Next step was making everything if not watertight then at least better protected against the near continuous stream of water falling out of the sky, or so it seemed.
Now that is in two parts, the roof and the walls - I know, blinding flash of the blinking obvious there! But having said that the essential difference between the two is the insulation. I hope to be spending a considerable amount of time in the workshop including in the colder months (not least because at the moment I have a seasonal summer job that I enjoy a lot but less secure employment during the winter months) and I want to keep heating costs down. Plus of course, although the obvious solution to heating is just a small fan heater from Screwfix put on for a quick blast in the morning when I go out to the workshop that means the machine tools and unfinished workpieces will be in an unheated environment with the potential for condensation and worst case rust issues. So insulation in the roof above the OSB sheeting, and insulation in the walls inside the sheeting in the space between the 2x4s (plus a bit more but I will get to that.)
Basic warm roof - from the inside out , roofing layer of OSB as last time, thermal vapour barrier, 25mm PIR foam, second layer of OSB, then an extra layer to protect the OSB and act as underfelt and finally, a bit of an extragavance I admit, asphalt shingles. Roofing felt would have done an equally good job but I prefer the look of the shingles and they should last a lot longer than basic felting. The roof slope is right at the bounds for the use of shingles though but with a bit of extra care I think it should be OK, I guess time will tell.
Ideally the roof insulation should be thicker than 25mm but being limited by the standard height restriction of 2.5m 25mm of PIR foam is the maximum usable. Should it turn out to be inadequate then in the future extra insulation can be fitted inside between the rafters.
The other consideration is of course light. The workshop basically runs east west (long axis) with the double doors at the east end and the side door in the south side. I want, well given the size of the workshop need, solid walls for storage cupboards, racking etc so the roof will be the major source of natural light, with maybe a few small windows in the doors eventually. The issue then becomes not just potential heat loss through the roof windows but also potential solar gain in summer through the south facing side of the roof. Also as far as possible it's easier building to have equal roof thickness on both the north and south faces of the roof. Hence solid roof as described above on the south facing side and at the end bays between the end pair of rafters with 35mm multiwall polycarbonate for the rest of the roof on the .north facing side.
Roofing started with reflective thermal vapour barrier first (Superfoil SFTV) and 25mm edging strip round the roof to keep the PIR foam in place. And before anyone asks yes, I did put extra 2x4s inside as supports for the main roof beam whilst working on the roof. I'm not that .... (fill in the blank for yourself).
Then the outside layer of OSB on top, through screwed into the rafters inside
Do all the south facing roof then cover with waterproof shield barrier and start shingling. Of course the shingles only cover the upward facing part of the roof so to give decent edge protection I started with a narrow strip of felt roof edging strip just to wrap round the roof edge and return under the outside eaves, not only creating a waterproof edge but also giving a drip edge. It also obviated the need for a layer of cut off shingles at the bottom edge of the roof.
Doing the actual shingling really wasn't that bad I found, just a question of taking care to keep the line straight and working systematically on both the south face and the end parts of the north facing roof.
On the north, windowed side of the roof to equalise the thickness meant first cutting strips of spare OSB to go on the top of the rafters, then fitting the seals for the glazing on top of that. Having not done this sort of thing before I took the advice of the supplier about the overlap on the rafters needed and had the polycarbonate sheets supplied cut to size. Additionally having them pre-cut to size meant they came with waterproof tape at the top end and breatable tape at the lower end pre-installed. Much easier than cutting them myself and not much extra cost. If you look closely you can see the OSB strip under the seal. Note also that at the far end of the roof the end bay already has the same build up as the other side except for the shingling
The roof glazing panels were installed from inside the workshop just lifting them through and laying them in place then using the top glazing bar with the appropriate seal screwed through into the rafter to hold everything in place. Getting glazing bars suitable for 35mm multiwall sheeting did take a bit of searching online, the typical snap in plastic glazing bars don't come in the thicker spec so it had to be metal strip with rubber edge seals fitted screwed through with a dab of silicone sealant on the screws and then caps tapped in place to cover the screws.
The top seals which lie under the glazing bars create the necessary waterproofing between the roof lights and building up the end bays to the stage of having the outer membrane covering on but not shingled gave a plain smooth surface for the seals on the glazing bars to mate to avoiding gaps which could allow water in. I admit to running a bead of flexible silicone down the outer edge as belt and braces insurance though Along the top edge of the glazing, to ensure a waterproof seal preventing water penetration between the top of the glazing and the roof ridge I ran a strip of self adhesive lead flashing. A bit of a pain in the neck getting it to seal but a seam roller for wallpaper helped a lot getting it rolled down flat - tip, don't do it cold, it gets much more flexible warm. Then it was simply a question of shingling the end bays.
Shingling all the way to the apex of the roof just left a slightly overlapping seam of shingles to be covered with a strip of roofing felt and all joins are covered. Again, as belt and braces against capillary action under the shingles and wind damage I also tacked the edges of the shingles down with felt roofing adhesive as I went along.
And since there is a nice strip of felt along the ridge, why resist a bit of a decorative touch at the ends? The excess shingles sticking out a bit on the left I later trimmed with a knife.
And after all that, I think it turned out pretty well, many thanks to my assistant, and since then, it has turned out to be waterproof and let's plenty of even light in.
