sheets.

CJhaughey · 05-11-2019 7:08pm

There needs to be a fall, in one direction or the other.
That angled wood holding the cover over a pipe will also rot quickly seeing as its sitting in water and untreated.

the_pen_turner · 05-11-2019 9:24pm

unfortunitly thats a total disaster.
what is used for the flashing on either side (beside tubes of cheap silicone)
there needs to be proper flashing there and proper counter flashing installed on both sides. the caps would need to come off or cut under to fold the lead in under them then sealed.
it looks like the sheets are just overlapped. the plastic will flex behind where they are overlapped and lift the end allowing in water.those sheets arnt designed to be extended lenthwise like that. the middle is pulled down too much creating a pool for water. you could open those tech screws and put in a strip of wood to support the plastic.

im not sure what to say about that little angled bit on top. thats just so bad you have to laugh

realistically the whole roof should be falling away from the house into a gutter along the wall

GolfNut33 · 05-11-2019 9:36pm

Wow...what a really poor job. The whole thing needs to come down and redone properly. No point running amok with silicone if the whole structure is inherently flawed.

Lumen · 06-11-2019 9:49am

FWIW it is possible to buy large continuous polycarbonate sheets in Ireland.

A quick google found them in lengths of up to 7m.

So there's really no excuse for all those joins.

Seb79 · 06-11-2019 9:54am

Thanks guys. Where I was standing when I took the picture is where the gutter is. There is an angle as the end where I was standing is 230 cm height and the other end is 235. They did use the joining strip to join the sheets together but again, was that done properly...

I really appreciate your answers. I'd love to fix it myself, something I probably should have done from the start when I see the result here...

"realistically the whole roof should be falling away from the house into a gutter along the wall" , I agree with that but the way it is built will make it difficult for me to fix.

I'm not sure what I'll do but the sheets will come down at some stage. Might replace them with the corrugated ones that overlap each others but I have the feeling this will not fix the leaking on the side where it meets the house wall. Covering the lot with wood might be my best option (and I can then make a better angle) and then put some roofing felt on top of it like that I can use that liquid rubber to seal the sides. I can't use that liquid on plastic sheets from what I understand so that won't work if I cover the lot with corrugated sheets.

Thanks again

Seb79 · 06-11-2019 10:04am

Ho thanks Lumen, really didn't know that. As far as I know they got all their stuff in B and Q.

the_pen_turner · 06-11-2019 10:05am

Can you get a better pic of the joint bars. .
What is the flashing on the side made of. Have you a closer pic of that angled bit on top

Seb79 · 06-11-2019 10:22am

the joint bars, you mean where 2 sheets of polycarbonate meets? As for the flashing, I guess you mean the tape at the side of the house? if so it is something like this one: https://www.diy.com/departments/roof-pro-grey-flashing-tape-l-10m-w-150mm/1932763_BQ.prd but as it was still leaking after they left I tried with some silicone and hoped for the best...

not sure what picture you are looking for, which angled bit? the thing at the left side on top of the sheet against the wall? That thing is for the extraction fan from the kitchen next door.

GreeBo · 06-11-2019 10:27am

In fairness there does seem to be a bit of a fall on it, but not enough to overcome the sagging and the crappy joints so you have standing water.
Those joints are never going to survive standing water...

What is under the little wooden box on the left?
Please tell me its not a flue for your boiler or something?!

Seb79 · 06-11-2019 10:31am

that box is for the steam. The cooker is right on the other side of the wall. The hole for the smoke/steam is inside the shed so they made that little box to cover the tube so that the rain doesn't go in...

GreeBo · 06-11-2019 10:34am

Seb79 wrote: »

that box is for the steam. The cooker is right on the other side of the wall. The hole for the smoke/steam is inside the shed so they made that little box to cover the tube so that the rain doesn't go in...

Just to clarify, its the outlet for a kitchen extractor/hood?

Seb79 · 06-11-2019 10:35am

Yes it is

Mango Joe · 06-11-2019 10:38am

Lumen wrote: »

I slightly admire the ambition of creating a flat roof with polycarbonate sheets.

The absolute cretins posing as legitimate tradesmen that carried out this ridiculously poor job seem to have been trying to create some sort of an elevated reflecting pool.

Sadly they're off doing this to someone else's house right now and getting well paid for it.

