I’m in the process of restoring a badly butchered 120 year old Italainate home. In the 1970’s, the owners took out the original windows and replaced them with aluminum windows. Many of the rough openings were made smaller and the nearly seven foot windows were replaced with 5 foot windows.
We are now in the process of bringing back the original proportions and using wood windows (Marvin). On the outside of the windows, they will be trimmed per the original architectural details–so there will be no trim on the windows that we order. The original construction is a true 2X4, with 1 inch redwood sheathing, topped by 1 inch redwood siding. On the inside there is 1/2 inch sheetrock.
My questions are:
- Should I bring the jams flush with the siding and the sheet rock (i.e. a 6.5 inch jam)? Then apply the trim with a 1/4 inch reveal?
- Since this is not new construction, how would you suggest flashing? (Make a pan for the sill? What about the jams and header? Put the flashing over the siding and then apply the trim?)
- Suggestions for insulating between the frame and the R.O. (fiberglass, expaning foam?)
I’ve looked a the Marving installation instructions and called the rep, but they don’t have any particular suggestions–although they were nice enough…
Thanks for the suggestions!
Replies
Will you be replacing the siding? Typically, housewrap, felt or similar material goes on the sheathing, followed by the windows and their trim. Flashing then goes over the top of the window trim. Finally the siding butts up to the window trim and flashings. In this example, the window jambs (plus extensions, if used) are deep enough to go from the surface of the sheathing into the surface of the interior drywall.
It might be a good idea to create a real sill at the bottom so water drips free of the siding.
Al Mollitor, Sharon MA
MojoMan--
The siding in one of the few remaining details that the previous owners didn't screw up. Actually it had been cover first in asphalt siding material and then stucco and when both were removed, the siding was in very good condition...So to answer your question, the siding will not be removed--thus my quandry....What is the best way to deal with this situation...Thanks for the input..
Since your siding is staying on, Shep is right: Slip some felt behind the siding. This is not always easy to do without cracking the siding, but it's the right way to do it. Pay attention to detail at the bottom of the window. Try to apply your flashing so water won't get behind the siding.
Al Mollitor, Sharon MA
PNUTIII-- let me give you my ideas on how to accomplish what you want.
1. Install the windows so that the jambs are even with the exterior sheathing, then rip extension jambs to bring it even with the sheetrock. Try to make the extensions as flush as possible with the interior walls, it will make trimming the wimdows a lot easier. Depending on the reveals in the rest of your house, 1/8" to 1/4" would be fine.
2. The siding should already be pretty much ready for flashing, if it hasn't been butchered by the former occupant. I'd slip a 30 # tarpaper spline behind the siding up the sides of the window to seal the joint between the siding and ext. casing. You don't really need a pan to flash the sill; properly installation will take care of any problems here. The head casing should be flashed separately. Bend a piece of aluminum or copper to the correct size, slip it up under the siding directly above the window, and install the ext. head casing ( and wood drip cap, if appropriate).
3. you can use either fiberglass or expanding foam. Be careful with the foam. I've seen it pumped in so tight that the windows wouldn't work. Actually, I've seen that with fiberglass, too. Fiberglass is a little more forgiving, and less messy, to install. If you do go with the foam, install braces inside the window jambs to prevent them from bowing in.
4. Back to the ext. casings- remember to prime the back sides of the casings before installation. Your finish paint job will last a lot longer.
Good luck- it sounds like you've got a big project ahead of you, but it should be worth it in the end.
One thing I have found on this type of job--where the siding is staying put--is to center your window as much as possible side to side with where the siding is cut--not with the wall framing. While you might not be able to center it perfectly, this will leave you with almost equal width side casings--don't assume the old window was centered in the opening when the siding was originally installed. You might end up with casing that is of very apparently different sizes if you center the new window in the frame opening. To see this, mark a center point for the frame opening, then mark the center point between where siding is cut on each side---likely not the same point. Also, if possible use a low-expanding foam (Great Stuff Blue) made for door and window frames. Also, make sure the old weight pockets are closed up and/or insulated.
I have used foam for lots of stuff and I really like it. If you think that after it's cured that your to tight you can adjust it by using a sawzall blade by hand and cut the foam, each pass cuts the thickness of the blade. Fine tooth blade a little, coarse wood blade more. This has always resolved any to much foam problem with window install.
Clay