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riverandwoods
insulating room addition.

I am in the middle of a project which added a 12X18 foot kitchen to my existing house. The room is partially built under an existing porch. I added a shed roof over the existing roof. Recognizing the need for ventilation and insulation, my dilemma is how to best handle the portion of where the existing roof is covered by the new roof. It seems like I'll get heat build up in that area between the two roofs if I don't provide some ventilation at the top most juncture of the new roof and the old roof. Clearly, where the ceiling is I need some ventilation out to the eave. Question make sense?

I'm in far northern Wisconsin, where temps can range from 90's down to the -30's.

Any advice?

MtMan54
Re: insulating room addition.

Hi, Insulating starts with the framing because you can't put 2 feet of insulation in a 3 1/2 inch space. You need to have installed a attic platform before you install the roof. This platform needs to be the full depth out over the walls and the roof attached on top of the attic platform. Thanks

dj1
Re: insulating room addition.

Did you pull a permit for this job, do you have plans for this job?

Approved plans would have given you all the answers.

riverandwoods
Re: insulating room addition.

No permit required in my town. I did have an architect help with the design. But the plans are more conceptual than detailed.He did not provide details at the juncture of the two roofs. The plan is to insulate above ceiling, provide ventilation at the end of the old roof and then cut vents as high up in the old roof as possible, to that no hot air is trapped in the space between the two roofs. Make sense?

MtMan54
Re: insulating room addition.

Hi, I would add enough insulation to keep the hot air inside the house but I can see that you want to vent it to the outside. Thanks

riverandwoods
Re: insulating room addition.

I plan on R38. I'm certainly cognizant of the need to have sufficient insulation, given the length of winter here. I recognize the potential for ice dams, but I'm more worried about the summer heat building up in the space between the two roofs, which is why there is a need to vent that portion. My thought is providing equivalent ventilation area by using my sawsall or hole saw to penetrate the highest point where the two roofs come together, so that the heat has the opportunity to use the ridge vents at the peak of the roof on the main house. I'll also need to cut back the portions of the old roof at the point where it used to end at the original eave.

MtMan54
Re: insulating room addition.

Hi, There is another way to vent without cutting holes in the attic. You can vent the roofing but not the attic. You can add a grid of strapping under the roofing before it is installed. Thanks

MtMan54
Re: insulating room addition.
riverandwoods wrote:

I plan on R38. I'm certainly cognizant of the need to have sufficient insulation, given the length of winter here. I recognize the potential for ice dams,

Hi, You may plan on R38 but to get 1 foot of insulation, it needs to be over the walls. R38 in the middle will not do the job. If there is not 1 foot of space between the bottom of the rafters and the top of the walls, you may only have R11 in the attic. This is why you need an attic platform to attach the rafters to. Thanks

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