I understand the legal issues around posting their name, company name and phone number on here.... But really its such a pity that posters cannot put up photos like this and then state the name of who did it without anything else needing to be said - It would be plenty for people to draw their own conclusions.

OP I think the small claims court might award you enough compensation for a repair to be effected?

I'd imagine that if you took photos of all that standing water and video clips actually showing water running in and so on then any judge would take about 25 seconds to award in your favour.

GreeBo · 06-11-2019 10:41am

Mango Joe wrote: »

The absolute cretins posing as legitimate tradesmen that carried out this ridiculously poor job seem to have been trying to create some sort of an elevated reflecting pool.

Sadly they're off doing this to someone else's house right now and getting well paid for it.

I understand the legal issues around posting their name, company name and phone number on here.... But really its such a pity that posters cannot put up photos like this and then state the name of who did it without anything else needing to be said - It would be plenty for people to draw their own conclusions.

I guess the OP could leave a YELP (etc) review and post a link to that?

the_pen_turner · 06-11-2019 10:47am

Seb79 wrote: »

the joint bars, you mean where 2 sheets of polycarbonate meets? As for the flashing, I guess you mean the tape at the side of the house? if so it is something like this one: https://www.diy.com/departments/roof-pro-grey-flashing-tape-l-10m-w-150mm/1932763_BQ.prd but as it was still leaking after they left I tried with some silicone and hoped for the best...

not sure what picture you are looking for, which angled bit? the thing at the left side on top of the sheet against the wall? That thing is for the extraction fan from the kitchen next door.

Yes the bars where the sheets meet.

That's flash band. Surely they didn't use that there. .

How is the little part for the extractor sealed.

Mr Tickle · 06-11-2019 10:51am

Seb79 wrote: »

Thanks guys. Where I was standing when I took the picture is where the gutter is. There is an angle as the end where I was standing is 230 cm height and the other end is 235. They did use the joining strip to join the sheets together but again, was that done properly...

I really appreciate your answers. I'd love to fix it myself, something I probably should have done from the start when I see the result here...

"realistically the whole roof should be falling away from the house into a gutter along the wall" , I agree with that but the way it is built will make it difficult for me to fix.

I'm not sure what I'll do but the sheets will come down at some stage. Might replace them with the corrugated ones that overlap each others but I have the feeling this will not fix the leaking on the side where it meets the house wall. Covering the lot with wood might be my best option (and I can then make a better angle) and then put some roofing felt on top of it like that I can use that liquid rubber to seal the sides. I can't use that liquid on plastic sheets from what I understand so that won't work if I cover the lot with corrugated sheets.

Thanks again

Again, I'm a DIYer rather than builder so bear that in mind.
That angle just isn't nearly steep enough. OR rather not consistent enough. The fact that there are large puddles on each sheet proves that. You can even see the curve in the second last sheet .
There's nothing wrong with the sheets that you have really. Replacing them with corrugated stuff or plywood and felt won't solve the problem.

What it looks like to me is that each of these sheets is mounted too flat so they're dipping in the middle and filling with water. then it's flowing in under the flashing that you have against each wall. No amount of silicone is going to stop the water if it's pooled there constantly.

The idea with flashing is usually to have the water land on it, then run down a roof that slopes away from it. In other words to have the "fall" of the roof run perpendicular to the flashing as opposed to parallel.

As someone else suggested, the correct solution is to take it down and re-build it with a slope from the house to the wall and a piece of guttering on that end to carry the water away.

Warning: Dubious advice to follow!
If you were absolutely determined to have it drain lengthwise as it is now then you could flex each sheet downwards in the middle. Effectively turn the whole thing into one long gutter.

Either way they did a bad job day one and it's not fixable without a lot of work. Sorry

Seb79 · 06-11-2019 12:36pm

Mango Joe wrote: »

The absolute cretins posing as legitimate tradesmen that carried out this ridiculously poor job seem to have been trying to create some sort of an elevated reflecting pool.

Sadly they're off doing this to someone else's house right now and getting well paid for it.

I understand the legal issues around posting their name, company name and phone number on here.... But really its such a pity that posters cannot put up photos like this and then state the name of who did it without anything else needing to be said - It would be plenty for people to draw their own conclusions.

OP I think the small claims court might award you enough compensation for a repair to be effected?

I'd imagine that if you took photos of all that standing water and video clips actually showing water running in and so on then any judge would take about 25 seconds to award in your favour.

