Bay Window cable ties


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Old 05-30-06, 08:11 AM
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Question Bay Window cable ties

I'm installing a Pella 30 degree bay window. I have a 36" overhang where it is being installed so the idea was to tie the bay right into the existing soffit. The problem is that Pella wants cross braces installed to support their cabling clamp, but there is no access to the rafter tails unless I tear apart the soffit as this is far beyond the birds mouth. This will create a huge mess as there is blown insulation in this area. What is the best method to cable these up utilizing an existing soffit?

Also, according to the instructions, there is going to be a small 1-2" gap between the soffit and the head of the bay window that I am supposed to block in to support a clad head trim. It seems this would let cold air infiltrate through the 3/4" head. Again, how is this "typically" handled?
 
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Old 05-30-06, 10:15 AM
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Blow in insulation is usually in the ceiling joists, not the soffit. Unless you "know" the soffit is full of cellulose, that's not an issue. Usually there is just a little bit of cellulose that blows through the rafter bays and it's not a big deal. At any rate, blocking MUST be installed between the rafters as the instructions say so that the cables can go straight up from the mullions to the blocking. There is no other way other than doing it right, which means cutting out the area of soffit that is directly above the window (but it will all be covered up once the window is installed, since the area you cut out is the exact size of the window, minus the wall thickness.) It's actually EASIER to remove all the old wood soffit around the window, install the window, have a lot of room to work over the top of the window, fill the top up with loose fiberglass insulation, then install blocking all the way around the perimeter of the bay and then cut the soffit to fit and put the soffit back up around the window.

Typically, I laminate foam insulation onto the window by glueing 1" Thermax onto the tops and bottoms of my bays before installing them. In my area, that provides enough insulation (plus what you insulate from the interior- around the jamb) and no one I've done one for has ever complained about a cold head and seat in their bay or bow.

To cover any gap around the top, I usually will screw a 1x2 or 2x2 around the window after it is installed, then wrap it with trim coil to match the color of the window.
 
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Old 05-30-06, 03:39 PM
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Thanks for the feedback XSleeper.

I want to be certain I understand correctly. You are suggesting cutting out the existing soffit, installing the window, applying insulation on top of the window in the soffit area (seat area as well), blocking up the 1-2" gap between the window and the soffit and then trimming it out with coil stock.

A couple of questions...How do I fasten the blocking between the soffit and the head once the window is in place? The head is only about 3/4" thick and seems inadequate as a nailing surface. Do I nail it to the rafter lookouts or do these need to be removed to accomodate insulation? Also, I'm wondering if adhering twolayers of owens corning pink insulation which I believe has an R-7 Rating (x2) would work. I'm in minnesota, one of the coldest states in the lower 50.
 
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Old 05-30-06, 04:31 PM
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Ok, here's what I do:

First, I lay the bay down and chalk a line on the top and bottom of the window that will represent the level of the sheathing once the window is installed. I measure the distance from the front of the window to that line and then rip the foamboard to width on the table saw. I temporarily tack a cleat onto the window at the chalkline so that I can set the foam onto the cleat and trace the shape of the window. Once it's cut out, I glue the foam onto the head and seat using PL300 foamboard adhesive, and tack it with cap nails, making sure they are the correct length so that they do not pierce the interior of the head or seat. (I drill a hole in the foam before installing it so that the cables and nuts are still accessable.)

I also make a template out of 1/2" OSB that is the same size as the foam, and represents the exact size of the window. I screw this to the soffit (centered on the rough opening) and use it as a guide to cut the soffit out, so that the soffit is cut out exactly above the window. Then I remove the template and save it for later. (it gets installed over the foam on bottom after the window is installed.)

Once the soffit is cut out, you would then need to remove the soffit around the window opening so that you have room to get in there later to attach the cables. (removing the fascia and gutter to get at the cables isn't usually an option.)

The cable CAN be attached right to the side of a rafter provided one is closeby, and does not make the cable angle more than 45 degrees. (usually you aren't lucky enough to have the rafters right above the cables, which is why blocking is suggested) If needed, blocking should be installed directly above the cable location, and should be securely attached to the rafters on both ends. I usually use a 2x4 or 2x6 oriented vertically, and attach the cables to its side.

Once the window and cables are installed, the cables get their final tightening from below. Ensure the bay is level plumb and square before tighting the cables. A gap on the side casements or doublehungs can sometimes be adjusted first, by adjusting the entire unit side to side (for square) or if the window is square, second, by tightening or loosening the cable nuts below, which is actually raising the mullion, in relation to the sides of the bay. The cables should just be snug, and should have equal tension. I twang them like a guitar string to compare them.

