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How would you flash this?


Shivaya's Avatar
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07-13-15, 10:38 AM   #1  
How would you flash this?

I guess I did all this research on how to install a window, but now I'm at the flashing part and I realize I know NOTHING about this, so I would really appreciate it.

I think the logical order would be

-fix concrete on the top corners
-flash
-stucco around the rest to create an outwards slope/finish the concrete.
-Caulk

If this is correct, I guess I am just looking for tips on what type of pre-shaped aluminium to buy (if that even exists), and how I go about installing it.

I understand this is probably going to be an unpleasant thread to answer to because we are starting from scratch, but as usual, I am eternally grateful for your answers.

Thanks!
Nic

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07-13-15, 10:54 AM   #2  
IMO it was a mistake to put in a jamb that isn't exactly as wide as the concrete wall is. Also a mistake to not use the nailing fin which would have helped with the flashing. (thought we talked about that?) And I would have probably installed the window nail fin flush with the exterior of the wall, not inset, which would also help with flashing and would have eliminated any add'l concrete work.

But at this point, yeah I would say that you will be relying on caulk and sloped cement to do your flashing for you. I would probably staple some foam sill sealer onto the wood as a cushion, to act like an expansion joint since wood and concrete should not touch, and then use mortar mix to make a bevelled cap for the bottom and sides, following the outside edge of the window as a guide. Top could be trimmed with wood. Once the concrete has cured, use a good polyurethane expansion joint sealant to seal the window to the cement.

Once or twice I had to install a window in the manner you did and I made a PVC jamb (like Azek) and sill and face trim, test fit all the pieces one by one then assembled it, and sealed it to the window after it was installed. Not super secure, since you are attaching it to concrete with as few fasteners as possible, but it looked good.

 
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07-13-15, 12:21 PM   #3  
We did talk about the nailing fin, but there was an issue where I couldn't get the window I wanted until at least 2 weeks, so one morning I went to my local used material store, and it just so happened that I managed to pick up that window immediately and for 50$, so I decided to make it work. I also opted for a jamb which was the same width as the window, instead of the wall, which I am hearing was a mistake.

I didn't put it flush with the outside edge of the wall because all other windows on my house were installed like this one.

Long story short, mistakes were made, everything you just told me is noted and will be integrated into my learning experience for next time, but now this is what I have to work with.

You talk about caulk and sloped cement, but is that really enough? Shouldn't I use aluminium flashing as well around the window?

 
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07-13-15, 04:50 PM   #4  
Well there's more than one way to skin a cat. One way is not necessarily right or wrong.

Cement is permanent, so if you do a nice job with the cement, I would consider that "done". Aluminum is commonly used to cover ugly framing, so you "could" use it but I dunno why you would want to.

 
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07-13-15, 07:07 PM   #5  
Near imposable to seal what you have there the way you installed it.
Is that a replacement window?
If so I would have at least installed it so it set proud of the rough framing by at least 1" and used jamb extentions on the inside.
Wrapped the wood with window tape.
Trimmed it out with PVC lumber starting at the bottom with a piece cut at an angle at the bottom to match the slope of the concrete.
If that window does not stick out beyond the framing anything you try to add to the wood at the bottom is going to act like a funnel.

 
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07-14-15, 08:25 AM   #6  
True - thank alot Xsleeper. I'm just thinking that it would take alot of cement to build up around that frame, not to mention getting it to stick at the top and sides. I totally understand the flashing thing now. I would "covered" the overlapping wood with aluminium. Oops.


joecaption, I'm sorry but I have to disagree that it's near impossible. I understand I messed up and will have to do it in a non-traditional way, but I don't see how flashing (or cement) sloped away from the window and caulked properly would not be sealed.

 
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07-14-15, 10:09 AM   #7  
Well, you probably wouldn't use cement on top, unless there is already cement above the window. Can't recall where your other pics were in the last thread. You would definitely want a wheel barrow and would need to get the consistency of the mix just right, maybe sweetening it with a little extra portland and bonding agent.

 
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07-14-15, 11:13 AM   #8  
oh yeah that's true, I don't really have the need for cement on top.

That being said, let's say I try to do it entirely with cement, do you think I could use Quickrete like you suggested in my other thread about repairing that corner up there?

Also, would I basically build it up as close as possible to where the window starts, and then caulk between the cement and the window frame?

 
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07-14-15, 04:48 PM   #9  
No, the stuff I recommended for the patching is probably not what you want to use. You will be needing a big bag or maybe 2, depending on how thick you want it to be. You could also make a form for the front... tapcon it onto the perimeter... Use that form to pack your concrete so that you have a nice even bevelled perimeter and finish. Once you get the concrete floated and smoothed, you would remove the forms so as to gingerly smooth and top the outside edges. Or you can let it set up with the form on, and just plan on topping the face of it later.

 
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07-14-15, 06:48 PM   #10  
Got to be kidding me.
Concrete should never be in direct with untreated wood.
All those window bucks are already have to have issues because there in direct contact with the concrete.
No way is any form of caulking going to seal long term between vinyl and concrete.
Vinyl expands and contracts, concrete does not.
Calking never should be counted on as the main way to keep water out!!!.

 
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07-14-15, 07:17 PM   #11  
Joe. I suggested a foam sill sealer as a gasket between the concrete and the PT wood in post #2 along with the sloped, beveled, masonry cap. Also, caulk is used as the "primary" way to seal lots of windows installed in masonry applications. In fact, it is ALL they use commercially. As for the expansion differences, that is why a good polyurethane expansion joint sealant was recommended. A silicone like Dow 791 is probably what would be used commercially.

 
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07-17-15, 11:17 AM   #12  
OK, first and foremost, you can't really tell by the picture, but there is sill gasket around my buck between the wood and the concrete. I also used expanding foam where I could/needed to.

Second, I spoke to another more experienced man I know, and his suggestion was to add an extension to the wood that is there now (again, with sill gasket, perhaps a 2x3 or so), and the flash/caulk that. What do you guys think of his idea?

I don't like the idea of trying to rebuild the window frame with 3" of concrete all around. I'm not saying it's not doable, but I don't have alot of (any) experience working with concrete, so I think it would end up causing me more head

 
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