I really don't want to go down that road, the guys have been recommended to me by a neighbour and to be honest I don't want to start some legal stuff, I'd rather keep the peace with my neighbours.

Thank you all for your inputs here, it is really appreciated. I'll let the winter pass and will sort this out after.

GreeBo · 06-11-2019 12:41pm

Seb79 wrote: »

I really don't want to go down that road, the guys have been recommended to me by a neighbour and to be honest I don't want to start some legal stuff, I'd rather keep the peace with my neighbours.

Thank you all for your inputs here, it is really appreciated. I'll let the winter pass and will sort this out after.

Expect your problems to increase significantly if we get snow.
Standing water = standing snow = lots of water coming in.

Idbatterim · 06-11-2019 12:45pm

I see what they were trying to do. The fall simply isn’t enough. You would need at least ten cm for that length , ideally more like 15

GreeBo · 06-11-2019 12:51pm

Idbatterim wrote: »

I see what they were trying to do. The fall simply isn’t enough. You would need at least ten cm for that length , ideally more like 15

For a space like that a fall from left to right is usually much more preferable than from front to back, you need less of a height reduction and also, typically, it means water is running with joints rather than across them.

Of course this means a longer gutter but its a better job.

OP no matter what you do you will have water in that space as its going to run down both external walls into your new space.
Even with the best flashing in the world, the wall itself isnt water proof.

Idbatterim · 06-11-2019 12:55pm

GreeBo wrote: »

For a space like that a fall from left to right is usually much more preferable than from front to back, you need less of a height reduction and also, typically, it means water is running with joints rather than across them.

Of course this means a longer gutter but its a better job.

OP no matter what you do you will have water in that space as its going to run down both external walls into your new space.
Even with the best flashing in the world, the wall itself isnt water proof.

Yeah agreed. If day they did it for speed purposes the way they did it. Not a good job. Not putting in even near enough fall is a disgrace if that’s what they do for a living !

CJhaughey · 06-11-2019 12:58pm

The fall realistically should run across the roof, toward the wall between yourself and the neighbours.
On the wall itself you can mount a gutter running back to a drain.
The way it is now is only a botched job, I can't see a way to fix it without removing all the panels and re-doing the joists with the correct fall and installing a gutter along the wall.

garv123 · 06-11-2019 1:03pm

Seb79 wrote: »

I really don't want to go down that road, the guys have been recommended to me by a neighbour and to be honest I don't want to start some legal stuff, I'd rather keep the peace with my neighbours.

Thank you all for your inputs here, it is really appreciated. I'll let the winter pass and will sort this out after.

Have you tried ringing the person who did the job? Im sure your neighbors wouldn't be leaving him off if that mess was on their property.
Somethimes just the mention of legal action can make them get the finger out.

You're gonna have a lot of money gone to waste if you dont do anything about it

Calahonda52 · 06-11-2019 1:53pm

No wonder HE wept!.

Op the other issue here is that the ends of the sheets were not sealed so the water thats already in the cells is there for life and will eventually go black as it heated and cooled..
What is the triangular item in aid of?

Mango Joe · 06-11-2019 1:56pm

Seb79 wrote: »

I really don't want to go down that road, the guys have been recommended to me by a neighbour and to be honest I don't want to start some legal stuff, I'd rather keep the peace with my neighbours.

Thank you all for your inputs here, it is really appreciated. I'll let the winter pass and will sort this out after.

Jesus....Look you seem like a nice person and all but.....

1. This idiot Neighbour needs to STFU with their terrible recommendations.
2. This Builder needs to go back to their real job in McDonalds.

And you Sebastian shouldn't be seriously out of pocket while cycling a rusty bike around in your damp clothes all brought about by that calamity hastily tacked onto the side of your house by assholes.

Seriously - grow a pair.

BarryD2 · 06-11-2019 2:03pm

GreeBo wrote: »

Expect your problems to increase significantly if we get snow.
Standing water = standing snow = lots of water coming in.

That's what I thought too - not just water, but any decent dump of snow could see the whole lot cave in!

listermint · 06-11-2019 2:12pm

This is salvageable using alot of the existing components.

But.

It has to come down.

What i would do is take the flashing off entirely. Remove the poly too. Then start from scratch. Put up the first highest sheet in place Cut out the render and put in new flashing for that bit into the render and over the ploy.

move down on to the next sheet. And same again. But rather than joining them uniformly like they have done. I would drop the next sheet under the first overlapping by about 100mm. So water falls down (all sheets on a slope minimum half inch per 5 ft)

Continue on down until all sheets are flashed in and all sheets are staggered under the last.

