Trim troubles (long)

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Old 05-19-11, 08:54 AM
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Trim troubles (long)

Hi All,
I have begun replacing the 1958 windows in my house with construction windows with a nailing fin. I bought some composite pvc sill nose to use under the new windows, but I couldn't figure out a good way to attach it; from what I understand that stuff is usually just nailed into the Blandex sheathing -- I have that fiberboard stuff. So instead of having a 1/16 nail hole to fill from a trim nail, I'll need a longer fastener of some kind which also means a larger diameter and hole. Not sure what to do there (screws or nails).

I'll need to run fastener in to the studs or try and squeeze it in between the nailing fin of the window and the edge of the siding (about 1/4"). I don't want to nail through the nailing-fin as I'm concerned it may crack the fin. I've thought about drilling clearance holes through the fin to accommodate a fastener but I'll need to check with the manufacturer on that one first (warranty reasons) and that sounds like a lot of special work for each window (I have about 25). Any good adhesives for attaching trim? Seems like there should be some good goop to use that you can just slather onto the back of the trim and let it setup over night. Maybe that PL stuff everyone talks about would be good enough?

The trim opening from window frame to top of siding is about 1-1/2". Regular 5/4 trim board won't work as a "sill" there because that stuff is only an actual 1" thick.

So, I ended up experimenting with a piece of old brick moulding. I ripped a 10 degree angle along the top face so the water could run off, and then cut a rabbet joint in the bottom to act as a "lip" over the edge of the siding. This way, I could run fasteners through the front of the "lip" and be far enough away from the nailing fin. It looks kinda like this imgur: the simple image sharer

Now, the thing is the side moulding needs to be about 1-3/4" wide, the top moulding about 1-7/8" wide and the bottom 2" wide (brick moulding). I stuck a couple pieces in to see how it would look and the 1/8" differences aren't noticeable from 20 feet away. The problem is, I don't want to use Brickmould for the trim. I just want to picture frame the windows with flat trim boards as it seems it would look much better on this style of house. I may need to use brick moulding for the bottom sills though because I'm having a tough time finding trim which is beefy enough for the design above. Anyone have any ideas?

So, then we come to the type of trim. I don't want to use pine here as this is the north side of the house. It never gets any direct sunlight. The windows I pulled out had been cobbled up with layers of foam over the years and the framing was completely trashed. The king studs had buckled in on the garage side because they were nearly rotted through (just bought the house last year). The point is, this side of the house has had historic dampness problems so I want to use either Azek or Cedar - they are about the same price as far as I can tell.

The Azek stuff will never rott, but man there sure are a lot of issues I've been reading about. Expensive LRV paint (if you can get it to stick), expansion/contraction, no color options other than white, glue joints coming apart, sanding, warping... it sounds like a real pain in the ass. Cedar, on the other hand, has none of that other than maybe some warpage (I've got 12' to cover). it's much more impervious to rott than pine, and it can be painted with regular old latex (but I did read somewhere it needs to be oil based.. not sure).

I have no experience with Azek or Cedar trim, so am I on the right track here at all? Anyone have experience to share?

Thanks!
 
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Old 05-19-11, 05:41 PM
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Depending on the angle of the sill nose and how tight it fits up to the bottom of your windows, you sometimes want to run it through the table saw to make a flat spot on top, so that it doesn't leave a wide gap between the window and the sill nose. I run a bead of sealant on top of it before setting it in place. Then predrill holes and use 3" long exterior trim screws to attach it. They will be long enough to reach the framing. PL Polyurethane is good, but don't count on it alone holding your trim.

Personally, I'd use Azek (or similar). It costs a fortune, and it is kind of a pain to use, but the benefits outweigh the drawbacks. With cedar you also have to sand any cuts you make- the difference being Azek should hold paint better than anything else. You could look into this stuff called TrimBonder, it's a 2 part epoxy that works nicely to seal Azek to Azek. So if you have any joints you are worried about coming apart, use it as the glue, and use it to "caulk" any bad looking joints. It sets in about 10 minutes so if you are going to stop and start alot, you need a boatload of nozzles. It also takes a special 2-part gun. You can also use it to fill nail holes (or cover heads of countersunk screws) and then sand it flush with an orbital sander and paint it.