Outside of the walls next, a lot simpler, well, to begin with .... but next time
Now that is in two parts, the roof and the walls - I know, blinding flash of the blinking obvious there! But having said that the essential difference between the two is the insulation. I hope to be spending a considerable amount of time in the workshop including in the colder months (not least because at the moment I have a seasonal summer job that I enjoy a lot but less secure employment during the winter months) and I want to keep heating costs down. Plus of course, although the obvious solution to heating is just a small fan heater from Screwfix put on for a quick blast in the morning when I go out to the workshop that means the machine tools and unfinished workpieces will be in an unheated environment with the potential for condensation and worst case rust issues. So insulation in the roof above the OSB sheeting, and insulation in the walls inside the sheeting in the space between the 2x4s (plus a bit more but I will get to that.)
Basic warm roof - from the inside out , roofing layer of OSB as last time, thermal vapour barrier, 25mm PIR foam, second layer of OSB, then an extra layer to protect the OSB and act as underfelt and finally, a bit of an extragavance I admit, asphalt shingles. Roofing felt would have done an equally good job but I prefer the look of the shingles and they should last a lot longer than basic felting. The roof slope is right at the bounds for the use of shingles though but with a bit of extra care I think it should be OK, I guess time will tell.
Ideally the roof insulation should be thicker than 25mm but being limited by the standard height restriction of 2.5m 25mm of PIR foam is the maximum usable. Should it turn out to be inadequate then in the future extra insulation can be fitted inside between the rafters.
The other consideration is of course light. The workshop basically runs east west (long axis) with the double doors at the east end and the side door in the south side. I want, well given the size of the workshop need, solid walls for storage cupboards, racking etc so the roof will be the major source of natural light, with maybe a few small windows in the doors eventually. The issue then becomes not just potential heat loss through the roof windows but also potential solar gain in summer through the south facing side of the roof. Also as far as possible it's easier building to have equal roof thickness on both the north and south faces of the roof. Hence solid roof as described above on the south facing side and at the end bays between the end pair of rafters with 35mm multiwall polycarbonate for the rest of the roof on the .north facing side.
Roofing started with reflective thermal vapour barrier first (Superfoil SFTV) and 25mm edging strip round the roof to keep the PIR foam in place. And before anyone asks yes, I did put extra 2x4s inside as supports for the main roof beam whilst working on the roof. I'm not that .... (fill in the blank for yourself).
Then the outside layer of OSB on top, through screwed into the rafters inside
Do all the south facing roof then cover with waterproof shield barrier and start shingling. Of course the shingles only cover the upward facing part of the roof so to give decent edge protection I started with a narrow strip of felt roof edging strip just to wrap round the roof edge and return under the outside eaves, not only creating a waterproof edge but also giving a drip edge. It also obviated the need for a layer of cut off shingles at the bottom edge of the roof.
Doing the actual shingling really wasn't that bad I found, just a question of taking care to keep the line straight and working systematically on both the south face and the end parts of the north facing roof.
On the north, windowed side of the roof to equalise the thickness meant first cutting strips of spare OSB to go on the top of the rafters, then fitting the seals for the glazing on top of that. Having not done this sort of thing before I took the advice of the supplier about the overlap on the rafters needed and had the polycarbonate sheets supplied cut to size. Additionally having them pre-cut to size meant they came with waterproof tape at the top end and breatable tape at the lower end pre-installed. Much easier than cutting them myself and not much extra cost. If you look closely you can see the OSB strip under the seal. Note also that at the far end of the roof the end bay already has the same build up as the other side except for the shingling
The roof glazing panels were installed from inside the workshop just lifting them through and laying them in place then using the top glazing bar with the appropriate seal screwed through into the rafter to hold everything in place. Getting glazing bars suitable for 35mm multiwall sheeting did take a bit of searching online, the typical snap in plastic glazing bars don't come in the thicker spec so it had to be metal strip with rubber edge seals fitted screwed through with a dab of silicone sealant on the screws and then caps tapped in place to cover the screws.
The top seals which lie under the glazing bars create the necessary waterproofing between the roof lights and building up the end bays to the stage of having the outer membrane covering on but not shingled gave a plain smooth surface for the seals on the glazing bars to mate to avoiding gaps which could allow water in. I admit to running a bead of flexible silicone down the outer edge as belt and braces insurance though Along the top edge of the glazing, to ensure a waterproof seal preventing water penetration between the top of the glazing and the roof ridge I ran a strip of self adhesive lead flashing. A bit of a pain in the neck getting it to seal but a seam roller for wallpaper helped a lot getting it rolled down flat - tip, don't do it cold, it gets much more flexible warm. Then it was simply a question of shingling the end bays.
Shingling all the way to the apex of the roof just left a slightly overlapping seam of shingles to be covered with a strip of roofing felt and all joins are covered. Again, as belt and braces against capillary action under the shingles and wind damage I also tacked the edges of the shingles down with felt roofing adhesive as I went along.
And since there is a nice strip of felt along the ridge, why resist a bit of a decorative touch at the ends? The excess shingles sticking out a bit on the left I later trimmed with a knife.
And after all that, I think it turned out pretty well, many thanks to my assistant, and since then, it has turned out to be waterproof and let's plenty of even light in.
Outside of the walls next, a lot simpler, well, to begin with .... but next time
