What sealant to use?

[Lee Schierer]

I need to seal some metal roof flashing that is inserted into a saw cut in concrete block wall where the roof meets the wall. What is the best sealant to use that is weather proof and that can survive long term exposure to the sun and elements. I need a sealant that will stick to the concrete block and to the metal.

[Raymond Fries]

Silicone should do it. I think it comes in at least 25 year life.

[Biff Johnson]

Negative on silicone...use urethane or elastomeric sealant.

[Mel Fulks]

I just did a similar job for myself and used clear silicone. A solar dealer we know has been using it for many years to seal around pipes going through roofs and has found it hold up well in sunlight. I don't know that it is THE BEST.

[Stephen Tashiro]

I just did a similar job for myself and used clear silicone.

Use a colored silicone if you're going to paint over it. Paint doesn't stick well to silicone, but that defect is less noticeable with a solid color silicone. Clear silicone collects dirt and eventually looks nasty.

[Mel Fulks]

Yeah,it can get dirty. But in the case of flashing ,it usually doesn't get painted. I've been told that both the silicone and acrylic caulks last longer in clear because there are no pigments 'watering it down'.

[phil harold]

NP-1
Is what you want

http://www.cadeco.com/productfiles/Sonneborn-NP1.pdf

[Bill Rogers]

As a roofing contractor, I can tell you that what we would use is NP-1 or another one part Urethane caulking.

[Mel Fulks]

I'm making a note about the np1. For what I did I'm sure the silicone will work fine as it is below grade in gravel .retaining wall has the thick rubber glued on water proofing and it was coming unstuck at top so I flashed over it before installing pavers.

[Andrew Fleck]

NP-1
Is what you want

http://www.cadeco.com/productfiles/Sonneborn-NP1.pdf

+1 I don't even mess with silicone outdoors anymore. That stuff works really well.

[Lee Schierer]

Where does one purchase NP-1? It looks like Lowes will order it by the case, but I won't need more than a tube or two.

[Mark Bolton]

+1 on np1 or as an alternative quad will do well for many many years and stretch like a rubber band for ever

[Bill ThompsonNM]

Np-1. Search Amazon

[Mark Bolton]

Lee, if you don't find it online you might call some concrete equipment suppliers or industrial supplier in your area. Our local fastenal was stocking it for a while if you have one near by itd be worth a call. If they don't have it I'm sure they'd point you in the right direction.

[phil harold]

I have seen it at home depot once
but I would be cautious of big box product and how long it has been on the shelf
I would find a construction supply

http://susis.com/products/ ???

[Lee Schierer]

Thanks everyone. I ended up doing the job today with some Loctite PL S30 which is a poylurethane sealant with similar characteristics to the NP-1. I only needed 3 tubes and LOWES would only order a case of 36. I needed to get the job done today as it is supposed to rain off and on all week. The bad news is I didn't find any obvious signs of where the water is getting in. Hopefully caulking all the seams in the affected area will cure the leak. I guess I'll know tomorrow.

[ed malcom]

I need to seal some metal roof flashing that is inserted into a saw cut in concrete block wall where the roof meets the wall. What is the best sealant to use that is weather proof and that can survive long term exposure to the sun and elements. I need a sealant that will stick to the concrete block and to the metal.
there is a product called LEXAN that will bond to anything including glass.If you open a tube plan on using it all as in a couple of days it will go bad. The only type i have seen is clear.