# window trim question



## blackestate (Sep 4, 2011)

So I installed a new pella vinyl window. Used the "rubber" seal tape, around the window, As instructed. 

So now I come to placing the trim around the window. I have 5/4 pre primed trim. And understand the configuration so the rain has somewhere to go. 

I placed the trim right next to the window. But the instructions say to have a 3/8 backer rod inserted to create a 1/2" gap. to give the sealant shape and depth.

So where do I find this rod? and do I remove the trim and place it with the rod and gap. Then caulk the trim to the window?

Also, What do I use to shim the trim so it is level. It angles away from the window due to the nailing strip, I used Cedar shims, but feel like that was not a good idea. 
I should get this right before I move onto the next. 
There is no siding on the wall right now, just the sheathing. Will be installing the hardi plank in a week or so.

thanks


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## Just Bill (Dec 21, 2008)

I am assuming a new construction type window with nailing flange, and you are doing the exterior trim??? Everything goes over the housewrap. You should have housewrap and flashing on the sill framing, there can never be too much waterproofing. You should have run a bead of caulk under the flange before installing the window, then the self adhesive tape starting at the bottom, then the sides ovelapping the bottom, then the top overlapping the sides. This all should have gone over your housewrap, be it tyvek or felt. You will still need a metal flashing at the top that goes up under the housewrap and over the window edge. Install trim, caulking the trim/window edge.


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## Windows on Wash (Aug 30, 2011)

+2

Backer rod and caulk is typically for an insert/retrofit window sealing.

Sounds like you have a new construction (nailing flange) type window.

Bill is right on about the rest of the flashing etc.


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## HomeSealed (Jan 3, 2008)

Just Bill said:


> I am assuming a new construction type window with nailing flange, and you are doing the exterior trim??? Everything goes over the housewrap. You should have housewrap and flashing on the sill framing, there can never be too much waterproofing. You should have run a bead of caulk under the flange before installing the window, then the self adhesive tape starting at the bottom, then the sides ovelapping the bottom, then the top overlapping the sides. This all should have gone over your housewrap, be it tyvek or felt. You will still need a metal flashing at the top that goes up under the housewrap and over the window edge. Install trim, caulking the trim/window edge.


All good advice except the wrb (housewrap) should go _over_ the tape on the top and sides. Wrapping the housewrap into the hole is an outdated method.


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## Clutchcargo (Mar 31, 2007)

Backer rod can be found in any big box store around in the section where they have door sweeps.
I'm installing Andersen windows. The instructions say to leave 1/4" between the window and trim. Push in backer rod around the window and then caulk. I didn't. That large of a gap looks like crap. I left 1/8" around the window with no backer rod.
I'm using Azek trim boards and Azek historic sill. 
I assemble the window trim first using pocket screws and bring the entire assembled trim box up to the window. I space it evenly around the window by using nails as spacers and screw the entire thing into place as one unit.
I did the same with a door but I did have to add some shims around it because the wall was far out of wack.


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## blackestate (Sep 4, 2011)

Yes a winow with a nail flange is being used.

I should have asked here first I guess. Thought I had found solid info.. 

So I installed the self adhesive tape in the window sill framing and up the sides about 6", (it has a silver aluminum type cover on one side) and wraped down onto the house wrap. I then installed the window, without calking. And nailed the flange in. Then I taped up the sides on top of the house wrap, then across the top overlapping the sides and the top was under the house wrap. Then I pulled the house wrap over the tape at the top and secured it with some duct tape. thought that was good for the install. Is it ok, or do I need to start all over? 

Then I placed the trim boards around the window using the same configuration as the tape, except at the bottom I ran the trim between the other 2 boards. 
Due to the nail flange and the tape the trim does not sit flat against the wall. So I spaced it out with some cedar shims. 
I also left only a tiny gap between the window and the trim. Then I was going to put a metal rain cap over the top trim board, and not the window. 
Then put the siding on and caulk it to the trim. This way I could remove the window and not ruin the siding if that need arise in the future.
Now I think I need a bigger cauling area.. Do I need to just seal the window to the trim at the outside, or does the calk have to go all of the way back to the base of the trim/window joint.
I though I had better ask and make sure it is all ok, before I go any further this weekend. 


thank you for the help.
Doug


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## chrisBC (Dec 28, 2010)

