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Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Sun Jul 25, 2010 1:25 am
by dinotoad
I have a porch roof of coragated metal and my mobile has a metal roof (standing seam?). The porch roof underhangs slightly from the mobile. It is leaking big time at the seam between the porch and mobile and also some from the seams in the coragated metal. I suspect it was made worse when the mobile was releveled.

What is the best way to reseal this joint and also the corragated metal seams?

My plan is to use Henry 209 from Home depot. It seems to claim that is would be the best to use in dry conditions. Any opinions?

I want to use something from Home Depot because I have limited options here and don't want to have to order something.

Thanks for all opinions and help!

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Sun Jul 25, 2010 11:53 pm
by JD
I am not getting a clear picture of the transition from roof to corrugated porch. Are the corrugated panels above the edge of the roof? If so, that may be a chronic problem. If it were me, I would find a way to cut the awning posts down to lower the corrugated below the roof line.

If the corrugated is below the roof line, it should have metal flashing going from just below the drip rail on the edge of the roof to the top of the corrugated panels. The flashing can be sealed with caulking. I would use something in a polyurethane made for roofs, usually called lap sealant.

Basically, none of the black asphalt type sealants should go on a metal roof. It will not last long and it is very difficult to get off. Most other types of sealants will not work well with the black asphalt sealants as it will bleed through and deteriorate white sealants. There is black butyl rubber lap sealants that will work pretty well but I still prefer the polyurethane.

If you could post a picture I could probably give more specific advice on sealing it.

I hope this helps,
JD

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Mon Jul 26, 2010 1:06 am
by dinotoad
The corrugated roof sits just below the mobile roof. There is no flashing, but the mobile roof does hang over the corrugated roof by several inches.

Thanks on the tip about black asphalt sealants! Henry 209 is a black asphalt sealant and it seems to be what Henry says is best. I will look for the polyurethane. Can you reccomend any specific name? I was worried about using the asphalt but it did seem like an easy way to go. I was going to use a couple of gallons because this seam is about 40 feet. The old roof has been sealed with more than one type of sealant including some silicone seal (I am not the original owner). Also some nails that go thru the mobile roof into the porch roof lumber have popped and are leaking. If I have to remove the old sealant, this is going to be a huge job.

What do you think about the white acrylic elastomeric selants like Henry 289? At least I can get them in gallons.

I will try to post some picture tommorow.

Thanks again, I will hold off until I get this figured out...

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Mon Jul 26, 2010 12:29 pm
by JD
The white elastomerics will work provided there is no standing water, basically meaning that all water will evaporate within 2 hours in moderate temps.

On awnings, I usually use metal flashing and tube sealants. I actually use Vulkem 116 which is not available at home stores. Stores that cater to concrete and masonry contractors will usually have Vulkem. At the home stores, DAP seems to be the main brand. DAP Premium Polyurethane Roof & Flashing Sealant is good stuff even though it is a black sealant. Their Sidewinder window and door sealant is OK, but not the best. The PL brand sealant, (PL Polyurethane Roof & Flashing Sealant) is sold at my local Lowe's and that would be my first choice at a home store. In the home stores this sealant is sometimes located in the roofing products area and not in the sealant area. Again, this is a tube sealant and not stuff in a can or bucket. I used the tube sealant over the edges of the flashing and screws.

Yes, pictures would help a lot. Like the "nails" you say are poking up. You may want to replace them with screws. But without a picture, I am not sure what you are looking at.

JD

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Mon Jul 26, 2010 2:18 pm
by dinotoad
Here are the pictures:

http://www.flickr.com/photos/11822199@N ... 463309861/

Let me know if you can/can't see them.

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Mon Jul 26, 2010 7:11 pm
by JD
Yes, the pictures come up fine. It would be better if the porch roof was 2-3 inches lower, but that may be out of the question. The continuous crack in the sealant that you see in the picture below really needs to be taped. Elastomeric painted over this crack may last a year or so before it cracks again. This is fixed by using seam tape over that crack/transition area. The roof seam tape they sell at the home stores is too stiff to work on this combination of corrugations and flat main coach roof. I would recommend using a spun fabric tape rather than a woven fabric or that screen type tape. I would recommend using Eternabond Web Seal [ http://www.eternabond.com/WebSeal-p/cr-wb.htm ] in a 6" width. 4" might work too, but you will need to get it pressed in to all voids real well. 4" might want to lift off of the corrugated because there won't be enough of the tape on the corrugated panel. The 6" x 50' roll is about $100. The 4" is about $65

