Sealant for roof fitting

Discussion in 'Self-Build Motorhomes' started by pelican, Jun 25, 2018.

  1. pelican

    pelican Funster

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    Please could you advise what is the best sealant for rebedding the roof vent on a gel coated fibreglass roof(Autotrail)
    thankyou
     
  2. Terry

    Terry Funster Life Member

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    Puraflex 40 (y) from Toolstation
    Terry
     
  3. andy63

    andy63 Funster

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    Depends on what you want...
    If its to be a permanent bond then the pu range of adhesives is ok..
    I tend to go with the non setting mastics for sealing the roof lights and the likes...
    Something like hodgsons seam sealant..
    Andy.
    ButyleneSealantSeamsealCVIDL99White-228x228.jpg
     
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  4. tonka

    tonka Funster Life Member

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  5. tonyidle

    tonyidle Funster

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    .......... or if you want easy to use as well as effective try W4 strip butyl mastic.
     
  6. mfw

    mfw Funster

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    Choices mastic tape or mastic gun you have decide tape is easier and cleaner uniform fit tubed mastic really has to be compressed to fill gaps and more importantly cleaning surface prior to doing anything IPA cleaner is good
     
  7. PhilandMena

    PhilandMena Funster

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  8. scotjimland

    scotjimland Funster Life Member

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    Any Non setting mastic.. tube or roll

    .. Carafax IDL 99 or W4 mastic on a roll

    Non setting mastic allows the window to get a good seal and allows for the differential expansion of the window frame and the roof on hot days without breaking the seal. .
     
  9. tonyidle

    tonyidle Funster

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    ........ and enables removal if it needs to be replaced in future.
     
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  10. scotjimland

    scotjimland Funster Life Member

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    indeed..
     
  11. CazPaul

    CazPaul Funster

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    Yes and me for this, good stuff and non setting as you say.
     
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  12. pelican

    pelican Funster

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    Thank you everyone for your answers.
    Guess I will go for the Sikaflex 221 as it is available locally, I did consider the Puraflex which seems less expensive but just wondering if its the the old addage "You get what you pay for"
    Thanks again
     
  13. andy63

    andy63 Funster

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    I dont think thats the issue with the pu adhesives...
    Ive used several brands over the years and they all do the job..
    I started off with sikaflex with the same train of thought but the price persuaded me to try other brands... as i said they all seem just as capable..
    Your decision has to be do you want the bond to be permanent or non setting so that the skylight can be removed without possible damage should it be necessary...
    Andy.
     
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  14. mfw

    mfw Funster

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    Ensure you use a good surface cleaner whatever you use will only work if the preparation cleaning is done properly
     
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  15. scotjimland

    scotjimland Funster Life Member

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    yet you have chosen to ignore the advice about using a non setting mastic and decided to bond the window to the roof..

    it's Not about cost, or getting what you pay for, it's about using the correct mastic for the job..

    if you ever have to remove it you will wish you had regarded the advice..

    if you prefer, there are several vids on youtube , none use a PU adhesive ..

    Dave Newell .. well respected member of fun with his own motorhome workshop LVS services

     
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  16. iandsm

    iandsm Funster

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    I don’t think it’s a matter of ignoring advice, given the answers available it’s just personal choice. I used Sikafkex 512 for my rooflight ( not window) with excellent results, it is flexible and will not shrink and made for the purpose the seal will not be affected by different temperatures and expansion/ contraction. Yes,it’s true it might be difficult to remove but no more so than sticky mastic. If ever the rooflight needs removal it will be past repair anyway and Sikafkex or any similar product is easily cut through with a sharp blade without damaging the roof. What is “correct” is a matter of opinion.
     
    Last edited: Jun 26, 2018
  17. tonyidle

    tonyidle Funster

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    Assuming you mean Sikaflex PU adhesive it isn't. It really isn't :D.
     
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  18. iandsm

    iandsm Funster

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    Sikaflex 512 Caravan Adhesive & Sealant for Caravans, Motor Homes & Trailers
    Its just matter of opinion. I used this on the second occasion I had to remove a roof light. I cut through the joint with a craft knife, removed the roof light then took off the remaining Sikaflex by some sanding but mostly with a chisel, it came off without much difficulty. Of course refitting the same roof light may have been more difficult as removal if the Skaflex from the groove would not be so easy but that was not my intention. However removal of a damaged roof light and fitting a new one was not a problem and I would use Sikaflex 512 again.

    I did quite a lot of thinking and research about this beforeI decided to use Sikaflex and from its great product and I am satisfied that the joint/seal is as good as new two years, and some very hot/cold weather later.

    What works for one person may not for another. As I have said was one person thinks is correct may not be the same as what another thinks and in the end its personal choice.
     
  19. tonyidle

    tonyidle Funster

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    I agree about it being a personal choice. However the Sikaflex product you describe is a superb adhesive and can only be removed by mechanical means (no solvent works) with the attendant risk of damage to the two components involved. You are correct in that it is possible to remove it without damage if great care is taken. On the other hand a butyl mastic, in whatever form, is very easy to remove and the remnants are soluble in White Spirit. Butyl mastic is non-setting and apart from the inclusion of dirt around the edges could be re-used (in terms of it's ability to seal) after many years in place. The strip form is exceptionally clean and easy to use and is as good at sealing as PU adhesive.
     
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  20. iandsm

    iandsm Funster

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    Yes I know it's a superb flexible adhesive and sealant and removal is by mechanical means, I am happy with that, and I know it can be removed without damage to the area if care is taken, I am happy with that. I appreciate what you say about mastic and that it's your choice is but my choice was Sikaflex 512 for my roof light. In the case of large side windows I would choose mastic, mainly because there's a possibility that the large window might need removal and replacement/reseal for one reason or another. Neither of us are wrong, we just have different preferences.
     

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