Can sika bond to sika

[YoungDave]

Hello fun,

So made it to Italy today after a couple of amazing weeks in Switzerland, but it's pretty stormy and I've picked up a leak where I installed a maxxfan in place of an old rooflight. I (thought I) sealed up extremely well with sika, but clearly not.

I am hoping I can go over the whole seal again with another layer of sika...? I guess the question is does it bond to itself? Or do I need to take it out, clean it up, and seal again from scratch.

Thanks and all the best,
YoungDave

 

[CazPaul]

That the problem with using Sika, you really need to remove it to do a proper job, clean all surfaces and apply fresh sealant.

Using Sika has made this a very hard task, you should have used non setting sealant such as Hodgsons Seamseal CV.

I would stick some strong waterproof duct tape around or Vaseline around for now, that should stop the leak temporarily.

 

[jollyrodger]

Did you just use sika or screw it as well?

 

[Mikeco]

I’ve used Sika over an existing fitted roof light, just make sure that the original is clean and dry.

 

[YoungDave]

CazPaul noted. Lesson learnt there for sure.

jollyrodger - for better or worse - just sika.

Mikeco I'll give it a go in that case and then revert to alternaties if necessary.

Thanks guys, will keep you posted how I go,
YoungDave

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[Terry]

Sika does not stick to some plastics Use Puraflex 40 or the Hodgsons you will have to remove,clean and refit

 

[YoungDave]

Terry uh oh that definitely doesn't sound good. Okay, noted, thank you

 

[Landy Andy]

Yes. Sika will stick to Sika

 

[Terry]

Yes. Sika will stick to Sika

Yes but the Sika is not sticking to the plastic hence the leak may well stick some more on as a temp fix

 

[Landy Andy]

Yes but the Sika is not sticking to the plastic hence the leak may well stick some more on as a temp fix

Yes. But I’m answering the question.
And do we know the sika is not sticking to the plastic?

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[Terry]

Ok point taken

 

[Lenny HB]

With Sika you have to use the right type of Sika and which one depends on the type of plastic, too late now.

You could seal it with silicon until you get home. Easy to get and when you get home easy to clean off with silicon remover.
If you can find a car accessory shop some Clear RTV Silicon would make a good repair you can get it in tubes so you don't need a gun to apply it.

 

[olsgreen]

Yes, it will stick. I've just replied to another post about Sika, then spotted this one.

Which Sikaflex for holding something to the roof

Hi all I have a 4G aerial to fit on the roof - other than having to drill through with is rather daunting! I am not 100% sure which is the best Sikaflex for sticking it down and sealing around the edge of it. Ive got a tube of 221 and 512 - any recommendations which to use and why.... Thanks

www.motorhomefun.co.uk

Sika does not stick to some plastics Use Puraflex 40 or the Hodgsons you will have to remove,clean and refit

Too right, just mentioned that in the post above. Some plastics have residue when they come out of manufacture that prevents bonds forming, need to clean it with isopropyl before applying Sika.

Using Sika has made this a very hard task, you should have used non setting sealant such as Hodgsons Seamseal CV.

I was advised by Hodgsons NOT to use seamseal in any areas that could be prone to standing water, which on my van would make it a bad choice for use for the Maxfann as it's on a flat section of the roof.

Yes but the Sika is not sticking to the plastic hence the leak may well stick some more on as a temp fix

I used Sika on my Maxxfan (following the above), it's stuck like rock.

 

[CazPaul]

Yes, it will stick. I've just replied to another post about Sika, then spotted this one.

Which Sikaflex for holding something to the roof

Hi all I have a 4G aerial to fit on the roof - other than having to drill through with is rather daunting! I am not 100% sure which is the best Sikaflex for sticking it down and sealing around the edge of it. Ive got a tube of 221 and 512 - any recommendations which to use and why.... Thanks

www.motorhomefun.co.uk

Too right, just mentioned that in the post above. Some plastics have residue when they come out of manufacture that prevents bonds forming, need to clean it with isopropyl before applying Sika.



I was advised by Hodgsons NOT to use seamseal in any areas that could be prone to standing water, which on my van would make it a bad choice for use for the Maxfann as it's on a flat section of the roof.