The way the stuff would be applied is the entire edge is cleaned thoroughly. Remove any loose or peeling old sealants. Do your final last pass of cleaning with lacquer thinner. Be careful, very flammable stuff. This will make the old sealant area very tacky and help the seam tape to stick better. The seam tape as I mentioned is a spun fabric, which makes it able to stretch in any direction and is pliable enough to form fit into the two different metal patterns. This seam tape is waterproof in itself, but not UV resistant. The fabric is there to accept the elastomeric coating of your choice. The better the coating, the longer it lasts. The Henry's Elastomeric is only OK, not great. I think Home Depot sells Kool Seal, at least they used to. This may be a better product. I use Ames Research Maximum Stretch [ http://www.amesresearch.com/roof_coatings.htm#mx ] This product is generally an ordered product, but it available at some retail outlets. Check with Ames to see if there is a store near you.

Which ever product you use will work fine with the seam tape. The seam tape will bridge that crack area and keep the new sealant from cracking prematurely. I would put on at least 3 coats of sealant over the tape and about an inch past the tape on each side. You don't want to do "light" coats, but you don't want the product to puddle either.

If you wanted to do the best job possible, you could add an additional step between the cleaning and installing of the peel n stick tape. Ames research makes a trowelable caulk that you can apply with a putty knife. you could use this product to fill in the edge of the corrugated metal with a tapered slope rather than an abrupt and uneven edge. This would allow the seam tape and coatings to install better and last longer.

Hope this helps.
JD

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Wed Aug 11, 2010 4:29 am
by homebuff
Same problem here with my frt. porch deck "dinotoad". I was recommended to install the deck level with the roof line but instead I attached the deck a slight bit lower than it should have been.
About an inch or two. Mine looks a mess now with all tha black roofing tar cement & silocone mixed.
The tape & sealant looks like a better solution to seal mine. The biggest project is getting all that other gunk removed & cleaned off for the new apply. It had to be leaking right over my entry way into the house over the door.
Have to deal with the wafey steel roof panels that cover the deck though.
Attached the 16 ft lenth 2x6 board just below the top edge of the lip of the trlr. where the gutter once was.
Big Mistake there!!

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Sat Aug 14, 2010 2:46 am
by dinotoad
A question for JD:

I don't understand how to apply the Eternabond tape due to the standing seams on the mobile roof:
http://www.flickr.com/photos/11822199@N ... 463309861/

Also I wonder if it might be simpler to just use an white elastomeric roof cement and then an elastomeric coating. This porch roof is over a deck and it also leaks at the corragated steel seams. It would be nice to be able to be out there in the rain and I'm sure that the rain will begin to rot the deck but many of these deck don't have any roof over them anyway.

If I go with the White elastomeric roof cement, should I try to seal the seams first with the polyurethane chalk?

I did replace the popped nails with screws and rubber washers and this help a little bit.

Thanks for all you help!

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Sat Aug 14, 2010 7:49 am
by homebuff
The seam tape is a slow process having to roll it over all those high ridges but that's the way it has to be done if you want it not to leak then apply the cement over it.
My metal roof has the same product design on it. "Rolled corregated" roof design.
That's what I intend to do with my porch as soon as this hot 100+ degree temps cools down here in Okla. Heat index has been over 100 dgress for the past 3 weeks now & hope it turns out cool real soon. I can't take much more of this intense heat.
Hope you get your's sealed good.
David

Re: Sealing Metal Porch Roof to Mobile Metal Roof

Posted: Sat Aug 14, 2010 3:54 pm
by JD
You would just run the tape 50/50 over the seam and cut a slit in the tape when you get to a standing seam and just fit the tape around it. If the build up of sealants protrudes upwards where it is cracked, I would whittle that down with a utility knife before applying the tape. You want that spot to be as smooth of a transition as possible.

The "right" way to seal this area is to remove the old sealants, which would correct a lot of the problems and make the repair last longer. But I know a lot of people just won't go through that much trouble. So whittling down and taping is the next best bet. The tape will bridge these gaps and spread out the elongation over a larger area. This keeps the new elastomric from tearing at the old crack. To make the repair even better, you can fill that abrupt edge at the corrugated to standing seam panel transition, as shown in the image below.

JD