Replies

1. 
   Stephen Sheehy|Mar 31, 2016 07:02pm|#1

   We used Siga tape, not sealant, for our Intus UPVC windows.

2. 
   Kevin Freeman|Mar 31, 2016 07:15pm|#2

   this is an innie style deal, i broke a piece of coil stock 90 deg around the head and jambs, taped back over, but the sill back leg is inset from the front. there are multiple 'legs' or gaps on the bottom side of the frame... taping really doesnt work the way i have installed. the metal runs up to bottom the frame... was planning on running a solid bead between metal and frame to seal.

3. GBA Editor
   Martin Holladay|Apr 01, 2016 04:47am|#3

   Kevin,
   Your description is confusing. Are you using aluminum coil stock to form a site-built sill pan? If so, how are you making the corners waterproof? Perhaps a sketch would help us understand.

   In any case, the two best tapes for taping vinyl (so-called uPVC is the same thing as PVC -- otherwise known as vinyl) are Siga Wigluv and Zip System tape.

   Zip System tape may be a little better than Siga Wigluv; read my blog on the topic scheduled to be published today) for more info.

4. 
   Kevin Freeman|Apr 01, 2016 06:25am|#4

   Im really mostly just curious about negative chemical interaction with sealants used on upvc... would a urethane based sealant have any long term negative effects? silicone just doesn't seem tenacious enough. Does tremco have anything that would be okay for upvc?

5. GBA Editor
   Martin Holladay|Apr 01, 2016 06:36am|#5

   Kevin,
   You may want to read this article:"Making Sense of Caulks and Sealants."

   In that article, Brian Pontolilo wrote, "Modified-silicone polymers like DAP’s Side Winder and OSI’s Advantage are difficult to classify because they combine the chemistry and benefits of water-base, silicone, and polyurethane products into one sealant. Like latex and acrylic products, modified-silicone polymers are easy to gun. Like silicones, they can be applied in extreme temperatures and can withstand rain almost immediately. Like polyurethanes, they are incredibly durable and adhere well to almost all substrate material. They are flexible, paintable with water-base paints (use a latex primer before coating with oil-base paints), have a lower VOC content than solvent-base synthetic-rubber products, cure quickly, and don’t shrink. The combined weatherability, durability, and flexibility of these new hybrids may make them the best product for sealing around exterior penetrations like windows, doors, and vents. At this point, the only known downfalls of modified-silicone polymers are that they are expensive and new."

6. Expert Member
   Malcolm Taylor|Apr 01, 2016 03:35pm|#6

   Kevin,
   I'd use Big Stretch. It is paintable, very durable and has a quite remarkable elasticity.
   http://www.sashco.com/products/big-stretch/