I used Sika on my Maxxfan (following the above), it's stuck like rock.

Surely you shouldnt have standing water on any roof,be it house, shed, garage or motorhome, its a recipe for disaster. Need to drive it slightly up chocks so water runs off, if water just sits on any roof for days, weeks on end you will have problems. If water is pooling then its terrible design or park if differently?

OP doesnt mention his roof fan is subject to standing water.

 

[Riverbankannie]

Surely you shouldnt have standing water on any roof,be it house, shed, garage or motorhome, its a recipe for disaster. Need to drive it slightly up chocks so water runs off, if water just sits on any roof for days, weeks on end you will have problems. If water is pooling then its terrible design or park if differently?

OP doesnt mention his roof fan is subject to standing water.

If you have a Ducato roof then there is always standing water in the channels, up against the various roof lights Doesn’t matter if you park it nose down, nose up or sideways. Not only that but there is a large amount of sealant as the roof lights straddle the channels.

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[CazPaul]

If you have a Ducato roof then there is always standing water in the channels, up against the various roof lights Doesn’t matter if you park it nose down, nose up or sideways. Not only that but there is a large amount of sealant as the roof lights straddle the channels.

it would be interesting to see what the professional converters use, the ones i have spoken to say they use the tape to stick the rooflights down although they may use a board of some sort first to raise the height. I still maintain anything you may have to replace, windows, rooflights etc you should use non setting sealant. I presume there isnt standing water just sat up againt the rooflight sealant all the time, they surely would have to raise the height and the standing water, if there is any, will be sat up against the raised board. The roof light is then sat on top of the board.

On our Murvi Morello they used a square board to raise the height first and get a level surface. I replaced the bathroom rooflight, as it was cracked, on our Murvi and used seamseal. Some of them take a bit of removing as it is using a non setting sealant, i wouldn't like to attempt it with a Sika bonded one.

 

[olsgreen]

Surely you shouldnt have standing water on any roof,be it house, shed, garage or motorhome, its a recipe for disaster. Need to drive it slightly up chocks so water runs off, if water just sits on any roof for days, weeks on end you will have problems. If water is pooling then its terrible design or park if differently?

OP doesnt mention his roof fan is subject to standing water.

I completely agree that it's a recipe for disaster and that measure should be taken to counter it. However, there is still a high potential. I would say most would get pooling of some level, maybe not feet deep but not straight run off. Our roof pools from time to time (c class), we don't always get the chocks out if we're only staying for the night.

it would be interesting to see what the professional converters use, the ones i have spoken to say they use the tape to stick the rooflights down although they may use a board of some sort first to raise the height. I still maintain anything you may have to replace, windows, rooflights etc you should use non setting sealant. I presume there isnt standing water just sat up againt the rooflight sealant all the time, they surely would have to raise the height and the standing water, if there is any, will be sat up against the raised board. The roof light is then sat on top of the board.

On our Murvi Morello they used a square board to raise the height first and get a level surface. I replaced the bathroom rooflight, as it was cracked, on our Murvi and used seamseal. Some of them take a bit of removing as it is using a non setting sealant, i wouldn't like to attempt it with a Sika bonded one.

The professional converters / repairers I've spoken to use a range, I got a different answer from different companies, they all favour different brands and different systems.

I removed and re-bedded our Sika bonded skylight, although I'd admit it was not easy, it came out and cleaned up fine. I'd rather have something bonded and sealed to the maximum that's more of a chore to get out than to just use a sealant just for ease of removal should the need arise later.

When installing our Maxxfan I used W4 tape bedding mastic underneath the hood and then sealed the edges and screw heads/holes with Sika 512.

 

[Skipper43]

Have a look at Dekasyl. They have a website (Dekalin?) which informs you how to make non-stick items prepared for their product.

