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I’m a frequent reader here, finally coming up to ask a question. I’m interested in visual techniques for disguising a thick roof resulting from the use of a thick layer of exterior foam insulation.
We’re building a greatly overdesigned 9×18 workshop/potting shed here in coastal NC; it’s not “just a shed” to us. It has a cross-gable roof design and we want an attractive interior with exposed rafters and planking (not plywood) with a cathedral ceiling. On the walls, the hurricane codes will not less us get away with using planking instead of plywood, so I’ll put beadboard inside and sacrifice the use of the stud cavities.
On the roof, however, the building inspector has grudgingly approved horizontal planking (1×4) as the decking. This will be covered with a vapor barrier, 3″-4″ of polyiso foam insulation, furring strips, plywood, and metal roof. The exact configuration here might vary a bit depending on the insulation I select and the manufacturer’s recommendations (e.g., I might go with nailbase).
Our home is an old craftsman bungalow and we’d like the shed, er, workshop to match, with nice deep gable overhangs and exposed rafter tails. The overhangs will also help with our summer heat and, on one side of the shed, provide protection for the toys (kayaks). My dilemna has been how to provide these overhangs without the look of a wicked thick roof. If we find a good solution, we may use this whole method in the future to insulate our house attic, which has really nice plank decking we would like to keep exposed.
I THINK I found a great solution in a FHB article (FHB 130, page 108, “Building a New Cottage to Look Old”). On this cottage, it seems they made separate rafter tails, attached the tails to an extra-wide fascia on the ground, and installed the entire fascia as one unit after the fact. This essentially raises the rafter tails up so that only the thickness of the roofing and plywood actually extend into the overhangs, and the tails look like normal rafters. This roof doesn’t look thick at all. The fascia appears to be wider than normal, but only on close scrutiny.
The gable overhangs / barge (ladder?) rafters also look very normal, but I don’t see details in the article about how they rigged those. With the lookouts coming off the rafters, the roof would still appear thick at these gable ends. So … could the furring used to separate the insulation and metal roof be extended out to double as lookouts to support the barge rafters, if the furring strips were beefy enough? Or would be it better to attach the lookouts to the fascia and again assemble as one decorative unit? My concern is uplift — if the furring extends out, then it seems there would be more potential for uplift there. If all overhangs are basically “decorative” as separate units, would it be better or worse from an uplift perspective? Seems they could come off easier, but would have less effect on the integrity of the whole roof assembly.
I want to have some good sound ideas before I run these plans by the building inspector — he seems open to my ideas because I’ve researched them so thoroughly and can speak to the pros and cons. What are your thoughts on this? Has anyone used other methods to disguise the thick roof?
I’ll take some digital photos and post the URL for y’all later today.
Pam
Replies
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I'm a frequent reader here, finally coming up to ask a question. I'm interested in visual techniques for disguising a thick roof resulting from the use of a thick layer of exterior foam insulation.
We're building a greatly overdesigned 9x18 workshop/potting shed here in coastal NC; it's not "just a shed" to us. It has a cross-gable roof design and we want an attractive interior with exposed rafters and planking (not plywood) with a cathedral ceiling. On the walls, the hurricane codes will not less us get away with using planking instead of plywood, so I'll put beadboard inside and sacrifice the use of the stud cavities.
On the roof, however, the building inspector has grudgingly approved horizontal planking (1x4) as the decking. This will be covered with a vapor barrier, 3"-4" of polyiso foam insulation, furring strips, plywood, and metal roof. The exact configuration here might vary a bit depending on the insulation I select and the manufacturer's recommendations (e.g., I might go with nailbase).
Our home is an old craftsman bungalow and we'd like the shed, er, workshop to match, with nice deep gable overhangs and exposed rafter tails. The overhangs will also help with our summer heat and, on one side of the shed, provide protection for the toys (kayaks). My dilemna has been how to provide these overhangs without the look of a wicked thick roof. If we find a good solution, we may use this whole method in the future to insulate our house attic, which has really nice plank decking we would like to keep exposed.
I THINK I found a great solution in a FHB article (FHB 130, page 108, "Building a New Cottage to Look Old"). On this cottage, it seems they made separate rafter tails, attached the tails to an extra-wide fascia on the ground, and installed the entire fascia as one unit after the fact. This essentially raises the rafter tails up so that only the thickness of the roofing and plywood actually extend into the overhangs, and the tails look like normal rafters. This roof doesn't look thick at all. The fascia appears to be wider than normal, but only on close scrutiny.
The gable overhangs / barge (ladder?) rafters also look very normal, but I don't see details in the article about how they rigged those. With the lookouts coming off the rafters, the roof would still appear thick at these gable ends. So ... could the furring used to separate the insulation and metal roof be extended out to double as lookouts to support the barge rafters, if the furring strips were beefy enough? Or would be it better to attach the lookouts to the fascia and again assemble as one decorative unit? My concern is uplift -- if the furring extends out, then it seems there would be more potential for uplift there. If all overhangs are basically "decorative" as separate units, would it be better or worse from an uplift perspective? Seems they could come off easier, but would have less effect on the integrity of the whole roof assembly.
I want to have some good sound ideas before I run these plans by the building inspector -- he seems open to my ideas because I've researched them so thoroughly and can speak to the pros and cons. What are your thoughts on this? Has anyone used other methods to disguise the thick roof?
I'll take some digital photos and post the URL for y'all later today.
Pam