Cedar is nice, but you'll have a very hard time finding anything that's clear. I usually buy cedar 2x6 and plane it down to 5/4, then try to cut around the knots. It's best if you prime all 6 sides of each piece after they have been cut to length, and if you have the time, paint all 6 sides too. Then install, then caulk and install a final coat. By the time you cut around knots you may wish you would have just used PVC.

Generally when you set windows in existing openings (as when replacing an existing window) it pays to center the window (side to side) based on the distance from the new window to the edges of the old siding, and then raise or lower the window so as to try and make the head trim width match the side trim width. Of course if the old window was way out of plumb/level/square you can't do that, or if you need to position the window so as to cover interior paint lines that may take priority. But a little careful measuring before you put all the nails in the nailing fins can sure save a lot of headaches later.

Being worried about fasteners penetrating the nailing fin made me laugh. But if you are worried about your window warranty you might also read their fine print about how far the trim is supposed to be positioned away from the edge of the window. Many mfg's will specify a 3/8" gap filled with backer rod and caulk to prevent any expansion of the siding and trim from affecting the window. I think that's a crummy requirement because it makes every window look like crap.
 
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Old 05-20-11, 05:18 AM
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I would add that if you use cedar - it's needs to have a good solid coat of oil base primer to seal in the tannins, latex is fine for the top coat.
 
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Old 05-20-11, 08:38 AM
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Thanks - So you have had pretty good luck with Azek holding paint? I was reading it can take up to a month to dry. Not too excited about having dust, leaves, bugs and bird crap drying into it, but maybe it skins over quick enough?

Anyone know if color choice has improved on the Azek in regards to low LRV paint? I was reading you have to pick colors with an LRV of 55 or higher. If you're kind of limited on color choices with Azek, my wife is sure to have something to say about that...On a weekly basis... until I take all the trim off. Anyone know of an online color wheel showing colors with LRV rating? Found this one, still googling.. Accessible colour schemes - 30 LRV rule


Yeah, the knots in the Cedar are a problem. I called around to some local lumberyards this week and not getting a clear picture of what each one considers as a tight-knot or premium grade. Some of them order it for you and you get what you get. I don't like that idea. I prefer to hand-pick the boards off the pile myself. I've heard about some putty or something you can use to "spackle" over the knots, anyone got a brand they like?

Yeah, I centered the windows the best I could and ended up within an 1/8". The previous owner hacked out a 1/2" from the top plate (with a claw hammer I think) so the framing was a mess. I can't imagine what professional contractors must run into on a daily basis. It's got to be a brain numbing experience.

As far as attaching the bottom trim, I could just cut the siding back 1/2" and end up with a 2" width, same as the top. This would eliminate any goofing around modifying the trim with a lip and give me an extra 1/2" for nailing clearance. I've just never been too steady following a chalk line with a skil saw. It's probably the best way to go though. Maybe I can screw a board onto the siding as a straight edge to follow.

Thanks again, great reply!

PS: just found an RGB to LRV chart here: Dulux RGB / LRV Table - NewTek Discussions
 
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Old 05-20-11, 11:26 AM
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marksr - thanks for the tip on the oil based primer. I was wondering about that.
 
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Old 05-20-11, 12:21 PM
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"I've heard about some putty or something you can use to "spackle" over the knots, anyone got a brand they like?"

I like to use caulking to fill the voids in knots on exterior siding. I prefer the 'white lightning' brand but the main thing is to use a siliconized acrylic latex caulk - it's paintable. You could also use painter's putty, window glazing or an exterior spackling. Occasionally bad knots need a pigmented shellac [zinsser's BIN] to seal them although generally a good heavy coat of oil primer is sufficient.
 
