How to build a gabled roof on a rigid insulation roof?
Hello to all at this forum. Back in 2013 I posted on my garage build here….
Since a few months now I had started doing some work on my home to increase the insulation value.
I am including a photo of how it is today just before we add the roof sheathing, but I am sort of stuck on how to include a gable roof on each end of the house.
I have been taking time lapse videos and regular videos during the complete process. This is much harder then building a new garage where everything is really under your control. Retrofitting a home is chock full of those endless and time consuming details.
I have included a photo of my original house and one photo of where I am now. What prompted the change is many fold. The shingles were going bad (due for a BP refund), the windows, front door and patio door needed to be replaced, the house siding was pretty worn down, but the greatest problem stems from the actual design of the home itself. As you can see the front gable roof is directly over an area that protrudes out from the main wall and this type of design does not permit having a working soffit along that area. This causes a major dead air space in the attic that gets so hot during the summer that the rooms in that area become very uncomfortable or air conditioning is required continuously at maximum.
There is also that my new garage now has a new brick and future siding look that does not match the house. .So these are good reasons to take the plunge so to say.
My garage is perfect. During the dead of winter at -30 Deg.F, I shut off all power to the garage for one whole day and the internal temperature dropped 2 degrees. I did not try this with my house but I am sure it would have been -30 after one whole day without electricity.
The other main reason for these changes is when I starting looking into HVAC alternatives for the home as is, that is with very limited insulation in the attic given a 4.25/12 pitch of the roof left no head room for increasing insulation depth at the eaves. Most HVAC guys wanted to install a central unit in the attic as it was. When I asked them about how the equipment will fair trying to air condition the home during the summer while it is in a super hot attic, or, how it will heat my home during the winter while the attic is dead cold. They all said the unit is insulated but I found out it is no better then R10. So these guys wanted me to dish out a good 24 grand while providing meager efficiency. So it was time to make a move once the studying was done. A year later and this is where I am today. hahaha 30 pounds lighter to boot.
The 2nd photo is a collection of shots of where I am at right now. (please excuse the photo quality)
The third is a diagram I made to better explain what I did.
With the roof now covered by 8 inches of rigid insulation and held down by real 2 by 4s and 12″ screws (we found a way to increase our odds at landing on the trusses below), I am curious if there is a good way to include a 24 inch long gable roof at each end. Since the roof is now configured to provide 42 air channels of 2″ by 20″ each, I cannot build the gable lookouts in the regular manner since this will block the air movement in 8 of these air channels and for me, that seems unacceptable.
I guess I am just over worried about the gable ends not being strong enough to meet its task. The only way I can see to do this is to add 2 x 12s along the gable wall held with some bolts into the first roof trusses (gable truss) so it will reach right flush with the top of the 8″ insulation on the roof. This would provide an anchoring for the lookouts but maybe going out 24″ would be to long.
I have been at this for the last 3 months what with rain delays and all. During the initial “demolition” I had a 20 cubic meter container full to the top, weighed out at 5.7 tons when it left. Because of the high level of labor intensive work involved, I did most of the work myself especially those finer details, and had hired my son and a few friends on some days for more specific labor intensive tasks. Such a project is definitely not for the faint of heart and at 58 years young, this project has really pushed me to my limits in terms of physical demands. But I had no choice since the costs to delegate the whole project to a general contractor would have been prohibitive and anyways, there are no contractors that would have done what I did. hahahaha
Just as in my garage build where I set a goal to prepare all the foundations (footing, wall, slab and driveway) so that it receives only one concrete pour (done successfully), my challenge for the house was to make sure all the wood framing of the house itself is covered by insulation so as to provide a full thermal break. This has been successful and the house is now what many would call very close to the Persistent method.
Terrebonne, Quebec, Canada
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