This would solve the wall to roof problem and solve the joint too. because lets face it joining these as they are or anything like it on the flat wont work. Waste of time.

BeardySi · 06-11-2019 2:19pm

Seb79 wrote: »

I really don't want to go down that road, the guys have been recommended to me by a neighbour and to be honest I don't want to start some legal stuff, I'd rather keep the peace with my neighbours.

You're taking the cowboy to court not your neighbour.

If they're family or a friend of the neighbour, get them to have a word - it was the neighbour that recommended them after all.

If they're just a random "builder" they found - SCC time. Its no skin off the nose of your neighbour. Can't see a reason you'd fall out with them over it.

07-11-2019 6:56pm

I'm not sure how much those sheets cost, but it mightn't be the worst idea in the world to just build a roof over the roof you already have.

You'd just have to angle it so it falls towards the boundary wall, and run a gutter on the lower side (at the boundary wall) and into the existing gutter that's already been set up.

So you'd effectively have two roofs there, but it'd be probably cheaper than removing that roof and fixing it.

Twister2 · 07-11-2019 7:43pm

Deleted User wrote: »

I'm not sure how much those sheets cost, but it mightn't be the worst idea in the world to just build a roof over the roof you already have.

You'd just have to angle it so it falls towards the boundary wall, and run a gutter on the lower side (at the boundary wall) and into the existing gutter that's already been set up.

So you'd effectively have two roofs there, but it'd be probably cheaper than removing that roof and fixing it.

wouldn't it look sh1T though from the inside

i'll wager there was no checks or receipts involved here so no use complaining after

Calahonda52 · 07-11-2019 7:54pm

listermint wrote: »

This is salvageable using alot of the existing components.

But.

It has to come down.

What i would do is take the flashing off entirely. Remove the poly too. Then start from scratch. Put up the first highest sheet in place Cut out the render and put in new flashing for that bit into the render and over the ploy.

move down on to the next sheet. And same again. But rather than joining them uniformly like they have done. I would drop the next sheet under the first overlapping by about 100mm. So water falls down (all sheets on a slope minimum half inch per 5 ft)

Continue on down until all sheets are flashed in and all sheets are staggered under the last.

This would solve the wall to roof problem and solve the joint too. because lets face it joining these as they are or anything like it on the flat wont work. Waste of time.

Why not start at the lowest, like roof tiles?

07-11-2019 10:31pm

Twister2 wrote: »

wouldn't it look sh1T though from the inside

i'll wager there was no checks or receipts involved here so no use complaining after

I'd rather be dry looking at two roofs, than soaked looking at one.

listermint · 08-11-2019 9:22am

Calahonda52 wrote: »

Why not start at the lowest, like roof tiles?

No reason, yours is the best approach. I wrote that in a rush. Bottom to top.

You're correct

GreeBo · 08-11-2019 12:42pm

Calahonda52 wrote: »

Why not start at the lowest, like roof tiles?

The only reason to start from the top is that access will be much easier, you can possibly do it from a ladder on the ground, if you start at the lowest then you need some way to get up onto the roof without standing onthe previous level

Lumen · 08-11-2019 12:45pm

There's probably a bathroom window the OP can abseil out of. :pac:

Seb79 · 09-11-2019 8:37am

Deleted User wrote: »

I'm not sure how much those sheets cost, but it mightn't be the worst idea in the world to just build a roof over the roof you already have.

You'd just have to angle it so it falls towards the boundary wall, and run a gutter on the lower side (at the boundary wall) and into the existing gutter that's already been set up.

So you'd effectively have two roofs there, but it'd be probably cheaper than removing that roof and fixing it.

Thanks. Yeah I was thinking on building a roof over the roof as you said instead of taking the all thing down.

Thanks again for all you help guys much appreciated. This gave me a lot to think about

I'll post some pictures once I'm finished with it, it will take me a while but I'll get there eventually.

And sorry if I didn't answer all posts or added some pictures that you requested mainly the joint between 2 sheets as this would mean taking the tape off which I rather not do as it will make it worse.

Have a great weekend!

BryanF · 11-11-2019 1:33pm

Waterproofing polycarbonate sheets

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