05-16-2011, 01:59 PM
One of the biggest challenges, at least for me, when making a removeable roof is to ensure that it doesn't warp (and this applies just as much to styrene as it does to wood and cardstock) and to devise a way to hold it in place securely, yet still allow it to be removeable.
Both of these requirements are somewhat related, so the solution for one may also solve the other. One method is to add vertical stiffeners to the underside of the roof. On your structure, I'd suggest running them from door-end to blind-end. Make one to fit along each sidewall, and as deep as is practical without hiding interior framing detail - they should extend down at least to the top plate of studs on the exterior walls. Also, they should be positioned so that they make a snug fit inside the side walls and should be full-length so that they give a positive and repeatable method of replacing the roof in the exact same position every time.
I'd also add similar-size stiffeners at each row of support posts - make them as pairs, so that when in place, each of those longitudinal beams is trapped between a pair of them. The roof support rafters can then be cemented in place on the underside of the roof, perpendicular to the beams. Glued to both the underside of the roof and at their ends to the stiffeners, the roof should become relatively stiff and stable.
If you find that, even after all of this bracing is added, the roof still does not seat properly, drill suitably-sized and -located holes through the exterior walls and through the stiffening webs, then add wire pins or brass nbw castings (representing tie rods) to hold the roof in position. Make them a snug fit to keep the roof in place, yet still allow it to be removeable merely by removing the pins/nbws.
Wayne
Both of these requirements are somewhat related, so the solution for one may also solve the other. One method is to add vertical stiffeners to the underside of the roof. On your structure, I'd suggest running them from door-end to blind-end. Make one to fit along each sidewall, and as deep as is practical without hiding interior framing detail - they should extend down at least to the top plate of studs on the exterior walls. Also, they should be positioned so that they make a snug fit inside the side walls and should be full-length so that they give a positive and repeatable method of replacing the roof in the exact same position every time.
I'd also add similar-size stiffeners at each row of support posts - make them as pairs, so that when in place, each of those longitudinal beams is trapped between a pair of them. The roof support rafters can then be cemented in place on the underside of the roof, perpendicular to the beams. Glued to both the underside of the roof and at their ends to the stiffeners, the roof should become relatively stiff and stable.
If you find that, even after all of this bracing is added, the roof still does not seat properly, drill suitably-sized and -located holes through the exterior walls and through the stiffening webs, then add wire pins or brass nbw castings (representing tie rods) to hold the roof in position. Make them a snug fit to keep the roof in place, yet still allow it to be removeable merely by removing the pins/nbws.
Wayne