Retro insulating a cathdral church roof
jimcco
| Posted in Construction Techniques on
A friends’ church is needing to be reroofed and they are interested in improving the insulation over the sanctuary. This is 3×6 tongue & grove deck running perpendicular to laminated arch beams. The only insulation is 1″ foam board between the deck and 1/2 plywood sheathing.
Has anyone here had any experience trying to add something to the exterior of this?
Adding to the underside is not an option as the 3 x 6 is the exposed ceiling.
Replies
I have a house which has the roof decking of 1 1/2" homosote which was the only insulation. The inside is exposed beams and rafters and we wanted to preserve the look. We added 3 1/2" of rigid insulation on the top of the homosote (after stripping the roofing). On top of that 1/2" plywood with long screws to reach the rafters. As the rafters are 30" on center an intermediate set of shorter screws was driven in to bite into the homosote as well. Facia was reworked. I expect a lot less fuel use this winter. Why not remove the plywood and replace the 1" with something like 4" and then ply and roofing?
Edited 11/5/2009 7:06 pm ET by 7Joel
They could use a rigid insulation panel with an OSB or ply face attached to one side. Sort of a SIPS panel, but with the sheathing only on one side.
I'd strip the roof down to the T&G, and start from there. Screw the panels to the existing roof sheathing with long screws, then install the new roofing.
They'd also have to make all the fascias and rakes wider, to cover the edges of the panels
I know they're available in different thicknesses. You'd have to determine what R-value you want, and go from there.
I have heard of guys using a Styrofoam insulation with plywood over it with long nails or screws into the 2X6 cedar ceiling. Make sure the screws do not go right through as you will see them on the inside.Or insulate on the underside fo the roof and cover with ceiling of choice.Just last year did an old church like this. Had cinder block walls. We put Styrofoam on the walls then concrete crewed on 1X4 strapping then put metal on it. It was the side close to another building that no one really sees. They did not want the expense of sheeting it and siding it.I have since seen Styrofoam with 1x2 embedding into it.