# Forum Home Renovation Waterproofing  Sealing nail heads

## johnstonfencing

Hello, 
Just a quick one, going to seal nail heads in bathroom with sikaflex. Is it necessary to seal all nailheads that will be tiled over? Or just under waterproofing? 
cheers

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## goldie1

just in the wet areas

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## wspivak

> Hello, 
> Just a quick one, going to seal nail heads in bathroom with sikaflex. Is it necessary to seal all nailheads that will be tiled over? Or just under waterproofing? 
> cheers

  It's a good idea to seal all nail heads wherever waterproofing membrane will be used.  I'd personally recommend using an MS Polymer based caulk such as Soudal T-Rex or Multibond MS35 as opposed to a solvent based polyurethane like Sikaflex.   
Hope that helps  Waterproofing products, Waterproofing supplies. The WaterStop Shop® - Waterproofing products & supplies

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## johnstonfencing

Thanks for the replies.
Wspivak why do you recommend that over sikaflex?

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## wspivak

> Thanks for the replies.
> Wspivak why do you recommend that over sikaflex?

  Solvent based polyurethanes such as Sikaflex contain Xylene and Isocyanates.  Besides being hazardous to your health in enclosed environments, they can also adversely affect water based membranes by preventing them from curing properly while the solvent based polyurethane is still curing.  So when using standard Sikaflex, I'd normally recommend waiting at least 24 hours prior to trying to waterproof on top of them as they take quite a long time to cure properly.  If you're using Sikaflex-11FC (or equivalent), you can cut that down, but it tends to be far more expensive. 
MS Polymer (or Hybrid Polymer) products do not contain either Isocyanates or Solvent, and thus, you avoid all the potential issues listed above.  They also dry much faster, allowing you to work on top of them within 20-30 minutes on average. 
Hope that answers your query?  Waterproofing products, Waterproofing supplies. The WaterStop Shop® - Waterproofing products & supplies

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## johnstonfencing

Cheers, that does answer my queries. I have a couple of tubes of sikaflex11fc already so I'll be using those this time around.

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