chappardababbar
Member
- Joined
- Nov 28, 2014
- Messages
- 62
Hi I’m thinking of undertaking a project this weekend that I’m unsure of and want to get some input from people on here. I have never done any woodworking before but this might be a good excuse to try the tools I’ve just bought. I think I can do it if the method is clear.
I need to build the upstands for 9 roof lights on a flat roof. 6 roof lights are 1200mm x 800mm and 3 roof lights are 1500mm x 1500mm.
I’m having problems with builders and I’m wondering if this is something I can do myself to expedite things…I’ll try my best to explain what it is I think I need to do then I’ll try to add some hand drawn sketches to better illustrate later today. Here is the requirements specification as I understand it
The total roof area is 8.5m x 8m approximately. The 8m length is the direction in which I need to achieve an inclination for rainwater(away from the house towards the garden)
The timber joists are in place and the apertures for the roof lights are ready
The roof is perfectly flat but I need a minimum 1 degree inclination. I have purchased firrings that are 8m in length and go from 200mm down to 0mm, this equates to around 1.3 degrees
The upstands need to rise 150mm above the flat roof
I think it’ll be easier to first build the upstands at 5 degrees and fix them directly to the roof joists rather than putting the firrings down first and subsequently fixing the roof lights into the firrings. This is because It’ll be more stable, I feel.
The problem with this approach is that it’ll be hard work to create the inclination: I’ll have to cut the firrings and fix them around the roof lights
Assuming I go down this route, the next problem is the construction technique for the upstand. The roof light diagram shows a cross section of 50mm thick timber on the inside with 18mm thick plywood on the outside. Plywood comes in sheets but timber comes in pre-cut sizes. I know I need 50mm (2 inch) but what height?
The firring is 20cm tall at it’s tallest point. On top of this will sit an OSB board (18mm), then either Fibreglass or roof felt (10mm?) That’s about 3cm in total so firring + roof covering = 23cm
If the upstand box needs to clear the roof by 150mm, then the tallest upstand needs to be 23cm + 15cm = 38 cm = approx 15 inches from the front…it then needs to be higher to the equivalent of 5 degrees at the back
I’m thinking I keep all the upstands exactly the same heights relative to each other so that from inside the house, when you look up they all look the same height. From the outside the upstands closer to the house will protrude around 150mm from the roof, those closest to the garden will extend more 38cm from the roof
I think that means I need to order planks of 2x16 timber suitable for outdoor use. I don’t think it exists in that spec so now what?
I’m thinking to make them out of plywood sheets. 2x25mm and 1 x 18mm all stuck together
I should be able to cut the pieces to size with a ts55 and guide rail. For each box 2 sides will be rip cut at an angle to give me 5 degrees. The other two sides will be rectangular but will have an angled mitred edge (excuse me if that’s not the correct terminology) that will match the angle of the other sides. This way I’ll create a flat plane for the windows to sit on.
Finally If you think sticking three sheets of ply together is acceptable, do I need to glue them or will screws be sufficient? Should I use nails?
I’m going to make the pieces where I live now then transport them by van to the house….it’s my own house by the way.
I welcome any and all advice that anyone has if you’ve been able to understand follow what I’m trying to achieve
Yasir
I need to build the upstands for 9 roof lights on a flat roof. 6 roof lights are 1200mm x 800mm and 3 roof lights are 1500mm x 1500mm.
I’m having problems with builders and I’m wondering if this is something I can do myself to expedite things…I’ll try my best to explain what it is I think I need to do then I’ll try to add some hand drawn sketches to better illustrate later today. Here is the requirements specification as I understand it
The total roof area is 8.5m x 8m approximately. The 8m length is the direction in which I need to achieve an inclination for rainwater(away from the house towards the garden)
The timber joists are in place and the apertures for the roof lights are ready
The roof is perfectly flat but I need a minimum 1 degree inclination. I have purchased firrings that are 8m in length and go from 200mm down to 0mm, this equates to around 1.3 degrees
The upstands need to rise 150mm above the flat roof
I think it’ll be easier to first build the upstands at 5 degrees and fix them directly to the roof joists rather than putting the firrings down first and subsequently fixing the roof lights into the firrings. This is because It’ll be more stable, I feel.
The problem with this approach is that it’ll be hard work to create the inclination: I’ll have to cut the firrings and fix them around the roof lights
Assuming I go down this route, the next problem is the construction technique for the upstand. The roof light diagram shows a cross section of 50mm thick timber on the inside with 18mm thick plywood on the outside. Plywood comes in sheets but timber comes in pre-cut sizes. I know I need 50mm (2 inch) but what height?
The firring is 20cm tall at it’s tallest point. On top of this will sit an OSB board (18mm), then either Fibreglass or roof felt (10mm?) That’s about 3cm in total so firring + roof covering = 23cm
If the upstand box needs to clear the roof by 150mm, then the tallest upstand needs to be 23cm + 15cm = 38 cm = approx 15 inches from the front…it then needs to be higher to the equivalent of 5 degrees at the back
I’m thinking I keep all the upstands exactly the same heights relative to each other so that from inside the house, when you look up they all look the same height. From the outside the upstands closer to the house will protrude around 150mm from the roof, those closest to the garden will extend more 38cm from the roof
I think that means I need to order planks of 2x16 timber suitable for outdoor use. I don’t think it exists in that spec so now what?
I’m thinking to make them out of plywood sheets. 2x25mm and 1 x 18mm all stuck together
I should be able to cut the pieces to size with a ts55 and guide rail. For each box 2 sides will be rip cut at an angle to give me 5 degrees. The other two sides will be rectangular but will have an angled mitred edge (excuse me if that’s not the correct terminology) that will match the angle of the other sides. This way I’ll create a flat plane for the windows to sit on.
Finally If you think sticking three sheets of ply together is acceptable, do I need to glue them or will screws be sufficient? Should I use nails?
I’m going to make the pieces where I live now then transport them by van to the house….it’s my own house by the way.
I welcome any and all advice that anyone has if you’ve been able to understand follow what I’m trying to achieve
Yasir
