Different Sealant for Different Surfaces?

[mailmanx]

I live in San Diego and will be replacing my old 1970's aluminum frame single-pane windows with Milgard Tuscany retrofit windows. Most of my windows are west facing and get very strong afternoon sun. The siding is wood.

I intend to use a very good quality sealant, whether a neutral-curing, low modulus silicone or a terpolymer such as Novaflex. My question is whether it would be a good idea to use one type of sealant for the vinyl-to-aluminum seal and another for the final bead between the vinly and wood?

I've attached a photo of one of my windows with the old wood trim removed.

Thanks!
Michael

P.S. - How many 10-oz tubes of sealant, total, do you think I will need per window?

[Windows on Washington]

Whatever you decide on should have similar adhesion characteristics and I would use the same sealant for both.

I would imagine that is your properly back any larger voids with backer rod or foam that one (1) tube per window should be sufficient.

[mailmanx]

Good point about the similar adhesion characteristics. I'll consider that.

I definitely plan to use a backer rod before putting on the perimeter bead. The Tuscany windows have a pretty wide flange.

A lot of people seem to recommend OSI Quad. I can't find the original anymore. Does anyone have input on whether the new, low VOC Quad is still good stuff?

[Windows on Washington]

You won't find the older stuff any longer and you wouldn't want to use it. It does cure up in the tube if it is old enough.

If you need a paint-ability, look at the proper color Quad or if you do not, look at Silicons.

[mailmanx]

Thanks for the input on Quad. I don't need paintability. I'm just planning to match the white of the new vinyl flanges.

I will shop around for the best price I can find on a neutral curing, low modulus silicone. I've already mentioned Novaflex. Another that interests me is one of the Dow Corning 79X series (791, 795, 797).

Trying to find these sealants can be a bit of a challenge for a DIY guy, but I think between the intenet and local window dealers, I will find what I need. I'm open to suggestions for known sources of good silicone that are either local to San Diego or are willing to ship it to me.

[Windows on Washington]

Many of the building supply houses or a roofing supplier have better sealant availability.

[TheWindowNerd]

The local alside store sells Nova Guard silicone packed for Alside.
Nice stuff for $4+ a tube.