You need to make sure you don't have any "negative laps" in that with your housewrap and peel and stick, the laps will always be so that the water will drip down with nothing lapped in a manner so that water can ingress.IE start at the bottom and work your way up, always lapping over the bottom layer. When I was installing windows we would\

Tyvec: Wrap sill, sides, then top, all wrapped into opening, caulked onto RO framing to seal the envelope (standard around here anyways, may change regionally)

Then membrane (peel and stick) goes onto sill, wraps up onto framing (not the side paper). gussets as necessary. Side paper is placed over peel and stick (would usually tack it up and out of the way while putting on the peel n stick). Shims placed on sill for level, bead of caulk place on sill prior to installation. There are a few different methods depending on area and whether you are retrofitting and keeping siding in place, or applying housewrap over the whole wall. Whatever additional peel and stick/membrane applications you do once window is in (sides, top, etc.) just remember to always lap the materials properly, think of where the rain will go.

Duct tape has no place for a window installation, "tuck tape" (red) is fairly standard. 

For your trim I am trying to picture what you are doing, a pic would help. There are some great guides on the net for trimming out a window.

Remember not to nail the nails too tight to the flange with vinyl windows, for expansion and contraction. Same practice as vinyl siding.


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## loneframer (Mar 27, 2009)

To answer your question about the issue with the nailing flange, I always relieve the back of the trim on the table saw to give clearance for the flange and prevent it from tipping the trim out.

As for the clearances for backer rod and caulk, I think 3/8 looks hideous. That being said, you should adhere to that practice if you're going to caulk the juncture between the window and trim. 1/4" is the minimim, in my opinion.

If a caulk bead is too thin or narrow, it will fail over time. The backer rod helps to shape the bead and reduce the amount of caulk required to fill the void. The backer rod should be set back deep enough to allow for a decent thickness, or again, the bead will fail over time.

If you are not familiar with backer rod, it is simply a round foam product, available in different diameters.


http://images.search.yahoo.com/search/images?_adv_prop=image&fr=ytff-&va=backer+rod


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## blackestate (Sep 4, 2011)

I never thought about cutting the trim board enough to alow the nailing flange space. Thanks. 
Also I will get some backer rod, and caulk the window to the trim. if 3/8 looks that bad, what should I use? 1/4?
I will see if I can get some photo's, and get it posted. 

thanks


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## Gary in WA (Mar 11, 2009)

HomeSealed, do have a reference site of this you could share? "All good advice except the wrb (housewrap) should go _over_ the tape on the top and sides. Wrapping the housewrap into the hole is an outdated method."
Thanks, Gary


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## Tom Struble (Dec 29, 2008)

there should be no need to caulk the trim to the window:no:i gap it 3/16- 1/4'' and call it good,if your weather proofing depends on caulk you did it wrong


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## Tom Struble (Dec 29, 2008)

i also think the window flange should be direct to the sheathing on the sides and top,i see no advantage to pulling in the wrb into the ro,but i do see potential problems ,i prefer the B method


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## kwikfishron (Mar 11, 2010)

Tom Struble said:


> there should be no need to caulk the trim to the window:no:i gap it 3/16- 1/4'' and call it good,if your weather proofing depends on caulk you did it wrong


What happened to always follow the manufactures instructions Tom?
Blind caulk for me.






Tom Struble said:


> i also think the window flange should be direct to the sheathing on the sides and top,i see no advantage to pulling in the wrb into the ro,*but i do see potential problems *,i prefer the B method


Me too.


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## HomeSealed (Jan 3, 2008)

GBR in WA said:


> HomeSealed, do have a reference site of this you could share? "All good advice except the wrb (housewrap) should go _over_ the tape on the top and sides. Wrapping the housewrap into the hole is an outdated method."
> Thanks, Gary


I do not have a site handy, but that is how both Installation Masters and AWDI are now teaching it if my memory serves correct. It is also how OSI mandates its Winteq system be applied to offer their installation warranty coverage. 
It makes the most sense if you think about it. I don't understand why it would have ever been anything different.


