Retrofit planning
Retro or not
My wife and I are thinking about removing our old three-tab roofing and having a steel roof installed.
We are located in Oregon in a Cape style house. We have a large number of trees close and around our house. We fight bad roof moss every year. About a month ago I was repairing a patch of dry rot, discovered termites, and then discovery of prior questionable repairs. So I removed all of the siding on the house to check for dry rot and such. The siding had been on since 1944 and needed some major repairs. We have been talking about a deep retro fit, were thinking about adding 4 inches of rigid foam and a lattice grid on top of the foam to the roof and 2 inches to the wall. We also want to extend the roof lines as well.
My question has to do with the sequence and which should be done first. If we add 4 inches of foam to the roof I will have at least 3 windows that will need to be raised up by reframing and installing shorter windows. The current roof is making contact with the window trim already. Can the gables and trim be extended after the roof has been completed; making sure the roofer extends the rigid foam to the correct distance. If not, does anybody have suggestions on how to match up the surfaces of the roof sheathing and the extensions while the 3 tab is still installed?
Were both retired on a fixed income so I will do most of the work, but I fell off my old garage with a 8 in 12 pitch which is the same as our house so were going to hire a contractor for the foam and the metal roof. I will use a chicken ladder install the windows.
If you could recommend articles or books I’m very willing to research.
Thank you ahead of time!
Greg
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Replies
Greg,
Either approach will work -- walls first or roof first -- as long as your contractor anticipates the work to come.
For more information, see these three articles:
"How to Install Rigid Foam Sheathing"
"How to Install Rigid Foam On Top of Roof Sheathing"
"Installing Windows In a Foam-Sheathed Wall"
Thank you for your response Martin, I have been studying these three articles for the last month and half. All three are well written and are loaded with great information. I think I have my head wrapped around what needs to occur. I do have a few areas that I need some help on. First, none of the windows have been flashed. Some of the windows have a ½ gap between the window frame and the wall sheathing boards. 14 windows have been upgraded with vinyl insert replacement windows.
So I’m leaning towards treating each window as its on project. Remove the insert and carefully remove the head, jam and sill then remake them out of ¾ plywood, adding 2 more inches for the foam. Reinstall the inserts more to exterior of the new window frames kind of like an outie after the opening is flashed, I will be installing at least 9 new windows and want them to match as best I can.
Also this may be a no brainer, how do you handle a window that would be in the way of a roof extending down intersecting with a window opening? I’m going to put smaller windows in the upstairs to raise the bottoms up to make room for the roof. Do windows get lowered in a situation that the roof intersects a wall window opening, or is the window removed, down sized?
Martin, thank you for your time!
Gregory,
Unless you are looking for deeper window sills, removing and moving the windows should not be needed. You can take your existing sheathing as the WRB surface, flash your windows to this surface then add in trim to bring it out to the new siding surface. Take a look at Fig 49:
https://www.nrel.gov/docs/fy13osti/55219.pdf
I'm not sure I follow your roof window interference question above, maybe a picture will help.
For your upper story windows, if you don't want to replace them, you can get tapered rigid foam. This lets you cover most of your roof in foam and then taper down a bit before the windows if it is a question of an inch or so.
Your wall extending out further with the foam will also effectively raise your windows a bit, if it is a 6/12 roof slope going out 2" gets you 1" of height.