 

[Terry]

I have been converting vans over 20 years and been given all sorts to try from different suppliers and different converter's.
Yes the butal tape works for a time as does Sikaflex BUT they both let go after a while,fact.
I don't know if it's down to water freezing, melting then re-feezing ( one of the theory s)? I do know that they use the tape in factory because it's clean to use and they don't get someone with sealent on overalls climbing in and out of vans etc,
I do know I have used Puraflex 40 (same company as Sikaflex-half price) for the last 8/10 ish years with out problem. I also found Siromer grip and grab adhesive that works greatonce this is pressed in place it is not coming off Take what you want from this information but I know what works for me Glues have come a long way over the last 20 year's

 

[Riverbankannie]

it would be interesting to see what the professional converters use, the ones i have spoken to say they use the tape to stick the rooflights down although they may use a board of some sort first to raise the height. I still maintain anything you may have to replace, windows, rooflights etc you should use non setting sealant. I presume there isnt standing water just sat up againt the rooflight sealant all the time, they surely would have to raise the height and the standing water, if there is any, will be sat up against the raised board. The roof light is then sat on top of the board.

On our Murvi Morello they used a square board to raise the height first and get a level surface. I replaced the bathroom rooflight, as it was cracked, on our Murvi and used seamseal. Some of them take a bit of removing as it is using a non setting sealant, i wouldn't like to attempt it with a Sika bonded one.

Whatever they used it remained soft and stickyish for some time as it now has a layer of embedded tree twigs and seeds stuck in it from the silver birches outside our house.

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[olsgreen]

Yes the butal tape works for a time as does Sikaflex BUT they both let go after a while,fact.

I think that very much depends on WHICH Sikaflex you use, for which purpose. If that's true of them all, I'm screwed, I resealed my entire roof with Sikaflex 521UV.

One thing I do know about adhesives and sealants, everyones got their own favourites, experiences and opinions on them.

 

[Deneb]

Whatever they used it remained soft and stickyish for some time as it now has a layer of embedded tree twigs and seeds stuck in it from the silver birches outside our house.

Sounds like Seamseal or similar. It's a non-setting sealant that forms a tacky semi-setting surface, although Hodgsons say that it does not skin over. My van is the same, and they use plenty of it for good measure, but the sealant is only really used to fill the edge gaps as the main sealing is done by filling the roof channels and then building up a level platform with mastic strip, which is compressed under the fixings for the heki or whatever, and sealant then run around the edge.

It's dead easy to work with if you need to replace the component, as you can clean it up in no time with white spirit and bed in new mastic strip and sealant easily.

The data sheets does say to avoid using Seamseal within joints that are prone to habouring or trapping standing water, but as applied on my van it's not within the joint, just forming the outer skin. The inside of the joint is sealed with the compressed mastic strip. If done correctly, there is no water trapped within the joints and although certain areas allow standing water during and after rain, they dry again shortly afterwards unless you live in a constant monsoon environment.

For joints that only utilise sealant for weatherproofing I use Hodgsons Silfix U9.

 

[YoungDave]

Hi Everyone, thanks for the info. So for the simple reason I didn't fancy adding MORE holes to my roof when fitting the maxxfan, I just used sika, no screws. I'm pretty sure it can bond to the plastic because it's rock solid (or as solid as sika gets).

I removed the internal vanity flange to allow the damp to dry out, and we had another thunderstorm but there was no ingress. When it leaked it was a pretty special alpine storm (we were seriously worried about flash flooding).

Anyway, given we are still planning to continue travelling away from the UK rather than towards it, I'm going to try adding some more sika to anywhere that looks suspicious/everywhere, and see where I get too. It won't be too pretty, and will make incrementally harder to remove & refit if necessary, but that will be a pain already a bit more sika or no.

Keep you posted with progress!!

All the best
YoungDave

 

[Terry]

Hi YD if / when you come to remove it, until a couple of years ago I would have said use a Sharpe paper scraper but now I use a buzz saw with a old blade sharpened on my belt sander takes about 20 seconds a side and no blisters

 

[Raul]

I bedded the maxx fan on CT1. Its been over a year and a frosty -15C winter, lots of storms, and lots of standing water. So far no problems. The water actually protects from UV and keeps the sealant pliable. CT1 is used on industrial roofing, aquariums and works under water. It bonds to almost anything, even lead, except bitumen. If it fails, I will be using puraflex 40. I have used it to bond And seal solar panels integrated on roofs as coverings, no fails so far.

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[Landy Andy]

I did put extra sealer round where the two parts join on mine when I installed it. It looked like it could be a water weak point to me, and a poor design, unlike the rest of it.