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Old 05-20-11, 05:25 PM
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I've never heard of any problems with paint drying on Azek. Don't think you ever want to use oil based on Azek, only 100% acrylic. I have used Sherwin Williams Vinylsafe paint and a little SoPro Duckback to match my cement siding colors. No problems. SW says they can mix me any color to use on Azek, so I dunno why you think u are limited to colors. IMO it's wise to stay away from dark colors no matter what. But they say the Vinylsafe works.


If you are using sill nose I'm not sure why you'd want to cut the siding back even more on the bottom, since sill nose is usually 1 1/8-1 1/4" thick.

My brain is permanently numb. Not sure if it's from being in the business or if its from the Bacardi 151.
 
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Old 05-23-11, 08:50 AM
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Thanks for the replies. I think I've been reading older info about the paint. After some digging around it looks like that Vinylsafe breed you mention is the stuff to use according to this Azek document: http://www.azek.com/pics/reference_d...t-Bulletin.pdf. Google is great but it's hard to weed out the outdated information sometimes :/

I ended up picking up some nice looking cedar 2x4 on Saturday. Ripped it down on sunday and primered it with some of that Zinnser oil-based stuff. I'm assuming that White Lightning is the stuff to use for caulking gap between siding and trim too, not just the trim joints?

Oh, the sill nose just was big enough, but I coulnd't figure out a good way to attach it without nailing through the nail fin on the windows. By the way, what made you laugh about that? I didn't quite catch your drift on that.

I may try the Azek on a couple of double hung in the back which are close to the ground (about 6 inches above from submerged laundry room). It will be shorter trim pieces and probably hold up better to the moisture.

Oh, as a general rule of thumb, is it better to have the sill and trim set back in from the front of the window frame? The front of the awning windows stick out about an inch from the front of the siding so if the goal is to let water drip off the window frame without hitting the sill, I can accomodate for that with my trim depth.
 
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Old 05-23-11, 04:28 PM
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It made me laugh because you *always* have to nail through the nailing fins when you put the exterior trim on.

If you are using sill nose, it will stick out about 1/2" farther than the head and side pieces do. I like it when the head and side pieces are about 1/4-1/2" past the front edge of the window. This gives me a nice inside corner to caulk around the entire perimeter of the window. If your trim isn't thick enough to give you an inside corner where it meets the window (depending on what you're using, 3/4" is too thin, and 5/4 is usually flush) you can usually back out the trim with some 1/2" exterior grade plywood as a furring strip.

I don't like the look when the window sticks out farther than the trim does. (as in your last question) But I've done windows for 20 yrs and I suppose you could say that I'm a window snob.
 
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Old 05-23-11, 04:36 PM
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"I'm assuming that White Lightning is the stuff to use for caulking gap between siding and trim too, not just the trim joints?"

Yes, I like to use white lightning for most of my caulking needs [there are times when specialty caulks should be used] While I referred to using white lightning to fill the voids at the knots, I also use it for caulking joints. White Lightning is an adhesive caulk but you should take that fact with a grain of salt, it can be used as an adhesive but if adhesion is the main purpose - there are better alternatives for that type of use.
 
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Old 05-25-11, 10:39 AM
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Interesting note about nailing through the fin when putting the trim on. That explains why I've had such a difficult time trying to figure out how to *avoid* putting nails through it. It's not the way it's normally done. Oh well, chalk another one up to inexperience I guess. So you've "shimmed" the trim out as well when it's been to thin? I was wondering about if anyone ever did that. One brief recommendation I got somewhere else was to use "fan-fold" insulation board. I also discovered backer-rod when googling the other day. With that info in hand, I can see why the 5/4 Azek may work just fine for what I'm doing.

Glad you are offering up that 20 years of experience since I've only got about 3 weeks, thanks!

Marksr: Thanks for the info on the caulk. I'll use that stuff on the knots and between the trim & windows. Luckily, only have one so far as I managed to pick out some pretty clear cedar and cut around the bad spots.
 
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