I have an old (1820’s) post and beam farm house in Vermont. We have been in the house 3 years and are trying to right the wrongs of several generations of neglect.
Roof is 12/12 Gable end, rafters are approx 6″ timbers on approx 5′ centers, hewn on three sides, Sheathing is 1x pine, no ridge beam. Roofing is 2-3 layers of cedar and asphalt shingles. Half of the attic is finished as living space with little or no insulation. Other half is open attic with no insulation.
I need a new roof and would like to add some insulation. Here is a plan and I would like some feedback. 1. strip roof back to sheathing. Repair sheathing as required. 3. Lay tar paper 4. Lay 2×4 sleepers hortizontally to provide space for foam board and provide level surface (with shimming as needed) for roofing. 5. Lay steel roofing as final layer.
I do not know the drawbacks of such a plan, but see this as a way to easily get some roof insulation where there is none. Put on a long lasting roof material and straighten a wavy looking settled roof.
Thanks in advance for your help and ideas.
Replies
I recently roofed a log cabin that had basically the same situation. In this case a rigid foam (3 1/2") with osb attached to the top side was used. Taller rake and fascia boards were installed to cover the edges. I just applied the roof after this was done, so I don't know the manufacturer, but I've seen several systems like this advertised.
Tear off everything. Start from scratch, new rafters etc.etc.
Save the old log/rafters and build a barn or shed with them.
Yeah, I agree. I didn't catch the 5' centers the first time.
Ouch, it is easy to say "start from scratch" when I am the one doing the work. hahaha
Actually, I had thought about that (and agree) for several reasons, but ended up regecting the notion that if I threw enough money and time at this house it would become a grand old house. Right now I am in the "good enough" or keep it simple mode, but will look into redoing the entire roof. Could accomplish several "might-as-well-as" tasks at the same time.
given the context, I would run the foam panels solid instead of breaking them around 2x4s and inviting draft/condensation problems. With the foam in place you can sheath over it with osb or ply and use long structural screws to fasten it to the under sheathing. I use the Reiser screws by GRK of Canada with a torx bit head. They are self drilling and have a self countersinking bugle head.
The tarpapre and shingle.
Excellence is its own reward!
don, you do not say if 1. you wish to keep the rafters exposed on the inside when finished. 2. the overall condition of rafters and roof sheathing. and 3. how much insulation/R-value you are trying to achieve.
answers to these questions will result in different options, especially for you as a solo carpenter.
david
walk good
David, (and others)
Rafters are in good condition. Sheathing is old W I D E pine and in the unfinished part of the attic it looks serviceable but not attractive. It would not be usefull for anything other than its current task (recycled to flooring, etc). The rafters do not need to stay exposed (and they are not in the finished half). But it would be nice to leave them exposed if I replace the sheathing and first put down tongue and groove or beaded boards as the finished ceiling. Ideally I'd like an R-factor in the 30's as it does get cold from time to time in Vermont. Here are some other factors that could influence the final plan.
1. The house is 20 ft deep. This puts the peak of the roof at 10 feet and leaves a narrow section down the center of the attic that a 6 footer can stand tall.
2. I would like to use the attic as living space but would like some more head room.
3. There is an 8 foot wide add-on enclosed porch along the front. I have thought from time to time about setting some posts in a good foundation at the corners of the porch and then building a new gable end roof from the porch front to the back. This would make the attic 28 feet deep and with a 12/12 pitch and a 7' ceiling, give me 13-14 feet of headroom space. I could later rebuild the porch to add it to living room space.
4. There is only one roof penetration right now. (2'x2' chimmney) Sewer vents were run up the side of the house. Roof removal is potentially about as easy as it could get. Not counting a benevolent tornado or a huge check book.
I am caught between lots of hard work and money to make this house something it never was vs. make it good enough and build a new house if I really want tall ceilings, no drafts and straight walls. The house is in a good place with lots of elbow room and good neighbors so I don't have other reasons compelling me to just move on. Am also truely stubborn once I get a idea in my head and not afraid of hard work. So there ya have it. Oh yeah, money is a factor.
I do appreciate everyones time and comments on this.
Edited 4/13/2002 6:24:03 PM ET by Don
Don, my thoughts on your reconstruction.
With a 12/12 pitch your usable space for ####second floor is about 10-12 feet wide, centered on the peak. I would drop a knee wall at the 48 inch heigth from both walls of rafters. You can use it as storage or close it off. It is unusable as living space and would allow you rto insulate more wall space than rafters.
For the remaining sloped rafter area inside the newly defined living area, you can nail 2x12 to each side of the existing rafter and then run 2x6 perpendicular to form the new ceiling. At the 8 foot heigth, I would run horizontal ceiling joists. This allows excellent insulation cavity even if using fiberglass batts.
Before doing any framing, I would staple up red rosin paper to the underside of the existing sheathing to serve as a wind barrier and to facillitate using blown-in if that be your choice ( my choice is blown-in cellulose).
To make more room in the space ypou could add a dormer, evern one between the existing rafters would greatly increase the space and feel of space. All this is doable as you are planning on stripping the roof. I like your idea of a metal roof on the existing sheathing. If it is a delta rib type with the ability of air flow then you need to do nothing to your existing sheathing. If you use a flat panel metal roofing, then you will need to accomadate airflow on the underside of your existing sheathing.
Sounds like a project. What part of Vermont are you in?
david
walk good
David,
Thanks for the info. Thetford. About 15 miles north of White River Junction and Lebanon, NH.
Don