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## HomeSealed (Jan 3, 2008)

Hey Gary, here is that link: http://www.buildingscience.com/documents/guides-and-manuals/gm-residential-water-management-details/
Note: _"Often, due to the different trades on the site, or the sequencing of materials being delivered to
the site, the windows may be installed before or after the installation of the drainage plane
material. In either case, provisions must be made to allow the window to be integrated into the
drainage plane of the assembly. It is important to ensure that the building paper or housewrap
laps over the flange and self adhered membrane at the head of the window. If the building
paper/housewrap is installed prior to the window, then a flap of paper at the head should be
turned up during the installation of the window, then the flap can be dropped back down over the
top of the flange. Using self adhered membrane flashings and other tapes to seal the nailing
flange at the head of the window, while reducing the risk of water intrusion, still create a reverse
lap and must remain completely sealed for the service life of the installation in order to be
effective."_

Don't you have that whole site memorized by now, :laughing:.


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## HomeSealed (Jan 3, 2008)

... if you are referring to the sides, I think that is less critical and I've seen it done either way. My problem is with the old method of wrapping the wrb into the RO on all four sides(particularly the top), and then sealing the flange to that. I still see this being done, and I can probably scrounge up some pics of what the consequences are as we repair 5-10 yr old homes with leaking issues on a regular basis.


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## blackestate (Sep 4, 2011)

Thanks so muck for the help. 
I do not have a digital camera, only a old school one. just like no cell phone. Guess I am a dinosaur. 
I will caulk it at about 1/4 gap, so it looks nice, and I believe I have done everything else that you have said to do.


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## Tom Struble (Dec 29, 2008)

kwikfishron said:


> What happened to always follow the manufactures instructions Tom?
> Blind caulk for me.
> 
> 
> ...


usually the trim and the window frame ''flush out'' and i can't get a good bead like that,like i said my water proofing is independent of any trim detail so i consider caulking my option

i usually find damp joints that have been back caulked it's not a technique i believe in

what needs to be sealed and is often over looked is where the flange locks in to the window on tap in units,some guys will roll the flashing tape over the joint but here i use silicone which is compatible with vinyl and the tape i use


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## tinner666 (Mar 14, 2005)

I've tried to put it all, including the flashing details in laymen terms here. http://www.albertsroofing.com/Window%20Flashing.htm


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## Decoramould (Nov 16, 2009)

HomeSealed said:


> Hey Gary, here is that link: http://www.buildingscience.com/documents/guides-and-manuals/gm-residential-water-management-details/
> 
> Don't you have that whole site memorized by now, :laughing:.


Had never thought of that - thanks for the link!


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## Gary in WA (Mar 11, 2009)

Oh..... I was ready for some brand new involved test results that I may have not seen. lol. I can't hardly remember important dates let alone memorize anything....(my secondary reason for always a link involved after my answers).

Testing done on leaking window/HW; http://dspace.mit.edu/bitstream/handle/1721.1/27029/56772711.pdf?sequence=1

pp. 56- folds of HW from installation dictate water paths when introduced under the HW

pp.57- installing the window flashing after HW serves no purpose as flashing

pp. 65- modified fold -on/under- at window flange/flashing

pp. 69- new "W-flashing" anyone seen this around? Yet? Ever?

pp.91- read the conclusions......

pp. 94- Method A,B, A1, B1- followed by HW, sealants, caulk, felt and flashing. A good read..... bring a lunch. (lousy pics).

PS. Tinner, why is there tape on the bottom flange of your window to trap water..... (don't shoot the messenger).

Gary


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## tinner666 (Mar 14, 2005)

GBR in WA said:


> PS. Tinner, why is there tape on the bottom flange of your window to trap water..... (don't shoot the messenger).
> 
> Gary


That was stuck there because some BI was insisting tape goes on the bottom flange. Metal counter flashing goes on the sides and covers it. THe metal extends just about 1/2" past that lower corner and the tape stays dry. It's just there for air intrusion, and an example pof what the BI wants to see before he'll pass it. Tape on OK, tape off, No Pass. 
Though it wasn't added in the example, I like putting ina sill pan, and it empties onto the lower flashing which runs across the bottom of the window and exits onto the outside of the siding.


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## tinner666 (Mar 14, 2005)

"what needs to be sealed and is often over looked is where the flange locks in to the window on tap in units,some guys will roll the flashing tape over the joint but here i use silicone which is compatible with vinyl and the tape i use"

I'll put a dab of sealant there too, then flash. There,my second piece of metal, the counter-flashing closes that off, and my drip cap passes over that. I put a dab of caulk where the metal meets.


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