Since the soffit is removed around the window, I install blocking around the outside of the window after the window is installed, fastening it between the existing soffit framing so that there is solid blocking around the entire perimeter of the window. I stuff added fiberglass on top of the window, since heat rises. If you use 2 layers of R-7 foam, that should be great. Then I reinstall the pieces of soffit that I removed earlier, since they are already cut to fit against the window. Then the 2x2 I referred to before can be screwed up into the soffit blocking, and gets wrapped.

I'll install the 1/2" OSB piece onto the bottom and cover it with aluminum coil or aluminum soffit. Then cap the front edge of everything as needed with trim coil.

I'm not sure if this answers your questions or not... if not, just ask, I'm glad to help.
 
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Old 05-30-06, 08:39 PM
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Thumbs up

You are a lifesaver XSleeper. All of the information you provided will be put to good use. The soffit template detail was extremely useful.

There are a couple more things I would like to clear up.

First, I am planning to frame in below the window approx 18" or so to follow the 3 sided contour of the window, sheath and side it. The instructions recommend using a Knee brace if the window is to support any weight and it is my understanding that the cables are only to support the weight of the window, no additional weight. Since I plan to finish below the window as well, I would rather play it safe and make sure the window stays put should the cables stretch and/or have a guest inadvertantly sit on the window seat. Any thoughts on knee bracing and contour framing below the window?

Second, if I do get lucky and a rafter is within the 45 degree angle for the cable on only one side for example, do I only install one cross brace for the opposite cable clamp or still install two cross braces directly above the mullion?

Finally, I selected 1" owens corning pink foamboard to make sure I have adequate clearance with the soffit with a r-5 (PL300) and will top the head, seat and additional "space" beneath the seat with R-25 batt insulation...this is Minnesota and as you can see, I would rather overbuild than underbuild.

Thanks for your patience...I only want to do this one once.
 
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Old 05-31-06, 10:26 AM
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You could put in one cross brace if only one is needed. Connecting to the rafter will actually be a stronger connection than attaching to blocking.

And regarding the box you will be building underneath, you would obviously wait to build it until after the window is installed. I never build anything underneath, but if I did, I'd open up the wall straight back from the mullions, and make sure there is some blocking between the studs there. Then replace that sheathing, and frame the middle section first, making it appear like a "box" below the center section of the bay.

Don't be afraid to screw to the bottom of the window to connect everything together. Sheath the SIDES (perpendicular to the house- not at an angle) and front of this box and shear nail it so that the box stays "square". It won't be able to sag if you put sheathing on the sides and there is blocking behind it. Sheathing the sides of the box would be the equivelent of kneebracing. So you really don't have to worry about the cables holding the weight of anything you build below. The box will be self supporting if you build it as described above. Screwing it to the base of the bay window will only serve to tie the two together as a unit. Once you have the center "box" built then it would be easy to frame up the sides, and put sheathing on the angled sides. It might help if you framed this box with 2x2's, and screwed 2x2's to the bottom of the 1/2" OSB (the template I glue and screw over the foam). Hold the 2x2's back from the front edge so that the sheathing below will be at the level you want it to be. You "may" want to hold the sheathing back far enough that your siding will be flush, or even a bit behind the edge of the bay.
 
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Old 06-03-06, 05:53 AM
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Angry Big Problem

Thanks again XSleeper. When I was referring to extra weight, it was that of anything or anyone sitting on the seat. My understanding is that the cables are rated sufficient for the weight of the windows, but not any additional "seat" weight. If anything substantial or anyone is to sit on it, knee braces would be required?

I have a MUCH bigger issue right now. I removed the existing flush window to install the bay. I framed my R.O. to the "spec" size R.O. and the window seems fine on the head and seat, but something is not right on the width. On the exterior, there is about 3/4 - 1" opening from the jam to the framing on each side, but there is over 1-1/2"+ on each side from the jam to the opening. In addition, the jams are at an angle, so I'm at a loss at both what to do about the framing gap(s) and how to secure this thing to the side jams. Was I supposed to (re)frame this specifically for a bay window? It did not indicate any special 30 degree "angle" framing on my instructions? I'm at a reall loss here.
 
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Old 06-04-06, 11:55 AM
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As far as the added weight of someone occasionally sitting in the window for a few minutes, I wouldn't worry about that. Most of that weight would be on the exterior wall, not on the very outside edge of the window, where it would exert the most force. I've never had any problems with cabled bays or bows sagging.

You likely have the R.O. the right size. I just ensure the bottom is level, caulk the sill plate, set the window in, shim the top straight, use finish screws along the top and bottom, and secure the sides to the sheathing with the nailing fin, if so equipped.

As far as the sides, I'm guessing that you are having trouble picturing how the window is going to be trimmed on the interior? Here's a photo of one way to do it:

http://pg.photos.yahoo.com/ph/thexsl...nm=d55fre2.jpg

If you prefer, you can cut the ends off the head and seat, frame it in with 2x4's, add some drywall to each side, then you wouldn't have to use such wide trim.
 
 

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