It seems the new guy gets the work that the vets don't really want. The past two weeks I have been working overhead, on scaffolding, doing work that is less than exciting. We built a framework / substructure for the soffit and fascias using 38mm x 50mm treated S.A Pine. The soffits and fascias are fiber cement boards commonly called 'Nutec' (one of the brand names). These are best cut by the supplier, but since this is a renovation of a 100 year old house, the walls are irregular and we had to cut them on site with an angle grinder fitted with a diamond blade. I took measurements at 3 points for each 2.4 m length and custom cut each soffit board to fit neatly against the irregular walls. There really isn't a countersink tool suited for masonry so each heavy soffit board had to be cut, held in position, marked for screw holes, then taken down and drilled with a small pilot and larger countersink and then fitted in place. It is a time consuming process with a lot of climbing up and down scaffolding. It was a nightmare on days when I only had one assistant. With an overhang of 500mm, the 9mm boards are quite heavy. 3 guys are required for installation.
I would love to explain a few of the challenges that I ran into due to the non-traditional design of this roof, but they really require a look at the plans or photos to be understood. There are no available detail drawings and the plans don't show the necessary detail, so there was a lot of troubleshooting along the way.
I noted a few things that could be done differently in future to save us from frustration and things that differ to what i have seen in Canada and England.
One example is the hoop iron tie-down used to hold the rafters down to the brick walls. This is sometimes done with wire or with hoop iron and doesn't interfere much with the purlins or battens to which the tiles or sheets are fixed. In this case, however, the architect specified battens running along the top edge of each rafter holding the membrane in place and creating more space between the membrane and tiles. The hoop iron is 2mm thick and when bent over the angled rafter it protrudes another couple of mils. After the membrane was rolled out and we struggled to fit the battens flush to the rafters we had to pound all the tie-downs as flat as we could to get an acceptable result. I would have made two little cuts across the top of each rafter about 5mm deep. The space between these cuts can then be hit with a hammer and a very neat tidy channel will result so that the hoop iron could fit in below the top edge of the rafters.
I would love to explain a few of the challenges that I ran into due to the non-traditional design of this roof, but they really require a look at the plans or photos to be understood. There are no available detail drawings and the plans don't show the necessary detail, so there was a lot of troubleshooting along the way.
I noted a few things that could be done differently in future to save us from frustration and things that differ to what i have seen in Canada and England.
One example is the hoop iron tie-down used to hold the rafters down to the brick walls. This is sometimes done with wire or with hoop iron and doesn't interfere much with the purlins or battens to which the tiles or sheets are fixed. In this case, however, the architect specified battens running along the top edge of each rafter holding the membrane in place and creating more space between the membrane and tiles. The hoop iron is 2mm thick and when bent over the angled rafter it protrudes another couple of mils. After the membrane was rolled out and we struggled to fit the battens flush to the rafters we had to pound all the tie-downs as flat as we could to get an acceptable result. I would have made two little cuts across the top of each rafter about 5mm deep. The space between these cuts can then be hit with a hammer and a very neat tidy channel will result so that the hoop iron could fit in below the top edge of the rafters.
Another thing that I noticed was that the timber floor joists didn't have noggins / blocks between them. The joists span about 3 meters. Since these joists were 228 x 50 they are a little less likely to twist than a thinner board, so that may be why they are not used. The subfloor is osb (oriented strand board) and each long butt joint lies along a joist, the short butt joints, however, are not completely supported as they cross from joist to joist. It seems possible to me that there could be movement at those joints. In Canada and England a tongue and groove osb system is used for the subfloor so all joints are locked. We also glue every board to the joists in addition to fixing them with screws. Swissline didn't install the subfloor on this house, but whoever did, didn't glue it.
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